Aggregation induced emission (AIE) based donor–π–acceptor fluorophores: an approach to fabricate acidochromic sensors and white light emitting diodes

Abstract

This work reports the design and synthesis of two donor–π–acceptor based fluorescent probes (TPASCNPy and TPESCNPy). Both these probes inherit intramolecular charge transfer (ICT) features triggered by the D–π–A interaction and AIE characteristics due to the presence of a triphenylamine (TPA) and tetraphenylethylene (TPE) moiety. Taking advantage of the pH-sensitive reversible fluorescence emission features (swapping between the non-emissive state at pH < 4 to highly red emissive at pH > 4 for TPASCNPy and red emissive at pH < 4 to highly yellow emissive at pH > 4 for TPESCNPy) allows the use of both these fluorophores to detect volatile organic compounds with high acidity and as fluorescent pH sensors in both solution and solid states. The sensing mechanism is analyzed using UV-vis, fluorescence, and ¹H NMR spectroscopic analysis. Additionally, both molecules are also used for the fabrication of white LEDs due to their broad emission in the visible region. The hybrid white LED fabricated by conjugating these probes with a blue LED chip, is found to show superior white light emission characteristics (CCT (4121 K), LER (270 lm W⁻¹) CRI (75), CIE (x = 0.36, y = 0.34)) depicting its potential for lighting applications.