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

摘要

Dithiocarbonate-based non-hygroscopic polymers with a glass transitiontemperature (T_g) and polydispersity index (PDI) of ≈4 ℃ and 1, respectively,are synthesized through living cationic ring-opening polymerization. Theseliquid-state polymers are characterized by monodispersity based on the lowT_g and PDI, rendering remarkable miscibility with the perovskite precursorswithout aggregation. Accordingly, these polymers are added to perovskitesolar cells (PSCs) to enhance their power conversion efficiency (PCE). ThePCE of reference PSCs increases from 19.70% to 23.52% after direct additionof the synthesized polymer. This efficiency improvement is attributed tothe considerable increases in short-circuit current density (J_(SC)) and fill factor(FF), resulting from the augmented size and defect passivation of perovskitecrystals induced by added polymers. In fact, the PCE and J_(SC) of the devicesmeasured in the laboratory and the certification center are the highest amongthe reported polymer-added PSCs, thanks to the great miscibility of the newpolymers leading to the large amount addition which enables more thoroughpassivation among the grain boundaries. The improvement in open-circuitvoltage falls short as compared to that in J_(SC) and FF, ascribed to the relativelymoderate interaction strength between perovskite materials and dithiocarbonategroups.