Design, synthesis and photophysical investigation of triphenylamine-bithiophene dyes as RGB emitters for white light applications

Abstract

A set of three triphenylamine-bithiophene based Donor-Acceptor (D-A) molecules viz. TPT, TPT-Ben and TPT-Ac were designed, synthesized and studied for their photophysical properties. Systematic density functional theory (DFT) calculations have been performed on the molecules to gain insights into the structural, electronic and optical properties. The nanosecond transient absorption spectra showed broad absorption due to the presence of triphenylamine radical cation with an average time constant of 3.5 μs The molecules were found to emit in the Blue, Green and Orange-Red regions of the visible spectrum due to the differences in their Stokes shift values. A 3:2:1 mixture of TPT, TPT-Ben and TPT-Ac gave white light emission with a colour coordinate of (0.32, 0.36) even at an μM level concentration in both solution state (DMSO) as well as in the solid state (0.33,0.37).