Trilok_Singh_STEP

Arise! Awake! and stop not until the goal is reached

~Swami Vivekananda

Dr. Trilok Singh

Dr. Singh's group, Semiconductor Thin Film and Emerging Photovoltaic (STEP) Laboratory investigates new materials synthesis and material compositions for the applications in energy generation. In this area the main focus of our research is design and development of organic-inorganic metal halide perovskite materials for solar energy. The group aims to improve the understanding of the optoelectronic mechanisms responsible for the degradation of various components inside the perovskite device.

Current research areas :

Perovskite solar cell stability and efficiency
Solar driven water splitting and hydrogen production
Development of printable functional nanostructure materials for energy applications
Machine Learning and predictive analysis of PV systems

Crystallization modulation and interfacial treatment in anti-solvent free process for formamidinium-based perovskite solar cell, 2025, 165149.

Nitin Kumar Bansal, Shivam Porwal, Gyu-Min Kim, Trilok Singh*,

DOI: https://doi.org/10.1016/j.cej.2025.165149

The development of anti-solvent-free, additive-free, and ambient fabrication methods for formamidinium-based perovskite solar cells (PSCs) is crucial for the successful commercialization of this emerging solar cell technology. Herein, a conjugate organic polymer Poly(9,9-bis(3′-(N,N-dimethyl)-N-ethylammoinium-propyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene))dibromide (PFNBr) is utilized at the interface of tin oxide electron transport layer (SnO2 ETL) and formamidinium lead tri-iodide perovskite (FAPbI3) to address the issue of interfacial defects. Further, the incorporation of PFNBr during anti-solvent-free deposition facilitates better crystallinity of FAPbI3 films which subsequently mitigate non-radiative recombination losses by passivating interfacial defects and enhanced the device performance (efficiency >22.5%). The stability study shows improved device performance after 2000 h of periodic measurement, the PFNBr device maintained over 90% of its initial PCE. Thus, the interfacial modifications in an anti-solvent-free process effectively improve the structural and functional properties of the absorber layer, which subsequently addresses the issues of film non-uniformity and poor reproducibility of PSCs produced in ambient conditions.

Effect of Guanidinium Salt for Stress-Relaxation and Interfacial Engineering in Antisolvent Free Perovskite Solar Cells Fabricated Under Air Ambient, Small, 2024, xx.

Shivam Porwal, Nitin Kumar Bansal, Gyu Min Kim, Trilok Singh*

DOI: 10.1002/smll.202408168

In perovskite solar cells, the presence of stress and defects at interfaces promotes performance degradation and poor stability of the devices. The formation of these defects is more prominent in two-step antisolvent-free perovskite film fabrication. This study addresses these challenges by introducing guanidine sulfate (Gua-S) at the tin oxide/formamidinium lead iodide perovskite interface, fabricated without antisolvent under ambient air. Interfacial Gua-S enhanced morphology by forming bonds between uncoordinated Pb2+ ions and I- vacancies at the interface and showed improvement in the crystallinity and quality of the perovskite film. Microstructural stress analysis indicated a substantial reduction in stress, decreasing from 50.6 to 20.72 MPa with the application of Gua-S. Moreover, the Gua-S treated solar cells showed significant improvements and achieved an open circuit voltage of 1.08 V and 22.34% efficiency. Further, electrochemical impedance spectroscopic analysis showed improved built-in potential, carrier lifetime, and charge recombination lifetime for treated devices. The devices retained over 87% of the initial power conversion efficiency after 2000 hours of operation. This comprehensive study addresses the fundamental issues of interfacial stress and defects in perovskite solar cells and demonstrates the efficacy of Gua-S salt in enhancing both the structural and functional aspects of the antisolvent-free device fabrication process.

Role of ionic liquids in organic-inorganic metal halide perovskite solar cells efficiency and stability, Nano Energy, 2019

Subrata Ghosh and Trilok Singh

https://www.sciencedirect.com/science/article/pii/S2211285519305282

Organic-inorganic metal halide perovskite solar cells (PSCs) are developing in a rapid pace as a potential energy harvesting material. Within a short time span it has achieved the power conversion efficiency comparable to the similar mature technologies (crystalline Silicon, CIGS, CdTe etc.) available in the market. Unfortunately, PSCs have stability issues in real time operating conditions and posed a hurdle towards its commercialization. Various modifications and engineering aspects have been applied so far to cope up with this issue and among these players, ionic liquids (ILs) have certainly grabbed the attention of the researchers recently. ILs have unique and versatile properties like high ionic conductivity, thermal and electrochemical stability; which are suitable for application in PSCs. This review describes the fundamental, present status and future prospectus of role of ILs in perovskite solar cells focussing on the stability and efficiency. Strategies regarding surface/interface modifications, engineering of interfaces and interaction of ions (cations/anions) from ILs with various perovskite precursors are discussed.

