Blue photoluminescence from chemically derived graphene oxide

Fluorescent organic compounds are of significant importance to the development of low-cost opto-electronic devices. Blue fluorescence from aromatic or olefinic molecules and their derivatives is particularly important for display and lighting applications. Thin film deposition of low-molecular-weight fluorescent organic compounds typically requires costly vacuum evaporation systems. On the other hand, solution-processable polymeric counterparts generally luminesce at longer wavelengths due to larger delocalization in the chain. Blue light emission from solution-processed materials is therefore of unique technological significance. Here we report near-UV to blue photoluminescence (PL) from solution-processed graphene oxide (GO). The characteristics of the PL and its dependence on the reduction of GO indicates that it originates from the recombination of electron-hole (e-h) pairs localized within small sp2 carbon clusters embedded within an sp3 matrix. These results suggest that a sheet of graphene provides a parent structure on which fluorescent components can be chemically engineered without losing the macroscopic structural integrity. Our findings offer a unique route towards solution-processable opto-electronics devices with graphene.