Investigation of linear and second-order nonlinear optical properties of donor-acceptor interaction derivatives based on acceptor DCPPr core

Abstract

Red thermally activated delayed fluorescence (TADF) materials have attracted much attention from researchers due to their potential applications in display and lighting devices. Recently, DCPPr-TPA has displayed unique photophysical properties, such as high optical out-coupling factor and near infrared (NIR) emissions. However, its structure-property relationship has not been fully detected, which will further improve their performance. Herein, based on the reported DCPPr-TPA, four new derivatives are designed by inserting π-bridge ethylene units, introducing donor NO2 units or acceptor NH2 units, and replacing TPA unit with NI unit. Their linear and second-order nonlinear optical properties are investigated in detail using DFT and TD-DFT theories. It is concluded that the insertion of π-bridge ethylene units and the introduction of the donor NH2 units on TPA units are the most effective methods to reduce the energy gap, redshift the maximum absorption wavelength and increase the first hyperpolarizability. The four newly designed derivatives do not further enhance hole transport ability, but derivatives 1–3 do enhance electron transport ability, and derivatives 1–3 are all potential bipolar transport materials. In view of their large first hyperpolarizability, the studied derivatives may become second-order nonlinear optical (NLO) materials with excellent properties.