Self-Assembled Donor–Acceptor Chromophores: Evident Layer Effect on the First Hyperpolarizability and Two-Dimensional Charge Transfer Character

Abstract

Self-assembled donor–acceptor chromophores have extensive applications in photofunctional devices owing to their unique charge transport properties. To explore the possibility of improving nonlinear optical (NLO) properties by self-assembly to multilayer complexes, we theoretically investigated the geometric and electronic structures, interlayer weak interactions, absorption spectra, charge transfer properties, polarizabilities (α), and first hyperpolarizabilities (β) of naphthalimide, -phenyl, and -naphthyl monomers, dimers, and trimers by increasing the layer number n (n = 1, 2, 3). Different stacking patterns of their dimers were also taken into account. These show that parallel stacking patterns are conducive to maximizing overlap with respect to antiparallel ones due to the concept of optimal π-orbital overlap is more vast than purely maximizing cofacial overlap to improve charge transport. The decreases in band gap for the di/trimeric versus monomeric naphthalimide, -phenyl, and -naphthyl monomers i...