Halogen-free solvent processed organic solar sub-modules (≈55 cm2) with 14.70% efficiency by controlling the morphology of alkyl chain engineered polymer donor

Goals of high efficiency, morphological analysis, and the ability to produce organic solar cell (OSC) sub-modules using halogen-free solvents are demanding. In this study, a robust conjugated polymer with thienothiophene π-spacer with pendant alkyl side chain (NapBDT-C12) was synthesized and used to fabricate sub-modules. Excellent efficiencies were demonstrated by a NapBDT-C12 integrated ternary blend, which was used to produce stable small-area-to-sub-module devices using O-xylene. The efficiency of the NapBDT-C12 added small-area ternary devices (PM6:NapBDT-C12:L8-BO) was 18.71%. Owing to the controlled homogeneity of the blend with favorable nanoscale film morphology, enhanced carrier mobilities, and exciton dissociation/splitting properties, contributed to the efficiencies of small-area-to-sub-module OSCs. Moreover, a 55 cm² sub-module with an efficiency of 14.69% was accomplished by bar coating using O-xylene under ambient conditions. This study displays the potential of a ternary blend based OSC device to produce high efficiency scalable sub-modules at ambient conditions.