Highlights

2019-4-01  New paper on the role of oxide ultrathin coatings on the performace of ZnO-based resistive switching in collaboration with K. Musselman at Univ. Waterloo
Ultrathin metal-oxide interface mediated ZnO nanowire memristive devices emulating synaptic behaviors. Adv. Electronic Mater.

One-dimensional semiconductor nanowires have been widely used as important building blocks in different device. However, the performance of semiconductor nanowire devices is strongly affected or hindered by the surface states/defects on the nanowires. Mitigation of effects of surface defects of nanowires is a great concern to realize reliable and predictable performance. In this paper, we demonstrate the introduction of an ultrathin metal oxide layer between Au electrodes and ZnO nanowire can minimize the surface effects of the ZnO nanowire, leading to reliable symmetrical threshold switching performance. Study of the conduction mechanism demonstrated that the TiOx interfacial layer functions as a barrier between the metal electrode and the nanowire, wherein the oxygen defects provide localized trap sites for electron hopping at low electric field as well as assisting the electron tunneling at high electric field. Several key synaptic functions including excitatory current response, facilitation
and depression, short-term plasticity are realized for the modified ZnO nanowire device, which are promising for neuromorphic computing applications. This bidirectional memristive device demonstrates that interface engineering between a metal electrode and a semiconductor nanowire can provide an important step in realizing reliable memristive devices, opening new approaches to assembling
neuromorphic systems with nanometer-sized features.





2019-2-15  We welcome Miguel Granados. He'll be doing an internship  in the group until the summer working on our SALD system.


2019-2-14  Easy patterning of MOF films on reactive surfaces thanks to microfluidics, a collabotarion with J. Puigmartí-Luis from ETH Zurich
In‐Flow MOF Lithography. Adv. Mater. Technologies. 

Continuous‐flow microfluidic systems are widely recognized as advanced and robust tools for materials synthesis. Indeed, the exquisite spatiotemporal control over reagent concentrations in a microfluidic channel has enabled the formation of composite materials and structures with unique features. Herein, we show for the first time that by combining reactive substrates with continuous‐flow microfluidic devices, material growth can be spatiotemporally driven and modulated on a surface. We demonstrate such unprecedented control by crystallizing and patterning compositional gradients of HKUST‐1 (a widely investigated metal‐organic framework (MOF)) on a reactive surface. We believe that this novel approach will engender new possibilities for incorporating MOFs on reactive surfaces, and thus for developing new advanced technological architectures and devices.
















2019-2-13  Our work selected as Frontispice in Adv. Func. Mater.



2019-2-06  Our work selected as Inside Cover in Adv. Mater. Interfaces



2019-2-04  Co-organiser of a symposium dedicated to ALD and CVD at the 2019 MRS Fall meeting. 


See the call for abstracts here

2019-1-10  Book Chapter on Spatial Atomic Layer Deposition
in, Chemical Vapor Deposition for Nanotechnology, Edited by Pietro Mandracci, IntechOpen

The chapter features a table with all materials synthesized (an published) via SALD at the time of publication (Sorry if I forgot any!). 


In conventional atomic layer deposition (ALD), precursors are exposed sequentially to a substrate through short pulses while kept physically separated by intermediate purge steps. Spatial ALD (SALD) is a variation of ALD in which precursors are continuously supplied in different locations and kept apart by an inert gas region or zone. Film growth is achieved by exposing the substrate to the locations containing the different precursors. Because the purge step is eliminated, the process becomes faster, being indeed compatible with fast-throughput techniques such as roll-to-roll (R2R), and much more versatile and easier and cheap to scale up. In addition, one of the main assets of SALD is that it can be performed at ambient pressure and even in the open air (i.e., without using any deposition chamber at all), while not compromising the deposition rate. In the present chapter, the fundamentals of SALD and its historical development are presented. Then, a succinct description of the different engineering approaches to SALD developed to date is provided. This is followed by the description of the particular fluid dynamics aspects and the engineering challenges associated with SALD. Finally, some of the applications in which the unique assets of SALD can be exploited are described.



















2018-12-19   Exploiting the CVD mode in close proximity AP SALD for making area selective deposition
Influence of the geometric parameters on the deposition mode in spatial atomic layer deposition: a novel approach to area-selective deposition
Coatings, 2018, 9(5), 5. Congratulations to César! 

Within the materials deposition techniques, Spatial Atomic Layer Deposition (SALD) is gaining momentum since it is a high throughput and low-cost alternative to conventional ALD. SALD relies on a physical separation (rather than temporal separation, as is the case in conventional ALD) of gas-diluted reactants over the surface of the substrate by a region containing an inert gas. Thus, fluid dynamics play a role in SALD since precursor intermixing must be avoided in order to have surface-limited reactions leading to ALD growth, as opposed to chemical vapor deposition growth (CVD). Fluid dynamics in SALD mainly depends on the geometry of the reactor and its components. To quantify and understand the parameters that may influence the deposition of films in SALD, the present contribution describes a Computational Fluid Dynamics simulation that was coupled, using Comsol Multiphysics®, with concentration diffusion and temperature-based surface chemical reactions to evaluate how different parameters influence precursor spatial separation. In particular, we have used the simulation of a close-proximity SALD reactor based on an injector manifold head. We show the effect of certain parameters in our system on the efficiency of the gas separation. Our results show that the injector head-substrate distance (also called deposition gap) needs to be carefully adjusted to prevent precursor intermixing and thus CVD growth. We also demonstrate that hindered flow due to a non-efficient evacuation of the flows through the head leads to precursor intermixing. Finally, we show that precursor intermixing can be used to perform area-selective deposition.















2018-11-30   Review on fast approaches to ALD
Speeding up the unique assets of atomic layer deposition   
Materials Today Chemistry, accepted.

Atomic Layer Deposition (ALD) has been traditionally regarded as an extremely powerful but slow thin-film deposition technique. The (perceived) limitation in terms of deposition rate has resulted in a slow penetration of the technology into mass manufacturing beyond established applications in the semiconductor industry until recently. At present, several developments have resulted in a significant increase in the use of ALD in a number of mass manufacturing applications. On the one hand, there is an increasing demand from the device makers side to incorporate nanotechnology in their products that relies on the unique advantages of ALD. On the other hand, a number of technical improvements have been implemented in the ALD method allowing it to be much faster. In this paper, we provide an overview of different High Throughput (HT) ALD approaches, putting them in perspective with other common HT deposition techniques already used in the industry. As an example, the use of HT ALD for Organic Light-Emitting Diodes (OLED) thin-film encapsulation is discussed.








