Temperature-induced photoluminescence amplification of graphene oxide-polyaniline composite through interaction modulated charge transfer

Abstract

This report plies the effect of temperature on the interaction of GO and polyaniline at different pH through photoluminescence (PL) studies. At neutral pH, the interaction of GO-PANI is found to be highly temperature-dependent. A ground state charge transfer (CT) from the polaronic state of PANI to the GO remained at the backbone of the photophysics. The electron transfer from PANI to GO becomes more significant at a higher temperature because of the better interaction of GO with PANI moiety through π−π stacking and hydrogen bonding. The CT-induced PL amplification at elevated temperature is originating from the recombination of the spatially separated electron in the excited state of GO and hole in the PANI. The thermodynamic parameters ΔH and ΔS have been calculated associated with the electron transfer process. The positive change in the electronic entropy due to the better delocalization overcomes the entropy change due to structural orderness that drives the electron transfer process. The intensity of different PL bands remains unaffected by the temperature at lower pH due to saturated electron transfer and lower GO-PANI interaction, whereas at higher pH the CT PL band intensity decreases with an increment in temperature, explained by the increase in GO-PANI distance.