Perovskite solar cells (PSCs) have shown impressive efficiency due to their d irect bandgap, low exciton binding energy, low processing temperature, ambipolar nature, and excellent optoelectronic properties. However, their rapid degradation in ambient conditions, especially when exposed to moisture, hinders their real-world testing and deployment(Battula, Sudakar, et al. 2022). My research focuses on understanding the stability aspects of Methyl ammonium lead iodide (MAPbI3) based PSCs and providing suitable solutions to enhance the efficiency. Strategies to improve the ambient stability of n-i-p architecture MAPbI3-based PSCs are addressed by (i) hole transport material (HTM) modification, (ii) grain boundary engineering, and (iii) precursor purity engineering. Inorganic CuSCN as an alternative to the organic HTM which suppresses easy moisture penetration is demonstrated. By modifying the hole transport layer in the PSCs, a power conversion efficiency (PCE) of 10% and stability for 1500 h under ambient conditions (25±3 °C and 50±10% RH) is obtained(Battu la, Veerappan, et al. 2022). Grain boundaries in the perovskite absorber layer, which act as active sites for moisture penetration, are engineered to improve the stability further. Large-grained MAPbI3 films with 100 times larger grain size than conventional films are fabricated using the inverse temperature crystallization technique. With these films stability of 5000 h with a modest PCE of 3.2% under ambient conditions is achieved(Battula et al. 2020). A novel technique employing single crystals is designed to draw a consensus between efficiency and stability. Improving the precursor purity of MAPbI3 ink, used to fabricate perovskite films, played a crucial role in enhancing both efficiency and stability. A PCE of 16.7% with stability of 3500 h under ambient conditions is achieved by obtaining the precursor ink from single crystals through a vapor-mediated approach(Battula et al. 2023). In this talk, I will present a comprehensive approach to improving the stability of PSCs whi le maintaining a reasonable level of PCE by employing these strategies. These advancements are crucial for making perovskite solar cells viable for outdoor applications where various environmental conditions over extended periods are unavoidable.
Battula, Ramya Krishna et al. 2020. “Stability of MAPbI 3 Perovskite Grown on Planar and Mesoporous Electron-Selective Contact by Inverse Temperature Crystallization.” RSC Advances 10(51): 30767–75. http://xlink.rsc.org/?DOI=D0RA05590E.
Battula, Ramya Krishna, Ganapathy Veerappan, et al. 2022. “Dual Functional Inorganic CuSCN for Efficient Hole Extraction and Moisture Sealing of MAPbI3 Perovskite Solar Cells.” Materials Advances. http://pubs.rsc.org/en/Content/ArticleLanding/2022/MA/D1MA00861G.
Battula, Ramya Krishna, Chandran Sudakar, et al. 2022. “Single-Crystal Hybrid Lead Halide Perovskites: Growth, Properties, and Device Integration for Solar Cell Application.” Crystal Growth & Design 22(10): 6338–62. https://pubs.acs.org/doi/10.1021/acs.cgd.2c00789.
Battula, Ramya Krishna et al. 2023. “MAPbI3 Single Crystal Derived Precursor Ink for Stable and Efficient Perovskite Solar Cells.” Journal of Alloys and Compounds 944: 169082. https://linkinghub.elsevier.com/retrieve/pii/S0925838823003857.
PhD Scholar, Department of Physics, IIT Madras