Dithienopyrrolothiophene (DTPT) Based Acceptors for Fine-Tuning Molecular Packing and Enhancing Ternary Organic Photovoltaic Performance

Abstract

The ternary strategy boosts the performance of organic photovoltaics (OPVs) by optimizing light-harvesting, energy level alignment, and blend morphology. Herein, three non-fullerene acceptors (NFAs), IN-DTPT-b20 (1), INF-DTPT-b20(2) and INCl-DTPT-b20 (3) a featuring dithienopyrrolothiophene (DTPT) based fused ring core with soluble branched alkyl side chains with indanone (IN), and its fluoro-(INF) and chloro-(INCl) derivatives as an electron-accepting end group have been rationally designed and synthesized from simple and readily available starting materials. The thermal, optical, electrochemical, and computed electronic structural properties of 1-3 were investigated and contrasted. We investigate the optoelectronic properties of PM6:Y6 based OPV in the presence of 1-3 as third component. Following optimization, the power conversion efficiency (PCE) increased from 15.17±0.28% for the PM6:Y6 based OPV to 16.20±0.26% for the IN-DTPT-b20 (1) derived ternary OPV. Tapping-mode atomic force microscopy (AFM) and grazing-incidence wide-angle X-ray scattering (GIWAXS) analysis confirmed that incorporating IN-DTPT-b20 (1) into PM6:Y6 blend films effectively tailored the blend morphology, particularly by modulating the preferred orientation of Y6. The optimized morphology resulted in enhanced carrier mobility, reduced trap-assisted recombination, and efficient charge collection. These findings demonstrate the effectiveness of our NFA design strategy, further bolstered by the incorporation of IN-DTPT-b20 (1) as a guest acceptor, for achieving efficient OPV.