Tailoring pyridine bridged chalcogen-concave molecules for defects passivation enables efficient and stable perovskite solar cells
Muhammad Azam, Yao Ma, Boxue Zhang, Xiangfeng Shao, Zhongquan Wan, Huaibiao Zeng, Haomiao Yin, Junsheng Luo, Chunyang Jia
Abstract
Suppressing deep-level defects at the perovskite bulk and surface is indispensable for reducing the non-radiative recombination losses and improving efficiency and stability of perovskite solar cells (PSCs). In this study, two Lewis bases based on chalcogen-thiophene (n-Bu4S) and selenophene (n-Bu4Se) having tetra-pyridine as bridge are developed to passivate defects in perovskite film. The uncoordinated Pb2+ and iodine vacancy defects can interact with chalcogen-concave group and pyridine group through the formation of the Lewis acid-base adduct, particularly both the defects can be surrounded by concave molecules, resulting in effective suppression charge recombination. This approach enables a power conversion efficiency (PCE) as high as 25.37% (25.18% certified) for n-i-p PSCs with stable operation at 65 °C and 1-sun illumination for 1300 hours in N2 (ISOS-L-2 protocol), retaining 94% of the initial efficiency. Our work provides insight into the bowl-shaped Lewis base in defects passivation by coordinated strategy for high-performance photovoltaic devices. Suppressing deep-level defects at the perovskite bulk and surface is critical to reduce the non-radiative recombination losses in perovskite solar cells. Here, authors employ concave-shaped chalcogen molecules for defect passivation, achieving certified efficiency of 25.18% for stable n-i-p devices.