Shanghai Jiao Tong University’s Liu Feng Team Reports in Joule: High-Efficiency, Stable High-Entropy Organic Photovoltaic Cells

Organic photovoltaics (OPV) currently suffer from the inability to simultaneously achieve high efficiency and long-term stability, posing a major challenge to their commercialization. In response, a team led by Feng Liu, Shengjie Xu, and Ming Zhang at Shanghai Jiao Tong University has introduced a high-entropy (HE) approach that combines physical blending with chemical synthesis to mix multiple components and thereby increase system entropy; the relevant findings have been published in the journal Joule. The team’s results demonstrate that, owing to the identical acceptor backbone, physically blended HE mixtures retain strong π–π interactions. By introducing different halogen atoms or alkyl chains, structural order is reduced, leading to an optimal blend in which the density of states in the conduction band is redistributed, resulting in a larger effective bandgap, reduced nonradiative recombination, and an increased open-circuit voltage. This HE design principle was then extended to chemical synthesis to fabricate HE materials, yielding a maximum power conversion efficiency of 20.6% (20.3% ± 0.2%, certified as 20.0%) in OPV devices. Furthermore, both operational and thermal stability, as measured under continuous illumination in conventionally encapsulated devices, were significantly improved.