Enhanced photoactivity and conductivity in transparent TiO2 nanocrystals/graphene hybrid anodes

An optically transparent and UV-light active anode, characterized by high (photo) conductivity, charge mobility and exciton lifetime, based on graphene, grown by CVD, decorated with colloidal TiO2 nanocrystals (NCs), has been fabricated, by a direct and facile solution-based procedure. TiO2 NCs anchor onto graphene by means of p-p stacking interactions occurring between the pyrene-1-butyric acid (PBA) surface coating ligand and the 2-D platform and assemble in a highly interconnected multilayered layout, by means of interligand pi-pi forces, retaining composition and geometry, along with the graphene structure. Remarkably, the PBA-coated TiO2 NCs on the graphene increase its electrical conductivity, electroactivity, and capacitive behavior, as well as photoelectrical response under UV-light, resulting in a 50% enhanced photoelectroactivity and a long exciton recombination lifetime. The photoanodes can be integrated into solar cells as optically transparent electrodes, in photodetectors, FETs and (bio)sensors.