2D/3D heterojunction engineering at the grain boundaries towards high-performance inverted MA-free perovskite solar cells

The construction of multidimensional (2D/3D) heterojunction perovskites as light-harvesting layers has emerged as one of the most dependable strategies for stabilizing perovskite solar cells (PSCs) without compromising their photovoltaic performance, amidst the plethora of stability-enhancing techniques that have been reported. Herein, we have identified a 2D/3D heterojunction perovskite of FAPbI3, which is based on a small molecular Pivalimidamide hydrochloride and has demonstrated the ability to effectively enhance both the efficiency and stability of PSCs. Device characterizations have revealed that the 2D/3D structure modification improves the fluorescence lifetime, decrease grain boundaries (GBs) defects and ultimately results in achieving efficiencies of 22.06% based on CsFAPbI3. The introduction of the 2D layer improves film uniformity and inhibit phase separation as verified by photoluminescence measurement. Unencapsulated devices were stored at room tempera-ture under N2 conditions for 1000 h, with 92% of the initial efficiency. It remains 80% of its initial efficiency after continuous operation under illumination at the maximum power point and at a temperature of 40 degrees C for over 440 h.