Polysulfide Chain-Length Tuning of Poly(anthraquinonyl sulfides) to Enhance Crystallization, Defect Passivation, and Environmental Stability of Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) have achieved rapid gains in power conversion efficiency (PCE), yet their broader deployment remains limited by insufficient stability and Pb-leakage concerns. Anthraquinone-based materials are attractive interfacial modifiers, with their carbonyl groups providing Lewis-base sites for passivating undercoordinated Pb-related defects and potential binding sites for Pb immobilization, their π-conjugated aromatic structures facilitating interfacial charge transport, and their redox-active quinone moieties helping suppress degradation-related Pb and iodine species. However, these materials have predominantly been explored as small-molecule additives or interfacial passivators, while their use as polymeric antisolvent additives and the influence of polymer structural characteristics on perovskite properties remain largely unexplored. Herein, we synthesized poly(anthraquinonyl sulfides) (PAQxS), in which anthraquinone units are connected by sulfur-containing linkages that provide conformational freedom and potential soft-donor functionality, and investigated their application as antisolvent additives for PSCs. To examine how these linkage characteristics affect polymer–perovskite interactions, we compared two representative polymers, PAQdS and PAQnS, with relatively shorter and longer sulfur-linkage distributions, respectively. Compared with PAQdS, PAQnS promoted more ordered perovskite crystallization and improved film morphology, accompanied by lower trap density, reduced defect-related carrier losses, and improved charge-carrier behavior. These improvements in film and interfacial properties were associated with an approximately 20% relative increase in PCE, together with a markedly prolonged T80 lifetime and an approximately 40% reduction in Pb leakage. Overall, this study demonstrates the potential of sulfur-linked anthraquinone-based polymers as a structure-guided platform for improving photovoltaic performance, stability, and Pb-leakage mitigation in PSCs while providing insight into structure-dependent film and interfacial behavior.