Research

Research Interest

Research Experience

IUB Photonics Simulation Laboratory (IUBPSL)

Research Assistant, (RA) (January 2022 — Present)

Duration: 3.5 years

Worked on improving efficiency and light absorption of Cadmium Telluride (CdTe) and Si thin-film solar cells using nanostructures of different configurations embedded and on top
Worked on optimizing the performance of solar cells using metaheuristic algorithms, such as Particle Swarm Optimization
Carried out defect study of plasmonic metal nanoparticle arrays on the opto-electronic performance of thin-film solar cells
Mentored a group of six undergraduate students on research methodology and Lumerical application tools

Particle swarm optimization for performance enhancement of CdTe thin film solar cells embedded with plasmonic metal coated nano-grating structures

Abstract: This computational study investigates the potential performance enhancement of CdTe TFSCs consisting of an embedded SiO2 nano-grating structure with a thin aluminium coating layer. The purpose of this investigation was to use cost-effective grating materials that are easy to fabricate, without compromising on performance enhancement. Therefore, a thin plasmonic coating layer of aluminium was used on top of SiO2 nano-grating structure which stood out among other coating materials studied. Upon selecting the proper grating substrate and coating materials, initial simulations were done to find an optimal nano-grating period that provides necessary guided resonance for broadband absorption. The results reveal that the nano-grating period of 600 nm has the highest short-circuit current density of 29.24 mA/cm2 and efficiency of 22.29%, significantly higher than that of bare CdTe TFSCs. Subsequently based on these findings, Particle Swarm Optimization algorithm was used to optimize the height, angle, duty cycle, substrate thickness, and coating layer thickness of the nano-grating structures to push further the performance of CdTe TFSCs. The optimized nano-grating structure obtained resulted in a short-circuit current density and efficiency of 30.52 mA/cm2 and 23.48% respectively. Compared to bare CdTe TFSCs, short-circuit current density shows a 25.45% increase while efficiency shows a 52.86% increase, respectively. It is noteworthy that the optimal nano-grating structure shows insensitivity to the incident angle as elaborated in the later section, owing to its optimal period and aspect ratio. The viability of the proposed structure in terms of fabrication was also discussed. However, maintaining high precision in fabrication might add additional cost and reduce robustness. Recombination at the interface might also degrade the performance. Therefore, such limitations require extensive studies in the future to overcome. This work can also be extended by incorporating a 2D nano-grating structure and investigating other artificial intelligence or optimization algorithms to further improve the grating structure.

Effects of “defective” plasmonic metal nanoparticle arrays on the opto-electronic performance of thin-film solar cells

Abstract: This computational study investigates the effects of common defects that occur while fabricating arrays of plasmonic metal nanoparticles (NPs) on the absorbing layer of the solar cells for enhancing their opto-electronic performance. Several “defects” in an array of plasmonic NP arrays on solar cells were studied.

From the analysis of the results of the extensive investigations reported in this study, it can be observed that plasmonic TFSCs with various defects present in the nanoparticle array have comparable opto-electronic performance compared to solar cells coupled with a “perfect” array of “defect-free” nanoparticles. The opto-electronic performance levels of solar cells coupled to many kinds of such “defective” arrays of plasmonic nanoparticles is still significantly higher than that of a bare Si solar cell (i.e., with no coupled plasmonic nanoparticles). Thus, from this study, it can be concluded that relatively inexpensive and moderately low precision/low accuracy fabrication techniques can potentially be employed to fabricate plasmonic nanoparticles arrays (albeit with some defects) on TFSCs and still elicit significant enhanced performance levels from such solar cells. Thus, it might be possible to not be beholden to high accuracy, high-precision fabrication methods such as electron EBL and others, which are expensive and requires additional sophisticated clean room technology, in order to fabricate/manufacture effective “plasmonic” solar cells with enhanced opto-electronic performance parameters. The conclusion of this study suggests that it might be possible for research laboratories and semiconductor/electronics industries with limited access to large research funds (e.g., in developing countries) to fabricate such “defective” plasmonic nanoparticle arrays on solar cells with relatively low cost and still obtain significantly enhanced performance levels from such “plasmonic” solar cells. This can result in a wider use of TFSC systems leading to a significant drop in use of non-renewable energy sources (coal, petroleum, natural gas, etc.) and hence a cleaner, greener environment, and a progressive economy.