 



2018-11-29   Cu2O thin films grow differently depending on the weather!
The role of humidity in tuning the texture and electrical properties of Cu2O thin films deposited via Aerosol Assisted CVD
Advanced Materials Interfaces, accepted. Congratulations to Hongjun! 

This work reports a study on the effect of carrier gas (CG) humidity on the texture and the resulting electronic properties of Cu2O thin films deposited using Aerosol Assisted Chemical Vapor Deposition (AA-CVD) at low temperatures (< 365 °C). By increasing the CG humidity, the preferred orientation of the films can be tuned from [110] to [111]. By studying the initial stages of film deposition, a different growth mode is found for dry and humid conditions, which in turn directs the final texture of the films. The analysis of the electric properties of the thin films by Hall-effect shows that while carrier concentration remains in the order of 1015 cm-3 when using both in dry and humid conditions, Cu2O samples deposited with humid CG generally present a higher mobility, up to 17 cm2 V-1s-1. [111] Textured Cu2O films with high mobility were used to fabricate a diode by depositing a ZnO layer on top using Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD). The diode shows an excellent rectifying behavior with a high asymmetry close to 104 between -1 V and +1 V.  















2018-11-28   MIM diodes made fast and in the open air! in collaboration with K. Musselman from Univ. Waterloo
Quantum-tunneling metal-insulator-metal diodes made by rapid atmospheric pressure chemical vapor deposition
Advanced Functional Materials, accepted. Congratulations to Viet! 

A quantum-tunneling metal-insulator-metal (MIM) diode is fabricated by atmospheric pressure chemical vapor deposition (AP-CVD) for the first time. This scalable method is used to produce MIM diodes with high-quality, pinhole-free Al2O3 films more rapidly than by conventional vacuum-based approaches. This work demonstrates that clean room fabrication is not a prerequisite for quantum-enabled devices. In fact, the MIM diodes fabricated by AP-CVD show a lower effective barrier height (2.20 eV) at the electrode-insulator interface than those fabricated by conventional plasma-enhanced atomic layer deposition (2.80 eV), resulting in a lower turn on voltage of 1.4 V, lower zero-bias resistance and better asymmetry of 107. 










2018-11-28  using UV radiation under soft conditions to improve the mobility of air-processed ZnO:Al thin films
Increasing the Electron Mobility of ZnO-Based Transparent Conductive Films Deposited by Open-Air Methods for Enhanced Sensing Performance
ACS Applied Nano Materials, accepted. Congratulations to Viet!!

The development of open-air, high-throughput, low-cost thin film fabrication techniques has immense potential and interest in optoelectronics. However, the oxygen-rich atmosphere associated with such processes can have detrimental effects on the electrical properties of the deposited films. An example of this is found in materials based on ZnO, for which atmospheric processing results in low mobility values. This stems mainly from adsorbed oxygen species at the grain boundaries, which limit carrier transport. This paper describes the effect of a low-temperature UV treatment on the electrical properties of ZnO and aluminum doped zinc oxide (ZnO:Al) films deposited by Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD). Thanks to the mild UV treatment, a significant decrease in the amount of oxygen traps at the grain boundaries has been observed. This results in a large improvement of the carrier mobility, up to 47 times for undoped ZnO and 16 times for ZnO:Al. The effect of temperature (RT to 220 °C) during the UV treatment on the conductivity of undoped ZnO and ZnO:Al films is discussed. The study of the time-dependent conductivity of ZnO and ZnO:Al films using tunneling emission based models provides a simple means for extracting the grain boundary trap density, a critical parameter in semiconductors that is usually not easy to estimate. We show that the high conductivity of the UV-treated films can be preserved when exposed to oxygen at high temperature thanks to a very thin alumina (Al2O3) barrier layer. Finally, we demonstrate that the effect of UV illumination of thin ZnO films deposited in oxidizing atmospheres can be used to design improved UV or oxygen sensors.














2018-10-08  Congratulations to Viet Nguyen for passing his PhD viva!!! Excellent thesis and excellent Viva!!!



2018-10-01 We welcome Chiara Crivello and Abderrahime Sekkat, new PhD students in the SALD group.





2018-09-20   Very happy about the many positive feedback on our ALD symposium at the E-MRS

Congratulations to Eun Gyo Jeong for the best poster award, sponsored by Wiley Advanced Materials Interfaces (Thanks Dr. A. Troeger, Wiley Editor, for giving the award to Prof. Riedl in representation of Eun Gyo Jeong).

Congratulations to Sandra Haschke for the best graduate student presentation, sponsored by Picosun (Thanks to C. Hossbach for giving the award)


Below a picture of the nice dinner between most of the invited speakers, the scientific and the organising committee. Thanks to Prof. Marek Godlewski for taking us to such a nice place!



2018-09-11   Nice Surprise! Viet's image has been chosen for the cover of the June issue of Nanotoday
Congratulations to Viet! 




2018-08-16   CuO spotted within Cu2O thin films. In collaboration with E. Fortunato from CENIMAT. 
Visualization of nanocrystalline CuO in the grain boundaries of Cu2O thin films and effect on band bending and film resistivity
APL Materials, 2018Congratulations to Hongjun!!

Direct evidence for the presence of a CuO structure in the grain boundaries of Cu2O thin films is provided by high resolution automated phase and orientation mapping (ASTAR), which was not detectable by classical transmission electron microscopy techniques. Conductive atomic force microscopy (C-AFM) revealed that the CuO causes a local loss of current recti.cation at the Schottky barrier between the C-AFM tip and Cu2O. The suppression of CuO formation at the Cu2O grain boundaries is identifi.ed as the key strategy for future device optimization.











2018-08-8   Photodectors with fast response deposited processed at low temperature and atmospheric pressure. 
ZnO / CuCrO2 Core-Shell Nanowire Heterostructures for Self-Powered UV Photodetectors with Fast Response
Advanced Functional Materials, 28, 1803142, 2018Congratulations to Thomas and Joao!!

