Ethylenediamine-modified graphene oxide covalently functionalized with a tetracarboxylic Zn(ii) phthalocyanine hybrid for enhanced nonlinear optical properties

Abstract

Tetracarboxylic Zn(II) phthalocyanine–amino functionalized graphene oxide (ZnPcC₄–NGO) hybrid materials have been prepared by a covalent functionalization method. The characterizations indicate that the amino-functionalization of GO has an important influence on the structure and photophysical properties of the ZnPcC₄–NGO hybrid. The ZnPcC₄–NGO hybrid exhibits enhanced photo-induced electron transfer or energy transfer (PET/ET), compared to the ZnPcC₄ covalent functionalized GO (ZnPcC₄–GO), owing to the presence of the extended sp² carbon configurations, along with the partial reduction of the NGO nanosheets and the introduction of electron-donating ethylenediamine. The nonlinear optical (NLO) properties of the hybrids were investigated using the Z-scan technique at 532 nm with 4 ns laser pulses. The results show that the efficient covalent functionalization and partial reduction of NGO cause the ZnPcC₄–NGO hybrid to possess evidently larger NLO properties than the individual NGO, ZnPcC₄ and the ZnPcC₄–GO hybrid. The enhanced NLO performance can be attributed to the increased excited state absorption from the extended sp² carbon configurations of the NGO moiety, reverse saturable absorption arising from ZnPcC₄ moiety, and the contribution of the efficient PET/ET process between the ZnPcC₄ and NGO moieties in the hybrid.