17.5% Efficiency of Polythiophene-based Solar Cell Enabled by Trialkylsilyl-thienothiophene-grafted Acceptor

초록

Despite significant progress in the power conversion efficiency (PCE) of polythiophene-based organic solar cells (PT-OSCs), their suboptimal blend morphology remains challenging to overcome when paired with prevailing non-fullerene acceptors (NFAs). Herein, a new trialkylsilyl-thieothiophene grafted NFA, named Y-TTsi, is proposed, featuring a distinctly twisted backbone conformation, a high dipole moment, and well-defined "face-on" packing. Leveraging the trialkylsilyl-thienothiophene grafted pendant, Y-TTsi was introduced into the classical PT-OSCs system (PTVT-T:Y6-BO-4Cl) as the third component to fine-tune intermolecular interactions. It is found that synergetic yet opposite intermolecular interactions of Y-TTsi with the PTVT-T polymer donor and Y6-BO-4Cl acceptor effectively reassemble miscibility strength, molecular aggregation, and film crystallinity. Benefiting from the improved exciton dissociation and charge transfer, the resultant PTVT-T:Y6-BO-4Cl: Y-TTsi-based ternary PT-OSCs afford a decent PCE of 17.5% with a short-circuit current density of 27.78 mA/cm2, open-circuit voltage of 0.803 V, and fill factor of 0.786. More importantly, the incorporation of Y-TTsi resulted in reduced energy loss in the resultant ternary device by simultaneously mitigating both radiative and non-radiative recombination. This study highlights not only the newly designed trialkylsilyl-thienothiophene grafted NFA but also its effects on refining intermolecular interactions in the PT-OSCs system toward minimized energy loss and ideal blend morphology.

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