Cascading electron transfer and photophysics in a donor-π-acceptor graphene nanoconjugate
Lulu Fu, Hui Li, Yan Fang, Zihao Guan, Zhiyuan Wei, Naying Shan, Fang Liu, Yang Zhao, Mingfei Zhang, Zhipeng Huang, Mark G. Humphrey, Chi Zhang
Abstract
Electron-donating porphyrins (Por), electron-accepting phthalocyanines (Pcs), and reduced graphene oxide (RGO) were integrated into a multicomponent nanoconjugate (Por-RGO-Pc). The donor-π-acceptor nanoconjugate Por-RGO-Pc was characterized using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and ultraviolet—visible (UV—Vis) spectroscopy. Photoinduced cascading electron/charge transfer from Por to RGO and from RGO to Pc was established from fluorescence, electrochemical, and femtosecond transient absorption (fs-TA) spectroscopy studies. The increased distance between the electron donors and acceptors of the Por-RGO-Pc nanoconjugate compared to the parent materials and the intermediate RGO-Pc results in long-lived charge separation, and an enhancement in nonlinear optical (NLO) absorption (a large NLO coefficient of about 827.44 cm/GW) towards nanosecond laser irradiation at 532 nm.