Stabilizing the Efficiency Beyond 20% with a Mixed Cation Perovskite Solar Cell Fabricated in Ambient Air under Controlled Humidity, Advanced Energy Materials (2018)1700677

https://onlinelibrary.wiley.com/doi/10.1002/aenm.201700677

Trilok Singh and Tsutomu Miyasaka

Perovskite solar cells have evolved to have compatible high efficiency and stability by employing mixed cation/halide type perovskite crystals as pinhole‐free large grain absorbers. The cesium (Cs)–formamidium–methylammonium triple cation‐based perovskite device fabricated in a glove box enables reproducible high‐voltage performance. This study explores the method to reproduce stable and high power conversion efficiency (PCE) of a triple cation perovskite prepared using a one‐step solution deposition and low‐temperature annealing fully conducted in controlled ambient humidity conditions. Optimizing the perovskite grain size by Cs concentration and solution processes, a route is created to obtain highly uniform, pinhole‐free large grain perovskite films that work with reproducible PCE up to 20.8% and high preservation stability without cell encapsulation for more than 18 weeks. This study further investigates the light intensity characteristics of open‐circuit voltage (Voc) of small (5 × 5 mm2, PCE > 20%) and large (10 × 10 mm2, PCE of 18%) devices. Intensity dependence of Voc shows an ideality factor in the range of 1.7‐1.9 for both devices, implying that the triple cation perovskite involves trap‐assisted recombination loss at the hetero junction interfaces that influences Voc. Despite relatively high ideality factor, perovskite device is capable of supplying high power conversion efficiency under low light intensity (0.01 Sun) whereas maintaining Voc over 0.9 V.

Role of ionic liquids in organic-inorganic metal halide perovskite solar cells efficiency and stability, Nano Energy, 2019

Subrata Ghosh and Trilok Singh

https://www.sciencedirect.com/science/article/pii/S2211285519305282

Organic-inorganic metal halide perovskite solar cells (PSCs) are developing in a rapid pace as a potential energy harvesting material. Within a short time span it has achieved the power conversion efficiency comparable to the similar mature technologies (crystalline Silicon, CIGS, CdTe etc.) available in the market. Unfortunately, PSCs have stability issues in real time operating conditions and posed a hurdle towards its commercialization. Various modifications and engineering aspects have been applied so far to cope up with this issue and among these players, ionic liquids (ILs) have certainly grabbed the attention of the researchers recently. ILs have unique and versatile properties like high ionic conductivity, thermal and electrochemical stability; which are suitable for application in PSCs. This review describes the fundamental, present status and future prospectus of role of ILs in perovskite solar cells focussing on the stability and efficiency. Strategies regarding surface/interface modifications, engineering of interfaces and interaction of ions (cations/anions) from ILs with various perovskite precursors are discussed.

Stabilizing the Efficiency Beyond 20% with a Mixed Cation Perovskite Solar Cell Fabricated in Ambient Air under Controlled Humidity, Advanced Energy Materials (2018)1700677

https://onlinelibrary.wiley.com/doi/10.1002/aenm.201700677

Trilok Singh and Tsutomu Miyasaka

Perovskite solar cells have evolved to have compatible high efficiency and stability by employing mixed cation/halide type perovskite crystals as pinhole‐free large grain absorbers. The cesium (Cs)–formamidium–methylammonium triple cation‐based perovskite device fabricated in a glove box enables reproducible high‐voltage performance. This study explores the method to reproduce stable and high power conversion efficiency (PCE) of a triple cation perovskite prepared using a one‐step solution deposition and low‐temperature annealing fully conducted in controlled ambient humidity conditions. Optimizing the perovskite grain size by Cs concentration and solution processes, a route is created to obtain highly uniform, pinhole‐free large grain perovskite films that work with reproducible PCE up to 20.8% and high preservation stability without cell encapsulation for more than 18 weeks. This study further investigates the light intensity characteristics of open‐circuit voltage (Voc) of small (5 × 5 mm2, PCE > 20%) and large (10 × 10 mm2, PCE of 18%) devices. Intensity dependence of Voc shows an ideality factor in the range of 1.7‐1.9 for both devices, implying that the triple cation perovskite involves trap‐assisted recombination loss at the hetero junction interfaces that influences Voc. Despite relatively high ideality factor, perovskite device is capable of supplying high power conversion efficiency under low light intensity (0.01 Sun) whereas maintaining Voc over 0.9 V.

Antisolvents in Perovskite Solar Cells: Importance, Issues, and Alternatives

Subrata Ghosh Snehangshu Mishra and Trilok Singh

Advanced Materials Interface , 8/2020, doi.org/10.1002/admi.202000950

Organic–inorganic metal halide perovskite solar cells are emerging as potential solar energy harvesting tools and can be a tough competitor to already matured solar cell technologies. The success of perovskite solar cells is attributed to superior optoelectronic properties of perovskites, feasible synthesis process, and low fabrication cost. Though perovskite solar cells confront perovskite film quality related issues, such as rough surface, pinholes (which result in poor device performance) at the initial stages, many techniques have been developed to improve the perovskite film quality. Among these developed techniques, the antisolvent treatment method is certainly one of the most successful techniques till date. Antisolvent treatment increases the nucleus density during film formation to produce uniform and pinhole‐free perovskite film, which facilitates improved solar cell efficiency, low hysteresis, and stability. Interestingly, many of the best efficiency perovskite solar cells till date have been produced by the antisolvent treatment. This review discusses the fundamentals of antisolvent treatment, various aspects of antisolvent application on perovskite film, different issues with antisolvent usage, and alternatives techniques for perovskite film quality improvement.