Ground-State Orbital Analysis Predicts S₁ Charge Transfer in Donor-Acceptor Materials

Donor-acceptor (D-A) materials can exhibit a wide range of unique photophysical properties with applications in next-generation optoelectronics. Electronic structure calculations of D-A dimers are often employed to predict the properties of D-A materials. One of the most important D-A dimer quantities is the degree of charge transfer (DCT) in the S₁ state, which correlates with properties such as fluorescence lifetimes and intersystem crossing rates in D-A materials. While predictive metrics of the S₁ DCT generally require an excited-state quantum chemistry calculation, presented here is a novel metric that predicts S₁ DCT solely with ground-state orbital analysis. This metric quantifies the similarity of the orbitals between a dimer complex and its monomer components. A linear relationship is found between this similarity metric and the S₁ DCT, calculated using a data set of 31 D-A dimers. Best practices for integrating this novel orbital structure-function relationship into high-throughput screening methods are discussed.