Chalcogen-substituted PCBM derivatives as ternary component in PM6:Y6 solar cells

Ternary organic solar cells (TOSCs) are a promising approach to enhance power conversion efficiency in organic-based solar cells. The combination of fullerene and non-fullerene acceptors works to optimize the light absorption and phase separation for better charge dissociation and collection. Herein, we describe the synthesis and characterization of three chalcogens substituted PCBM derivatives with a 5-membered aromatic ring linked to the methyl ester position with the objective to study the relationship between interphase separation and power conversion efficiency. Therefore, the effect of furan, thiophene and selenophene in the PCBM derivatives (PCBFu, PCBTh and PCBSe, respectively) are investigated on the photovoltaic performance of ternary organic solar cells based on PM6:Y6. We observed that the addition of the PCBTh and PCBSe derivatives increase the short circuit current density and the fill factor pointing to the suppression of charge recombination. In addition, surface analysis confirms that the morphology is optimized in both cases, which implies that organized thin film nanomorphology is key for supression of carrier losses. The TOSC with PCBTh exhibited the highest power conversion efficiency among all the devices reaching 14.6%