 

An original self-powered UV photodetector integrating ZnO / CuCrO2 core-shell nanowire heterostructures is fabricated using low-cost and scalable chemical deposition techniques operating at moderate temperatures. A 35 nm-thick delafossite phase CuCrO2 shell is formed with high uniformity by aerosol-assisted chemical vapor deposition over an array of vertically aligned ZnO nanowires grown by chemical bath deposition. The CuCrO2 shell consists of columnar grains at the top of ZnO nanowires as well as nano-grains with some preferential orientations on their vertical sidewalls. The ZnO / CuCrO2 core-shell nanowire heterostructures exhibit significant diode behavior, with a rectification ratio approaching 1.2 x 104 at ±1 V, as well as a high optical absorptance above 85% in the UV part of the electromagnetic spectrum. A high UV responsivity at zero bias under low-power illumination of up to 3.43 mA/W under a 365 nm UV lamp, and up to 5.87 mA/W at 395 nm from spectrally-resolved measurements, alongside a high selectivity with a UV-to-visible (395-550 nm) rejection ratio of 106 are measured. The short rise and decay times of 32 and 35 µs, respectively, both measured at zero bias, further establish these devices as promising candidates for cost-efficient, all-oxide self-powered UV photodetectors.



2018-07-31   Invited talk at the AVS ALD conference. 
you can see my presentation at the following site (AVS membership required): https://www.pathlms.com/avstechnicallibrary/events/1220/video_presentations/113727


2018-06-16   Rationalisation of nanocomposite hazy transparent conductive oxides
Hazy Al2O3-FTO Nanocomposites: A Comparative Study with FTO-Based Nanocomposites Integrating ZnO and S:TiO2 Nanostructures
Nanomaterials, 2018. Congratulations Shan-Ting!!

We report the use of Al2O3 nanoparticles in combination with fluorine doped tin oxide (F:SnO2, aka FTO) thin films to form hazy Al2O3-FTO nanocomposites. In comparison to previously reported FTO-based nanocomposites integrating ZnO and sulfur doped TiO2 (S:TiO2) nanoparticles (i.e., ZnO-FTO and S:TiO2-FTO nanocomposites), the newly developed Al2O3-FTO nanocomposites show medium haze factor HT of about 30%, while they exhibit the least loss in total transmittance Ttot. In addition, Al2O3-FTO nanocomposites present a low fraction of large-sized nanoparticle agglomerates with equivalent radius req > 1 μm; effectively 90% of the nanoparticle agglomerates show req < 750 nm. The smaller feature size in Al2O3-FTO nanocomposites, as compared to ZnO-FTO and S:TiO2-FTO nanocomposites, makes them more suitable for applications that are sensitive to roughness and large-sized features. With the help of a simple optical model developed in this work, we have simulated the optical scattering by a single nanoparticle agglomerate characterized by bottom radius r0, top radius r1, and height h. It is found that r0 is the main factor affecting the HT(λ), which indicates that the haze factor of Al2O3-FTO and related FTO nanocomposites is mainly determined by the total surface coverage of all the nanoparticle agglomerates present.












2018-05-31   Guest Editor of the Frontiers Research Topic: Window Electrodes for Emerging Thin Film Photovoltaics


2018-05-23  Deadline approaching! 28th May: Symposium dedicated to ALD in the coming E-MRS meeting in Warsaw



2018-05-17  A new model for highly doped semiconducting polycrystalline thin films. 
Electron tunneling through grain boundaries in transparent conductive oxides and implications for electrical conductivity
Materials Horizons, accepted.  Congratullations Viet!

In this work, we have applied the Airy Function Transfer-Matrix Method to provide a numerical description of the charge scattering mechanisms taking place at the grain boundaries in polycrystalline, degenerately Al-doped ZnO (ZnO:Al) films, one of the most studied Transparent Conductive Oxides (TCOs). By discretizing the potential barrier at the grain boundary into linear segments, an accurate calculation of the electron tunneling probability through the grain boundaries have been obtained. Conversely to analytical models based on the Wentzel–Kramers–Brillouin (WKB) approximation, our new approach is valid for any doping level. We thus provide a complete model that allows a comprehensive explanation for carrier transport in highly doped semiconductors, for which charge tunneling across grain boundaries cannot be neglected. We have tested our model with ZnO:Al thin films prepared by different physical and chemical deposition techniques, namely, sputtering, atomic layer deposition and atmospheric pressure spatial atomic layer deposition. A linear relationship between trap density at the grain boundaries and carrier density has been extracted by fitting our model to Hall mobility data for the different samples. Our results provide a guidance on how to adapt the deposition conditions to obtain high-quality materials, with an optimum ratio between optical and electrical properties as required for specific applications.










2018-05-10  Making  AgNWs transparent electrodes more stable with oxide coatings deposited by AP-SALD. 
Stability enhancement of silver nanowire networks with conformal ZnO coatings deposited by atmospheric pressure spatial atomic layer deposition
ACS Advanced Materials & Intercaces. Congratullations Viet!

Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerged as one of the most attractive alternatives to transparent conductive oxides to be used in flexible optoelectronic applications. However, AgNW networks still suffer from chemical, thermal and electrical instabilities which in some cases can hinder their efficient integration as transparent electrodes in devices such as solar cells, transparent heaters, touch screens or organic light emitting diodes (OLEDs). We have used atmospheric pressure spatial atomic layer deposition (AP-SALD) to fabricate hybrid transparent electrode materials in which the AgNW network is protected by a conformal thin zinc oxide layer. The choice of AP-SALD allows to maintain the low-cost and scalable processing of AgNW based transparent electrodes. The effects of the ZnO coating thickness on the physical properties of AgNW networks are presented. The composite electrodes show a drastic enhancement of both thermal and electrical stabilities. We found that bare AgNWs were stable only up to 300 °C when subjected to thermal ramps while the ZnO coating improved stability up to 500 °C. Similarly, ZnO coated AgNWs exhibited an increase of a 100 % in electrical stability with respect to bare networks, withstanding up to 18 V. A simple physical model shows that the origin of the stability improvement is the result of hindered silver atomic diffusion thanks to the presence of the thin oxide layer and the quality of the interfaces of hybrid electrodes. The effects of ZnO coating on both the network adhesion and optical transparency are also discussed. Finally, we show that the AP-SALD ZnO-coated AgNW networks can be effectively used as very stable transparent heaters.






2018-05-03  Seeing how good silver nanowire networks are, and how they fail.
Electrical Mapping of Silver Nanowire Networks: A Versatile Tool for Imaging Network Homogeneity and Degradation Dynamics during Failure
ACS NanoCongratullations Thomas! 