Plasmonic Metal Nanoparticles to Enhance The Opto-electronic Performance of Thin-Film/Ultrathin Film CdTe Solar Cells

Abstract: This computational study investigates ways to enhance the opto-electronic performance levels of CdTe TFSCs by coupling plasmonic silver nanoparticles on the CdTe absorbing substrate. The finite-difference time-domain (FDTD) numerical analysis technique has been used to analyze different performance parameters including short circuit current density (Jsc), open-circuit voltage (Voc), fill-factor, output power, efficiency and others. Furthermore, this study also compares the opto-electronic performance levels of “plasmonic” CdTe TFSCs with “plasmonic” amorphous Si TFSCs. Additionally, investigations of the robustness of “plasmonic” CdTe TFSCs due to temperature variation and the performance of ultrathin CdTe absorber layer (<250 nm thickness) is also presented. The results of this study show 13.47% increase in efficiency can be achieved for CdTe TFSCs by the use of plasmonic metal nanoparticles. Additionally, the results also strongly suggest that “plasmonic” CdTe TFSC performance levels are relatively stable across large temperature variations and can be up to 21 times more efficient than “plasmonic” Si TFSC for ultra-thin absorber layers.

Use of Embedded Nano-grating Structures to Optimize the Efficiency of Cadmium Telluride Thin-film Solar Cells

Abstract: This study computationally investigates the opto-electronic performance of Cadmium Telluride (CdTe) TFSCs with a metallic nano-grating structure embedded within the absorber layer. The finite-difference time-domain (FDTD) numerical analysis technique was used to computationally analyze different solar cell performance parameters with and without the nano-grating structure. Furthermore, an artificial intelligence (AI) technique, namely particle swarm optimization algorithm (PSO), was used to determine the optimum nano-grating configuration with respect to nano-grating height, angle, and duty cycle. The results suggest that the short circuit current density increased by 20.72%, while the solar cell efficiency yielded an increase of 21.66% for the Cadmium Telluride (CdTe) thin film solar cells (TFSCs) with the optimized nano-grating structure in comparison to a bare CdTe TFSC with no nano-grating. The results indicate that an important role can be played by such nano-grating structures to significantly enhance the opto-electronic performance of TFSCs, and this process can be optimized by the use of AI techniques.

Performance Enhancement of Cadmium Telluride Thin-film Solar Cells Using Nanocone-shaped Surface Texturing

Abstract: This study uses finite-difference time-domain (FDTD) numerical method to investigate the effect of nanocone-shaped texturing of the Cadmium Sulfide (CdS) window layer of CdTe TFSCs on the opto-electronic performance of such solar cells. The study aims to optimize the nanocone morphology, solar cell performance parameters such as short circuit current density (Jsc), open-circuit voltage (Voc), efficiency and others have been analyzed. The results suggest a 13.91% increase in Jsc and 14.13% efficiency enhancement can be achieved for nanocone texture having a diameter, height, and pitch of 600 nm, 400 nm, and 75 nm, respectively. Further comparison with plasmonic metal nanoparticle-incorporated CdTe TFSCs indicates surface texturing to be a preferable choice over plasmonic metal nanoparticles for efficient light trapping/absorption in TFSCs. This study shows the feasibility of using surface texturing at the nanoscale on the top surface of solar cells as an attractive option to increase incident light absorption (by reducing the reflection from the top surface) within the absorbing substrate (i.e., CdTe layer) and thus generating increased output current. Thus, CdTe TFSCs hold immense potential as a sustainable technology and contribute to efficient renewable energy production. Future studies will focus on optimizing multiple morphological parameters of the texturing structures.

