The effect of heteroatoms at end groups of anthracene derivatives on the photoelectric properties and crystal/film morphology: a theoretical perspective

Abstract

Three anthracene derivatives with a 2,6-diphenylanthracene core and C-, O-, and S-bridged alkyl chain substituents (BEPAnt, BOPAnt, and BSPAn) exhibit relatively balanced high luminescence and mobility properties, and can be candidates for organic light-emitting transistor device materials. The optoelectronic properties including charge transport and fluorescent properties of three anthracene derivatives were investigated via quantum chemistry calculations. The results show that BEPAnt and BOPAnt exhibit high hole mobility (3.60 and 1.35 cm² V⁻¹ s⁻¹) and blue emission fluorescence quantum yield (>60%). In addition, the growth morphology of crystals/films can affect their properties, especially charge transport behavior but is often overlooked in theoretical evaluation. Hence, the morphological evolution of their organic thin-film is characterized by the attachment energy (AE) model. The predicted morphologies for BEPAnt and BOPAnt are consistent with the shape of their single-crystal films using the physical vapor transport (PVT) technique. The phenomenon of in-plane growth ratios for BEPAnt and BOPAnt crystal facets is reproduced well using the AE model. Notably, symmetrical hydrogen bond interactions within and between crystal layers facilitate the formation of a large flat film such as BOPAnt, which is conducive to better performance of charge transport properties in the experiment. We hope that this study can clearly provide details on the driving forces that affect the crystal surface growth rate, and then provide valuable guidance for the design and regulation of organic semiconductor molecules with ideal crystal morphology.