Liquid‐State Dithiocarbonate‐Based Polymeric Additives with Monodispersity Rendering Perovskite Solar Cells with Exceptionally High Certified Photocurrent and Fill Factor

Abstract Dithiocarbonate‐based non‐hygroscopic polymers with a glass transition temperature (Tg) and polydispersity index (PDI) of ≈4 °C and 1, respectively, are synthesized through living cationic ring‐opening polymerization. These liquid‐state polymers are characterized by monodispersity based on the low Tg and PDI, rendering remarkable miscibility with the perovskite precursors without aggregation. Accordingly, these polymers are added to perovskite solar cells (PSCs) to enhance their power conversion efficiency (PCE). The PCE of reference PSCs increases from 19.70% to 23.52% after direct addition of the synthesized polymer. This efficiency improvement is attributed to the considerable increases in short‐circuit current density (JSC) and fill factor (FF), resulting from the augmented size and defect passivation of perovskite crystals induced by added polymers. In fact, the PCE and JSC…