Electrical stability and homogeneity of silver nanowire (AgNW) networks are critical assets for increasing their robustness and reliability when integrated as transparent electrodes in devices. Our ability to distinguish defects, inhomogeneities, or inactive areas at the scale of the entire network is therefore a critical issue. We propose one-probe electrical mapping (1P-mapping) as a specific simple tool to study the electrical distribution in these discrete structures. 1P-mapping has allowed us to show that the tortuosity of the voltage equipotential lines of AgNW networks under bias decreases with increasing network density, leading to a better electrical homogeneity. The impact of the network fabrication technique on the electrical homogeneity of the resulting electrode has also been investigated. Then, by combining 1P-mapping with electrical resistance measurements and IR thermography, we propose a comprehensive analysis of the evolution of the electrical distribution in AgNW networks when subjected to increasing voltage stresses. We show that AgNW networks experience three distinctive stages: optimization, degradation, and breakdown. We also demonstrate that the failure dynamics of AgNW networks at high voltages occurs through a highly correlated and spatially localized mechanism. In particular the in situ formation of cracks could be clearly visualized. It consists of two steps: creation of a crack followed by propagation nearly parallel to the equipotential lines. Finally, we show that current can dynamically redistribute during failure, by following partially damaged secondary pathways through the crack.







2018-05-2 Seminar in METU, Ankara, for a crowded auditorium! Thanks a lot to Dr. Emrah Unlanan for organising it. Superb research and fantastic team!



2018-04-6 With Viet and Thomas at the MRS spring meeting, in Phoenix.




2018-04-1 We welcome Lukas Fusek. He'll be doing an internship  in the group until the summer working on our SALD system.




2018-03-18  Congratulations to Viet Nguyen, winner of the Nanoart Contest (February 2018), awarded by the Nanosciences Fondation.



2018-03  Organization of a symposium dedicated to ALD in the coming E-MRS meeting in Warsaw




2017-12-23 Trasparent electrodes based on Cu Nanowire Networks become more stable thanks to plastic and SALD encapsultaion. In collaboration with J-P. Simonato from LETI
Oxidation of Copper Nanowires based Transparent Electrodes in Ambient Conditions and their Stabilization by Encapsulation. Application to Transparent Film Heaters

Whereas the integration of silver nanowires in functional devices has reached a fair level of
maturity, the integration of copper nanowires still remains difficult, mainly due to the intrinsic
instability of copper nanowires in ambient conditions. In this paper, copper nanowire based
transparent electrodes with good performances (33 Ω sq−1 associated with 88% transparency)
were obtained, and their degradation in different conditions was monitored, in particular by
electrical measurements, transmission electron microscopy, x-ray photoelectron spectrometry
and Auger electron spectroscopy. Several routes to stabilize the random networks of copper
nanowires were evaluated. Encapsulation through laminated barrier film with optical clear
adhesive and atmospheric pressure spatial atomic layer deposition were found to be efficient and
were used for the fabrication of transparent film heaters.






2017-12-13 Farewell lunch with Hongjun. Good luck for the future!!

This is one of the best things when doing research: 8 people, 8 nationalities!!! From left to right: César (México), Hongjun (China), Me (Spain), Viet (Vietnam), Thomas (Fance), Getnet (Ethiopia), Sara (Iran), Evgenii (Russia). And even the one missing (my fault), Dorina (Greece).





















2017-12-05 Building bridges thanks to ALD and new materials. 



2017-11-27 We welcome Pedro Veiga. He'll be doing an internship  in the group until the summer working on our SALD system. 



2017-11-06  Invited lecturer and speaker at the 2017 edition of the  INT MINATEC SCHOOL and IWNA conference, Vietnam.







2017-10-31  Congratulations to Hongjun Liu for passing his PhD viva!!! Great job!!!



At the LMGP stand in the French Science Week 2017



We welcome DorinaPapanastasiou, new PhD student in the group, who'll be working on Silver nanowire networks. 



Invited paper in CRAS just published
Spatial Atomic Layer Deposition (SALD), an emerging tool for energy materials. Application to new-generation photovoltaic devices and transparent conductive materials

Materials properties are the keystone of functional devices for energy including energy conversion, harvesting or storage. But to market new energy materials, the development of suitable processing methods allowing affordable prices is needed. Recently, a new approach to atomic layer deposition (ALD) has gained much momentum. This alternative approach is based on separating the precursors in space rather than in time, and has therefore been called Spatial ALD (SALD). With SALD, the purge steps typical of ALD are not needed and thus deposition rates a hundred times faster are achievable. Additionally, SALD can be easily performed at ambient atmosphere, thus it is easier and cheaper to scale up than conventional ALD. This opens the door to widespread industrial application of ALD for the deposition of energy materials for applications including solar energy, energy storage, or smart windows. SALD is presented here and examples of application to photovoltaics and transparent conductive materials are given. We show that SALD is capable of producing high-quality films fully suited for device integration.


















Probing the nature of TiO2 blocing layers for photovolatic applications
Polymorphism of the Blocking TiO2 Layer Deposited on F:SnO2 (FTO) and Its Influence on the Interfacial Energetic Alignment
Journal of Physical Chemistry C, accepted. Congratulations to Shan-Ting Zhan!!


As widely employed in dye-sensitized, perovskite, and quantum-dot solar cells, the interface between F-doped SnO2 (FTO) and blocking TiO2 (b-TiO2) is essential in understanding the working principles of these types of solar cells. In this work, we have deposited b-TiO2 layers using a simple sol-gel method. While the b-TiO2 layers deposited on Si (100) wafers form pure anatase polymorph, we have found that the rutile structure of the FTO substrates consistently induces the b-TiO2 layers to crystallize into mixed anatase and rutile polymorphs - the same is observed on rutile RuO2 substrates. This indicates that the rutile structural similarity favors the formation of rutile polymorph in b-TiO2 layers; due to the coexistence of both anatase and rutile polymorphs, the interface of FTO/b-TiO2 is essentially inhomogeneous. We also show that the amount of rutile polymorph present in the b-TiO2 layer is a function of layer thickness, with rutile polymorph dominating in thin b-TiO2 layers. As a result, the energetic alignment at the FTO/b-TiO2interface in general still favors the charge transport. This is confirmed by directly probing an ultra-thin (<10 nm) b-TiO2 layer using X-ray photoelectron spectroscopy (XPS). We emphasize that the rutile structure of FTO substrate plays a significant role in determining the polymorph of successively deposited b-TiO2 layer, which in turn affects the energetic alignment with FTO electrodes and mesoporous nanocrystalline TiO2, and ultimately the performance of solar devices.










