Conjugated Polyelectrolytes as Additives for Inverted Perovskite Solar Cell

Defects in perovskite solar cells (PSCs) significantly hinder their efficiency and stability. To tackle this challenge, our study explores the potential of two distinct π-conjugated polyelectrolytes (CPEs), MPS2-TEA and PCPDTBT2-TMA, as additives in PSCs. Unlike previous approaches where CPEs primarily served as interlayers or charge transporters, our focus is on their direct impact within the perovskite layer for defect passivation. Through thorough analysis, we observe that MPS2-TEA exhibits superior defect passivation compared to PCPDTBT2-TMA. This difference is attributed to the highly conductive nature of MPS2-TEA, enabling efficient mitigation of defects within the perovskite layer. In contrast, PCPDTBT2-TMA's self-doping effect, along with its negative sulfonate groups stabilizing polarons, reduces its effectiveness in defect passivation. The integration of MPS2-TEA into PSCs results in remarkable outcomes. The inverted perovskite solar cell with MPS2-TEA achieved notable power conversion efficiencies (PCEs) of 22.7% retaining over 87.3% of their initial PCE after 960 hours of continuous 1-sun illumination and maintaining 89% of PCE after 850 hours at 85°C in a nitrogen glovebox without encapsulation.