Insight into Triphenylamine Donor Thiazole Acceptor Conjugated Oligomer to Analyze Emission Behavior towards Aggregation Pathway

Abstract

Three different conjugated oligomers was synthesized such as Triphenylamine combined thiazole (TPA‐TZ), Triphenylamine combined benzothiazole (TPA‐BTZ) and triphenylamine combined benzothiadiazole (TPA‐BTDZ) by Wittig condensation route. The effect of imine groups on the acceptor side from three oligomers were analysed from spectroscopic (FT‐IR, UV‐visible, fluorescence), thermal stability and electrochemical (Cv and conductivity) studies. These oligomers exhibited positive solvatochromism with respect to different polarity of the solvents. Absorption spectra resulted π‐π* electronic transition was occurring at 330–364 nm in a solution state. The oligomers TPA‐TZ, TPA‐BTZ exhibited bluish green fluorescence emission at 465, 455 nm and TPA‐BTDZ exhibited orange colour fluorescence emission at 566 nm. The electrochemical band gaps of the oligomers were calculated around 1.3‐1.5 eV. The thermal analysis reveals that the TPA‐BTDZ has shown higher thermal stability up to 270 °C than other oligomers. The benzothiadiazole based TPA (TPA‐BTDZ) has shown low band gap and optimum electrochemical conductivity (1.53×10−5 Ω−1 cm−1) than other oligomers. By increasing the water: THF fraction, switching of different emission colour, observed different emission wavelength and the particles was aggregated which was examined from SEM images.