New paper on the deposition of FTO epitaxial films using low-cost spray pyrolysis 
High quality epitaxial fluorine-doped SnO2 films by ultrasonic spray pyrolysis: in-depth structural and physical property investigation
Materials and Design, 2017, 132, 518-525. Congratulations to Shan-Ting Zhan!!




Despite its wide use in the display and photovoltaic industries, fluorine-doped tin oxide (F:SnO2, FTO) has been studied only in its polycrystalline form. In this work, we report on the first growth of epitaxial FTO thin film by ultrasonic spray pyrolysis – a simple chemical deposition method – and we reveal the structure-property interplay by investigating in details its growth, morphology and strain/defects. Epitaxial FTO films are successfully grown on (110) rutile TiO2 single crystals and form mosaic domains with an out-of-plane distribution smaller than 0.5°, showing high structural quality comparable to epitaxial films prepared by molecular beam epitaxy and pulsed-laser deposition. Owing to the large lattice mismatch with rutile TiO2, the FTO film develops significant structural defects to release the epitaxial strain and is consequently nearly fully relaxed with a slight residual strain of 0.1-0.2%. With the help of an innovative nano-beam precession electron diffraction technique, the strain distribution is mapped at the TiO2/FTO interface, from which we could identify the interfacial and secondary strain relaxation taking place mainly in the first 22 nm in the FTO film. The Hall-mobility of the epitaxial FTO films is close to the state-of-the-art and expected to improve further at lower carrier concentrations.














New paper on the deposition of Ag coating by Aerosol Assisted MOCVD using two new Ag metalorganic precursors
http://pubs.rsc.org/en/content/articlelanding/2014/dt/c7dt01647f#!divAbstract Congratulations to Hongjun Liu!!


This work reports two new silver metalorganic precursors for the chemical vapor deposition of Ag metallic coatings. Both precursors are based on β-diketonate adducts, namely, Ag(hfac)(L) (H-hfac= 1,1,1,5,5,5-hexafluoro-2,4-pentanedione), where L is 1,10-phenanthroline (phen) or 2,5,8,11-tetraoxadodecane (triglyme). Using these ligands, the designed precursors have better solubility in alcoholic solvents and are less toxic and costly than previously reported ones. The new precursors have been characterized and their crystallographic structure solved. With the new triglyme precursor, [Ag(triglyme)2]+[Ag(hfac)2]- , pure metallic Ag coatings made of Ag nanoparticles about 20 nm in diameter were succesfully deposited on glass and Si substrates using Aerosol Assisted Metalorganic CVD (AA-CVD).











A very nice initiative, worth supporting



We welcome Kissan Mistry, PhD student in the University of Waterloo, Canada, who'll be visiting  during three months to work on the deposition of ZnO based devices using our SALD system within the framework of our ongoing collaboration with Prof. Musselman's group.




We welcome Théodulf Rousseau, who has joined the group as Postdoc (funded by CEMAM) for the development of solar cells with innovative architectures




New paper on AgNWs based transparent conductive materials
Transparent electrodes based on silver nanowire networks: from physical considerations towards device integration
Materials 201710(6), 570; doi:10.3390/ma10060570

The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells, flexible light-emitting devices, touch screens, electromagnetic devices, and flexible transparent thin film heaters. Currently, the most commonly used TCM for such applications (ITO: Indium Tin oxide) suffers from two major drawbacks: brittleness and indium scarcity. Among emerging transparent electrodes, silver nanowire (AgNW) networks appear to be a promising substitute to ITO since such electrically percolating networks exhibit excellent properties with sheet resistance lower than 10 Ω/sq and optical transparency of 90%, fulfilling the requirements of most applications. In addition, AgNW networks also exhibit very good mechanical flexibility. The fabrication of these electrodes involves low-temperature processing steps and scalable methods, thus making them appropriate for future use as low-cost transparent electrodes in flexible electronic devices. This contribution aims to briefly present the main properties of AgNW based transparent electrodes as well as some considerations relating to their efficient integration in devices. The influence of network density, nanowire sizes, and post treatments on the properties of AgNW networks will also be evaluated. In addition to a general overview of AgNW networks, we focus on two important aspects: (i) network instabilities as well as an efficient Atomic Layer Deposition (ALD) coating which clearly enhances AgNW network stability and (ii) modelling to better understand the physical properties of these networks. 
View Full-Text





Congratulations to Shan-ting Zhang for passing her PhD viva!!! Excellent job!!!






New paper on ZnO based thin films deposited by SALD as components in solar cells
Deposition of ZnO based thin films by Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD) for application in solar cells 


The use of Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD) has gained popularity in the last decade. The success of this technique relies on the possibility to deposit thin films in a fast, vacuum-free, low-cost, low-damage and high throughput way. In this work, we present ZnO and Aluminium doped ZnO (AZO) films deposited by AP-SALD at low temperature (<220 ºC) with high uniformity and conformity. The ZnO films present a high transparency of 80 % – 90 % in the visible range, with a tuneable band-gap, between 3.30 eV and 3.55 eV, controlled by the deposition temperature. Carrier density reaches values greater than 3 x 1019 cm-3, while the electron mobility of the films is as high as 5,5 cm2V-1s-1, resulting in an optimum resistivity of 5x 10-2 Ohm.cm. By doping ZnO with aluminium, the resistivity decreases down to 5,57 x 10-3 Ohm.cm, as a result of a significant increase in carrier density up to 4,25x 1020 cm-3. The combination of ZnO thin films with p-type cuprous oxide (Cu2O), deposited by Aerosol Assisted Metal Organic Chemical Vapor deposition (AA-MOCVD) allowed the formation of oxide-based pn junctions. The dark I-V characteristic curve confirms a rectifying behaviour, opening the window for the production of all-oxide solar cells completely by chemical vapour deposition methods. We also show the potential of AP-SALD to deposit AZO as transparent conductive oxide (TCO) layer for silicon heterojunction solar cells.






Highlighted in Twitter by Bald Engineering while presenting in the ALD4INDUSTRY workshop 2017, Dresde, Germany



Beautiful TiO2 microflowers with hierarchical structure. 
Structural study of TiO2 hierarchical microflowers grown by aerosol assisted MOCVD.
CrystEngComm, 2017, 19, 1535-1544. Congratulations to Sayari Biswas!!



