Tailoring the optical properties of ZnO thin film by Citrus limon doped Polypyrrole

In this paper we demonstrate an approach to synthesize composite thin film comprising of polypyrrole (PPy) and zinc oxide (ZnO) by Solution casting method to meet the demand of LEDs. Commercial citric acid doped PPy (D1-PPy) and Citrus limon doped PPy (D2-PPy) has been synthesized via oxidative polymerization method. The effects of dopants on the physicochemical properties were investigated in detail. Interestingly, D2-PPy revealed lower bandgap when compared to D1-PPy due to the presence of polyphenols and terpenes in citrus limon. Due to the synergistic effect of ZnO and PPy, the absorption spectra extended to the visible region of the solar spectrum. The Room Temperature photoluminescence (RTPL) measurements reveal the enhancement of UV emission for D2-PPy/ZnO/PVA thin film which might be due to electronic passivation effect. The presence of –OH group in both the PVA and citric acid blocks the oxygen vacancy in ZnO, and exhibits enhanced near band edge emission. Thus, opens up the possibility of the D2-PPy/ZnO/PVA as a suitable candidate for UV based LEDs.