Effect of acceptor concentration in the FRET controlled photoluminescence of PMMA-ZnO nanocomposite for the application of PLED device

Abstract

Luminescent PMMA-ZnO nanocomposites are synthesised through bulk polymerization of MMA in presence of ex-situ prepared ZnO nanoplates. Variation of ZnO concentration affects the optical properties of the composite. Introduction of ZnO in the PMMA matrix makes the composite as semiconducting in nature by creating a lower energy gap in the composite. Again Förster resonance energy transfer (FRET) between PMMA (donor) to ZnO (acceptor) enhances emission of ZnO significantly. But the enhanced emission decreases with increase in ZnO concentration, i.e. the emission intensity of PMMA-ZnO nanocomposite shows an increasing trend with decrease in the content of ZnO. The energy transfer efficiency varies from 97% to 52% when the concentration of ZnO varies from 10 wt% to 30 wt%. The Photoluminescence quantum efficiency of the composite showing highest emission is calculated and found to be 74%. Corresponding theoretically calculated electroluminescence quantum efficiency is 4% at an operating voltage of 3.1 V assuming all the injected charge carriers can generate singlet exciton if the composite showing highest emission is used as an emissive layer in PLED.