TiO2 is a promising n-type semiconductor for optoelectronic devices, in particular dye sensitized and hybrid solar cells, and
more recently for hybrid perovskite-based solar cells,as well as for lithium batteries. For these applications, TiO2 structures
offering a high mesoporosity and surface area are especially interesting as it increases the efficiency of phenomena taking
place at the interfaces. We have used aerosol assisted metalorganic chemical vapor deposition (AA-MOCVD) to deposit
TiO2 films containing hierharchical TiO2 microflowers. Both the film and the microflowers crystallize with the anatase
strucrture. The microflowers have diameters of around 2-3 microns while the petals are only several nanometers thick.
The density of microflowers and of petals in each flower can be controlled by adjusting the deposition parameters. These
microstructures are stable to high temperature annealing (950 °C). In this communication, we describe the synthesis of the
microflowers and present the detailed study of their structural and morphological properties.











Close proximity AP-SALD: Fast deposition of functional films on 3D devices shown
Rapid open-air deposition of uniform, nanoscale, functional coatings on nanorod arrays
RSC Nanoscale horizons, 2017, 2, 110-117.

Coating of high-aspect-ratio nanostructures has previously been achieved using batch processes poorly suited for high-throughput manufacturing. It is demonstrated that uniform, nanoscale coatings can be rapidly deposited on zinc oxide nanorod arrays in open-air using an atmospheric pressure spatial deposition system. The morphology of the metal oxide coatings is examined and good electrical contact with the underlying nanorods is observed. The functionality of the coatings is demonstrated in colloidal quantum dot and hybrid solar cells.



















HDR (habilitation à diriger des recherches) obtained!




New member of the Ag-Cu mixed oxides family: (in collaboration with N. Casañ-Pastor from ICMAB-CSIC)
Ag2Cu3Cr2O8(OH)4:A new bidimensional silver-copper mixed -oxyhydroxide with in-plane ferromagnetic coupling
Dalton Transactions, 2017,46, 1093-1104.

Ag2Cu3Cr2O8(OH)4, a new Ag-Cu-Cr-O layered mixed oxide, prepared by soft hydrothermal heterogeneous reactions, is reported. The new phase is an oxohydroxide and presents a structure with alternating brucite-like Cu-O and Ag-O layers and connected by individual chromate groups. The crystallographic structure has been solved and refined from high resolution powder X-ray diffraction data and is supported by density functional theory calculations, yielding a triclinic, space group P-1, a = 5.3329(1) Å, b = 5.3871(1) Å, c = 10.0735(1) Å, α = 80.476(1) °, β = 87.020(1) °, γ = 62.383(1)°. Bond valence sums suggest the formulation Ag+2Cu2+3Cr6+2O8(OH)4, an electronic state fully supported by X-ray photoelectron spectroscopy (XPS) and Cr K-edge X-ray absorption near edge structure (XANES) measurements.  Ag2Cu3Cr2O8(OH)4 exhibits bidimensional Cu-O-Cu ferromagnetic correlations that are apparent at much higher temperatures than in other similar Cu-O layered structures, without coupling between Cu-O layers, which represents a unique case in the recent family of silver copper oxides. The role of Ag inducing bidimensionality in copper oxides is therefore expanded further with the presence of chromate anions. Ab initio calculations using density functional theory show that the electronic states involved originate mainly from Cu and OH orbitals, with minor contributions from Cr and the O atoms linking the Cr tetrahedra to the brucitic Cu-O layer, and almost no contribution from Ag. Further modeling of the in-plane magnetic interactions between Cu atoms suggests that coupled magnetized stripes are responsible for the observed behavior. The results are discussed in relation with previous Ag-Cu mixed oxide phases where metallic behavior or ferro-antiferro transitions had been observed. The structure of this new Ag-Cu-O phase as compared with previous silver copper oxides supports the conclusion that Ag-Cu layered ordering is favored in oxidizing conditions.

 












Congratulations to César Masse, selected for the eit Innoenergy doctorate program!!!


New paper: Enhancing the stability of  transparent heaters  based  on silver nanowire networks with ALD TiO2 coatings.
Understanding the mechanisms leading to failure in metallic nanowire-based transparent heaters, and solution for stability enhancement
Nanotechnology, 2017, 28, 055709Congratulations to Mélanie Lagrange!!


Silver nanowire (AgNW) networks are emerging as one of the most promising alternative to indium tin oxide (ITO) for transparent electrodes in flexible electronic devices. They can be used in several optoelectronic applications such as solar cells, touch panels and organic light emitting diodes. Recently they have also proven to be very efficient when used as transparent heaters (TH). In addition to the study of AgNW networks as TH in regular use, i.e. at low voltage and moderate temperature, their stability and physical behavior at higher voltages and for longer durations should be studied in view of integration into real devices. The properties of AgNW networks deposited by spray coating on glass or flexible transparent substrates are thoroughly studied via in situ measurements. The AgNW networks’ behavior at different voltages for different durations and under different atmospheric conditions, both in air and under vacuum, has been examined. At low voltage, a reversible electrical response is observed while irreversibility and even failure are observed at higher voltages. In order to gain a deeper insight into the behavior of AgNW networks used as transparent heaters, simple but realistic physical models are proposed and found to be in fair agreement with experimental data. Finally, as the stability of AgNW networks is a key issue, we demonstrate that coating AgNW networks with a very thin layer of TiO2 using atomic layer deposition improves the material resistance against electrical and thermal instabilities without altering optical transmittance. We show that the critical annealing temperature associated to network breakdown increases from 270 °C for as deposited AgNW networks to 420 °C for AgNW networks coated with TiO2. Similarly, the electrical failure which occurs at 7 V for as deposited networks has been increased to 13 V for TiO2 coated networks. TiO2 also proved to stabilize AgNW networks during long duration operation and at high voltage. Temperature higher than 235 °C was achieved at 7 V without failure.


New paper on highly conductive TiO2-FTO composite transparent electrodes with tunable properties:
Tuning the properties of F:SnO2 (FTO) nanocomposites with S:TiO2 nanoparticles as promising hazy transparent electrodes for photovoltaics applications.
J. Mater. Chem. C, 2017,5, 91-102. Congratulations to Shan-Ting Zhan!!