Plasmonic Nanoparticles To Enhance The Optoelectronic Performance Of Lead-Free Formamidinium Tin Halide Perovskite Solar Cells

Abstract: This study aims to assess the scope of implementing plasmonic metal nanoparticles (NPs) in formamidinium tin iodide (FASnI3) perovskite solar cells (PSCs). The Finite-Difference Time-Domain (FDTD) method and Poisson continuity drift-diffusion equations were implemented using FDTD Solutions and CHARGE module from Ansys-Lumerical software suite. Nanoparticles (NPs) based on titanium (Ti), copper (Cu), gold (Au), silver (Ag), and aluminum (Al) were embedded at the center of the FASnI3 absorber layer, and the diameter of NPs was varied from 80 to 400 nm, keeping the inter-particle distance constant at 50 nm. Optoelectronic performance enhancement was observed for all NPs, with the optimal performance found for Ti NP at a diameter of 300 nm. The yielded short-circuit current density (Jsc) was 29.38 mA/cm2 compared to 21.90 mA/cm2 for bare FASnI3 PSC, and the optimal power conversion efficiency (PCE) was 22.85% compared to 17.28% for bare FASnI3. Interestingly, Cu NPs performed the second best with a Jsc of 28.06 mA/cm2 and PCE of 21.85% indicating the use of cheaper plasmonic NPs. This study indicated the potential of lead-free plasmonic FASnI3 PSC, which is crucial since lead is hazardous to animals and the environment. This study shows the possibility of using such plasmonic NP modified PSCs to power portable electronic devices.

Performance Enhancement of Thin-film Solar Cells Using Embedded Nanorods Comprised of Single-Walled Carbon Nanotubes (SWCNT)

Abstract: This computational study uses the Finite-Difference Time Domain (FDTD) method to investigate the opto-electronic performance of amorphous silicon thin-film solar cells (Si TFSCs) that are embedded with arrays of periodic nanorods composed of randomly oriented single-walled carbon nanotubes (SWCNTs). The diameter of the nanorods was varied between 20 nm and 70 nm, and for each diameter, the side-to-side distances between neighboring nanorods (pitch) were varied from 5 nm to 30 nm, keeping the nanorod height equal to the absorber layer thickness (550 nm). The optimal short circuit current density obtained was 32.13 mA/cm² for a nanorod diameter of 30 nm and pitch of 5 nm, yielding a 351% increase compared to bare Si TFSCs at 7.12 mA/cm². Additionally, the efficiency increased from 1.62% for bare Si TFSCs to 8.50% for the embedded SWCNT nanorod structure. This study shows the immense potential of using novel carbon-based nanostructures to significantly enhance the opto-electronic performance of solar cells, as well as contribute towards sustainable technology substituting fossil fuels to minimize global warming.

Systematic Study of Cadmium Telluride (CdTe) Thin-film Solar Cell Performance Optimization Using Spherical Plasmonic Metal Nanoparticles

Abstract: This computational study was conducted using the Finite-Difference Time-Domain (FDTD) method that used spherical plasmonic nanoparticles of various metals, e.g., silver, gold, aluminum, and titanium, and of different sizes coupled to the absorbing substrate of CdTe TFSCs to investigate their effect on the opto-electronic performance of the solar cells. The results show that the opto-electronic performance of CdTe TFSCs is significantly enhanced by most of the metal nanoparticles mentioned, with silver showing the most significant enhancement. It was observed that 150 nm diameter spherical silver nanoparticles placed on the top surface of CdTe TFSCs yield greater than 25% enhancement in the short-circuit current density (Jsc) when compared to bare CdTe TFSCs. It was also observed that the other performance parameters of CdTe TFSCs, such as open-circuit voltage, fill factor, output power, and efficiency, also show enhancements with the presence of spherical plasmonic metal nanoparticles. It is hoped that the encouraging results of this study can inspire exciting new research to significantly improve the opto-electronic performance of CdTe TFSCs using different innovative mechanisms.

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