The role of TiO2 as an electron transport layer (ETL) that captures electrons from excited CsPbBr3 seems to play an important role in delivering superior device performance. However, its role in perovskite solar cell is yet to be understood fully. By anchoring CsPbBr3 nanocrystals onto mesoscopic TiO2 film, we have probed the charge injection from excited perovskite into mesoscopic TiO2 and other semiconductor oxides. The electron transfer rate constant in all these case was found to be >1011s-1. When subjected to steady state irradiation with visible light in air, the injected electrons are scavenged away from the TiO2 , thus inducing oxidation of CsPbBr3 nanocrystals. No such degradation is seen when CsPbBr3 nanocrystals are coated on an inert support such as ZrO2. We have also probed the charge recombination process in CsPbBr3 deposited on FTO/TiO2 films at different applied electrochemical bias and investigate the influence of electron charging effect in TiO2 layer. Steady state and luminescence measurements that elucidate the role of TiO2 in the solar cell operation will be discussed.