Computational study on the optical and NLO properties of donor–acceptor interaction molecules containing a triazolobenzothiadiazole or benzothiadiazole central acceptor core

Abstract

In this paper, based on the reported OTTAB, OTTTB and eight newly designed compounds, the DFT/TD-DFT theory is utilized to study the influence of the electron-accepting ability of the central core, the electron-accepting ability of the substituent and the substituent position on the frontier molecular orbital, electronic absorption, hole reorganization energy and second-order nonlinear optical (NLO) properties. This investigation reveals that replacing the left OT unit in OTTTB with an IC unit with an ethylene double bond is the most effective way to increase the maximum absorption peak, reduce the hole reorganization energy and enhance the second-order NLO properties. Considering that the studied compounds have a smaller hole reorganization energy and larger static first hyperpolarizability, they may become highly potential hole transport materials and strong second-order nonlinear materials.