Multifunctional BODIPY-Structured n-Type Conjugated Polymer for Simultaneous Interface Energetic Modification and Defect Passivation to Boost Efficiency and Stability of Inverted Perovskite Solar Cells

The performance of inverted perovskite solar cells (PSCs) is hindered by non-radiative recombination within the perovskite and charge recombination at the cathode interface. To address these issues, we propose a technique involving oriented crystallization control and interface energetic modification using a conjugated thienyl-fused BODIPY homopolymer named IP1. IP1 demonstrated effectiveness in both defect passivation and energy level adjustment. Simultaneously, IP1 acts as a "protective shield" anchored on the grain boundaries and surfaces of perovskite, enhancing the crystal structure and preventing degradation of perovskite. Based on the efficient synergy above, the IP1-modified device achieves a high power conversion efficiency (PCE) of 25.06%, representing the highest value among n-type polymer-incorporated PSCs. More importantly, the IP1-modified device maintains 95% of its initial PCE after operating at the maximum power point (MPP) of 1000 h. This work combines achievements of n-type conjugated polymer science and interface energetic modification to open a new door for efficient and stable PSCs.