The solar power conversion efficiencies of organic solar cells (OSC) have now increased up to 19%, closing the gap with inorganic and hybrid solar cells. The major breakthrough behind the rapid efficiency improvement is the development of non-fullerene acceptor molecules, replacing the traditional fullerene molecules as electron-accepting materials. Understanding the photophysical processes underlying these high-performance materials is crucial to OSC research. In this talk, I will present transient optical spectroscopy and structural analysis results on high-performance OSC blends based on state-of-the-art Y-type small molecule and polymeric acceptors. We find direct evidence that the interfacial D-A percolation plays a key role in suppressing interfacial charge recombination to enable efficient charge generation, and such morphology greatly improves the thermodynamic stability of the blend. Furthermore, we uncovered a new all-optical method for predicting the OSC performance of acceptor molecules, which will be a valuable tool for future material design and screening.

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Philip Chow, "Engineering ultrafast exciton dynamics to boost organic photovoltaic performance," Proc. SPIE 13123, Organic, Hybrid, and Perovskite Photovoltaics XXV, 131230V (Presented at Organic Photonics + Electronics: August 22, 2024; Published: 30 September 2024); https://doi.org/10.1117/12.3025211.ec4d476b-dfaa-ee11-a99d-c49c781f4d15.