The proper choice of nanoparticles is proved to be essential in tuning the properties of F:SnO2 (FTO) nanocomposites. With the use of more conductive sulphur-doped TiO2 (S:TiO2) nanoparticles, the sheet resistance of S:TiO2-FTO nanocomposites is successfully reduced down to 38% as compared to standard flat FTO (11.7 Ω/sq), while the haze factor of the S:TiO2-FTO nanocomposites can be varied from almost zero (reference flat FTO) up to 60%; in the meantime the majority of <110> oriented S:TiO2 nanoparticles leads to a strong (110) texture of resulting S:TiO2-FTO nanocomposites by local epitaxy. Careful morphology analyses and angle-resolved measurements reveal that the haze factor is proportional to the total surface coverage of the S:TiO2 nanoparticle agglomerates while the feature size of the agglomerates determines the angular distribution of the scattered light – this is confirmed by an angle-resolved Mueller matrix polarimeter which allows to obtain the optical microscopic and angle-resolved images of the exact same textured region. Our work establishes the guidelines to fabricate FTO and other transparent conductive oxide (TCO) nanocomposites as promising electrodes in solar cells with tunable structural, electrical, and optical properties. 





Project SOLAR-NOVOCELL selected by Linksium  for going on maturation stage. 
This project is part of my Marie Curie CIG CHEMABEL grant and aims to develop alternative, more efficient and cheaper solar cell nanoarchitectures. 



Seminar on SALD. Waterloo Institute for Nanotechnology (WIN) 



New paper on the deposition of epitaxial fluoride films by MOCVD: (in collaboration with G. Malandrino, from Univ. Catania)
The quest towards epitaxial BaMgF4 thin films:  exploring MOCVD as a chemical scalable approach for the deposition of complex metal fluoride films. 
Dalton Transactions, 2016,45, 17833-17842Congratualations to Sergio Battiato!



Conventional and Pulsed Liquid Injection MOCVD processes  (C-MOCVD and PLI-MOCVD) have been explored as synthetic routes for the growth of BaMgF4 on Si (100) and single crystalline SrTiO3 (100) substrates. For the two applied approaches, the volatile, thermally stable
b-diketonate complexes Ba(hfa)2tetraglyme and Mg(hfa)2(diglyme)2(H2O)2 have been used as single precursors (C-MOCVD) or as a solution multimetal source (PLI-MOCVD). Structural characterization through X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) analyses confirmed the formation of epitaxial BaMgF4 films on SrTiO3 substrates. Energy dispersive X-ray (EDX) analyses  have been used to confirm composition and purity of deposited films. The impact of process parameters on film properties has been addressed, highlighting the strong influence of precursor ratio, deposition temperature and oxygen partial pressure on composition, microstructure and morphology of the films. Both methods appear well suited for the growth of the BaMgF4 phase, but while  PLI-MOCVD yields a more straightforward control of the precursor composition that reflects on film stoichiometry, C-MOCVD provides an easier control of the degree of  texturing as a function of temperature.










New paper showing the application of IR thermography for the live imaging of the formation of electronic percolation pathways in Ag nanowire networks:
Nano Letters, accepted 2016.  Congratulations to Thomas Sannicolo!


Advancement in the science and technology of random metallic n
anowire (MNW) networks is crucial for their appropriate integration in many applications, including transparent electrodes for optoelectronics and transparent film heaters. We have recently highlighted the discontinuous activation of efficient percolating pathways (EPPs) for networks having densities slightly above the percolation threshold. Such networks exhibit abrupt drops of electrical resistance when thermal or electrical annealing is performed, giving rise to a “geometrically quantized percolation”. In this letter, Lock-in Thermography (LiT) is used to provide visual evidence of geometrical quantized percolation: when low voltage is applied to the network, individual “illuminated pathways” can be detected and new branches get highlighted as the voltage is incrementally increased. This experimental approach has allowed us to validate our original model and map the electrical and thermal distributions in silver nanowire (AgNW) networks. We also study the effects of electrode morphology and wire dimensions on quantized percolation. Furthermore we demonstrate that the network failure at high temperature can also be governed by a quantized increase of the electrical resistance, corresponding to the discontinuous destruction of individual pathways (anti-percolation). More generally, we demonstrate that LiT is as a promising tool for the detection of conductive sub-clusters, as well as hot spots in AgNW networks.  









NEW SALD system developed and Book on Materials For Energy are featured in MINANEWS




We welcome Cesar Masse de la Huerta, who will join us soon as a PhD student, funded by CONACYT, to work on the development of SALD for the fabrication of innovative solar cells. 

Photo:

Congratulations to Viet Nguyen for the "Best Poster Award" in the RAMSES School, Milan, Italy. 

nguyen viet-200.jpg

We welcome Salvatore Sanzaro, from the University of Catania, who will join the group during 3 months to grow TiO2 nanostructures and TCOs by CVD and Spray Pyrolysis for application in solar cells.

Salvatore Sanzaro

We welcome Stéphane Brochen, who has joined the group as Postdoc (funded by CEMAM) for the development of solar cells with innovative architectures

Brochen-S-200.jpg

New book coedited with Prof. Moya on Materials for Energy
http://www.panstanford.com/books/9789814411813.html


Member of the organizing committee of RAFALD2016


Congratulations to Sayari Biswas for the 3rd prize to the best 2015 Nanoart image contest.



Congratulations to Viet Nguyen who has rated 1 out of 82 in his Materials Science and Engineering undergrad program. INSA Lyon


New paper on the application of AP-SALD to the fundamental study of new generation PV devices:
The Influence of an Inorganic Interlayer on Exciton Separation in Hybrid Solar Cells.
ACS Nano, accepted 2015.  Congratulations to Claire Armstrong!




"It has been shown that in hybrid polymer-inorganic photovoltaic devices, not all the photo-generated excitons dissociate at the interface immediately, but can instead exist temporarily as bound charge pairs (BCPs). Many of these BCPs do not contribute to the photocurrent as their long lifetime as a bound species promotes various charge carrier recombination channels. Fast and efficient dissociation of BCPs is therefore considered a key challenge in improving the performance of polymer-inorganic cells. Here we investigate the influence of an inorganic energy cascading Nb2O5 interlayer on the charge carrier recombination channels in poly(3-hexylthiophene-2,5-diyl) (P3HT)-TiO2 and PbSe colloidal quantum dot-TiO2 photovoltaic devices. We demonstrate that the additional Nb2O5 film leads to a suppression of BCP-formation at the heterojunction of the P3HT cells and also a reduction in the non-geminate recombination mechanisms in both types of cells. Furthermore we provide evidence that the reduction in non-geminate recombination in the P3HT-TiO2 devices is due in part to the passivation of deep mid-gap trap states in the TiO2, which prevents trap assisted Shockley-Read-Hall recombination. Consequently a significant increase in both the open-circuit voltage and the short-circuit current was achieved, in particular for P3HT-based solar cells where the power conversion efficiency increased by 39%."







