Single-layered organic solar cells (OSCs) based on non-fullerene acceptors (NFAs) have been widely concerned attribute to the rapid progress in power conversion efficiency (PCE), which benefits from the continuous optimization of the electronic structure of the materials and the device structures. However, the performance of OSCs is still far behind other photovoltaic devices based on inorganic materials. One fundamental reason is the low charge mobility of organic materials and the complexity of non-equilibrium morphology of optical absorption layer. The next generation of NFA represented by Y6 shows better electronic structure, appropriate frontier energy levels and well matching with various donor materials. The efficiency of Y6-based OSCs has exceeded 18% and maintains a strong upward trend, envisaging a prosperous future for the OSC technology. As a derivative of Y6, the electronic structure of L8-BO was further optimized and the better morphology of the bulk heterojunction (BHJ) blends based on PM6:L8-BO improved the generation and transmission of carriers and reduced the charge recombination, achieving a PCE approaching 19%. The details of optimized multi-length scaled morphology is the key to improving device performance. In this optimized morphology framework, a global match between the photoelectric parameters and the characteristic lengths is realized, leading to effective exciton separation and the efficient carrier transport.
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