Improving the performance of 2D perovskite solar cells by carrier trappings and minifying the grain boundaries

Fabrication of 2D perovskite layers on 3D perovskite light absorbers, as the perovskite solar cells (PSCs), is being exploited to achieve a high power-conversion efficiency (PCE) along with promising long-term stability. However, to improve the performance of PSCs, an intermediate layer of smart material is required which can facilitate the desired interaction between two perovskite layers. The present work explores the role of 4-methoxyphenethylammonium (MPA+) cations as interfacing layer in 2D halide perovskite material towards developing an efficient PSCs. The effect of different ammonium salts (NH4Cl and NH4SCN) as additives in mixed halide MPA0.2MA0.8PbI3 is examined and the optoelectronic and photovoltaic responses of the developed PSCs are investigated in detail. Mixed halide MPA0.2MA0.8PbI3 thin film processed with NH4SCN additive showed an improved morphological and crystalline properties of fabricated PSCs as well as reduced non-radiative charge-carrier recombination rate. The NH4SCN/MPA0.2MA0.8PbI3 thin film based PSC demonstrated the highest PCE of ~15.1%, which is nearly 10% higher as compared to that of control PSC sample (~13.7%) and NH4Cl/MPA0.2MA0.8PbI3 thin film PSC (~7.53%). The NH4SCN/MPA0.2MA0.8PbI3 based PSC with highest efficiency, additionally showed a significantly improved device stability. It retained an efficiency value of ~95% of its initial even after exposure to ambient condition upto 300 h. The presented NH4SCN/MPA0.2MA0.8PbI3 thin film based PSC with high efficiency and high stability could open new avenues for improving the performance of solar cells and increase their contribution towards generation of renewable energy in future.