Acridine-Substituted-Centronucleus Nonfullerene Acceptors Enables Organic Solar Cells with Over 20% Efficiency with Low Nonradiative Recombination Loss.

In this work, we propose a novel strategy of introducing luminescent acridine units for central nuclear substitution in quinoxaline-based acceptor molecules (named AQx-o-Ac and AQx-m-Ac) to enhance their photoluminescence quantum yields (PLQY), which can effectively improve the electroluminescent quantum efficiency (EQE) of OSCs and thereby suppress ΔE. In addition, the substituted acridine unit accelerates molecular aggregation and optimizes molecular crystallization, effectively alleviating the static disorder of acceptor molecules and facilitating charge extraction and transport in OSCs. As a result, the PM6:AQx-m-Ac binary OSCs achieve an excellent PCE of 18.64% with an exceptionally low ΔE of 0.166 eV. To the best of our knowledge, a ΔE of 0.166 eV represents the lowest value reported for OSCs achieving PCEs over 18 %. Finally, the acceptor AQx-m-Ac is incorporated into PM6:eC9 blend as the third component, and the optimal ternary device produces a superior PCE of 20.28%. This work highlights the potential of promoting luminescence for suppressing nonradiative energy loss and charts a viable path for upcoming breakthrough in high-efficiency organic photovoltaics.