Congratulations to Sayari Biswas, Exchange PhD student (ERASMUS), winner of the Nanoart Contest (Agust 2015), awarded by the Nanosciences Fondation. 





Congratulations to Shanting Zhang for the "Best student presentation award", sponsored by the Royal Society of Chemistry, E-MRS Fall meeting, symposium G!!!



Congratulations to Sayari Biswas, Exchange PhD student (ERASMUS) for the best oral presentation award in EuroCVD!!!!




Plenary lecture at the Thep-Center annual meeting, Krabi, Thailand, 21/05/2015




Member of the Scientific Committee, symposium G, E-MRS 2015 Fall Meeting:
“Transparent conductive materials: from fundamental understanding to applications” 
at the E-MRS 2015 Fall Meeting (15-18 September 2015, Tuesday-Friday) in Warsaw, Poland. 



Congratulations to Hongjun Liu, selected for the Kic Innoenergy doctorate program!!!

Co-organizer of RAFALD 


Participation in a Marie Curie EJD project :


Synthesis and modeling of uniform complex metal oxides by close-proximity atmospheric pressure chemical vapor deposition
ACS Appl. Mater. Interfaces, Just Accepted Manuscript 

Research update on ZnO deposited by Atmospheric Pressure Spatial Atomic Layer Deposition

"Atmospheric pressure spatial atomic layer deposition (AP-SALD) has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of APSALD
to deposit functional ZnO thin films, particularly on the reactors used, the film properties and the dopants that have been studied. We highlight how these films are advantageous for the
performance of solar cells, organometal halide perovskite LEDs and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a
sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics."




Co-organizer of symposium A1.1 Materials for Energy Harvesting, EUROMAT2015

International workshop on materials for energy
http://www.lmgp.grenoble-inp.fr/mat4energy-2014/welcome-574698.kjsp?RH=LMGP_EN-MAT4E-prog&RF=LMGP_EN-MAT4E-pres


MARIE CURIE "CAREER INTEGRATION GRANT" (CIG) Awarded to Dr. Muñoz-Rojas to carry out his research at the LMGP.


Minireview on novel spatial ALD for low-cost photovoltaics accepted in Materials Horizons


"Recently, a new approach to atomic layer deposition (ALD) has been developed that doesn't require vacuum and is much faster than conventional ALD. This is achieved by separating the precursors in space rather than in time.  This approach is most commonly called Spatial ALD (SALD). In our lab we have been using/developing a novel atmospheric SALD system to fabricate active components for new generation solar cells, showing the potential of this novel technique for the fabrication of high quality materials that can be integrated into devices. In this minireview we will introduce the basics of SALD and illustrate its great potential by highlighting recent results in the field of photovoltaics. "










Arrival at the LMGP highlighted in the February issue of MinaNews: 




Best Poster award at MC11, Energy Materials Theme.
Atmospheric Atomic Layer Deposition for Continuously Tuning the Metal Oxide Bandgap in ZnO – PbSe Quantum Dot Solar Cells, by Robert L. Z. Hoye et al. Congratulations ROBERT!



Best Poster award at ENMAT II
Functional Oxide Thin Films For New Generation Solar Cells Using Atmospheric Atomic Layer Deposition (AALD). by D. Muñoz-Rojas et al.





Finalist in the "Science as Art" competition, MRS Spring meeting, San Francisco, 2013
"Mitosis"





Atmospheric/Spatial Atomic Layer Deposition: towards cheaper, stable and efficient solar cells.


Ultrafast, spatial atmospheric atomic layer deposition (AALD), which does not involve vacuum steps and is compatible with roll to roll processing, is used to grow high quality TiO2 blocking layers for organic solar cells. Dense, uniform thin TiO2 films are grown at temperatures as low as 100 ˚C in only 37 seconds (~20 nm/min growth rate). Incorporation of these films in P3HT-PCBM based solar cells shows performances comparable to cells made using TiO2 films deposited with much longer processing times and/or higher temperatures.








Article on the groth of copper oxide by AALD has been highlighted in the journal webpage. 





Atmospheric/Spatial Atomic Layer Deposition: towards cheaper, stable and efficient solar cells. 


In low temperature grown ZnO/Cu2O solar cells, there is a discrepancy between collection length and depletion width in the Cu2O which makes the simultaneous achievement of efficient charge collection and high open-circuit voltage problematic. We address this in this study by fabricating ZnO/Cu2O/Cu2O+ back surface field devices using an atmospheric atomic layer deposition (AALD) printing method to grow a sub-200 nm Cu2O+ film on top of electrodeposited ZnO and Cu2O layers. The AALD Cu2O+ has a carrier concentration around 2 orders of magnitude higher than the electrodeposited Cu2O, allowing the electrodeposited Cu2O layer thickness in a back surface field cell to be reduced from 3 μm to the approximate charge collection length, 1 µm, while still allowing a high potential to be built into the cell. The dense conformal nature of the AALD layer also blocks shunt pathways allowing the voltage enhancement to be maintained. The thinner cell design reduces recombination losses and increases charge collection from both incident light and light reflected off the back electrode. Using this design, we achieve a short circuit current density of 6.32 mA cm-2 – the highest reported JSC for an atmospherically deposited ZnO/Cu2O device to date.

Advanced Functional Materials, accepted 2013







Work featured in the back cover of Journal of Materials Chemistry
 
 
 
 
WINNER OF 2011 MATERIALS TODAY COVER COMPETITION
 see also: 
Silver-copper mixed oxides. The unprecedented family.
D. Muñoz-Rojas*
 
PLATINUM 1st Poster Prize at the Nanotechnology for Sustainable Energy (ESF-FWF  conference in Partnership with LFUI). Universitätszentrum Obergurgl, Obergurgl, Austria, 4-9 July 2010. Sponsored by Energy & Environmental Science, Royal Society of Chemistry.