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Rebecca Scheidt1 Gergely Samu2 1 Janaky Csaba2 Prashant Kamat1

1, University of Notre Dame, Notre Dame, Indiana, United States
2, University of Szed, Szed, , Hungary

TiO2 , an electron transport layer (ETL), plays an important role in delivering superior device performance of perovskite solar cells. We have now probed the TiO2/perovskite interface by anchoring CsPbBr3 nanocrystals on mesoscopic TiO2 films and elucidated the charge injection process through transient absorption spectroscopy and the processes leading to the photodegradation of CsPbBr3 nanocrystals. In addition, we have also probed the influence of TiO2 on the charge carrier recombination process by conducting spectroelectrochemical experiments with FTO/TiO2/CsPbBr3 films at different applied electrochemical bias. A decrease in the charge carrier lifetimes of CsPbBr3 was observed as we increase the potential from -0.6 V to + 0.6 V vs. Ag/AgCl. Interestingly, the charge carrier lifetime increased upon reversing the applied bias, thus indicating the reversibility of the photoresponse to charging effects. The indirect influence of electron accumulation (or depletion) in TiO2 layer on the charge recombination rate is likely to play an important role dictating the overall performance of perovskite solar cells.

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