Stability comparison of perovskite solar cells based on zinc oxide and titania on polymer substrates

Device scale-up and long-term stability constitute two major hurdles that the emerging perovskite solar technology will have to overcome before commercialization. Here, a comparative study was performed between ZnO and TiO2 electron-selective layers, two materials that allow the low-temperature processing of perovskite solar cells on polymer substrates. Although the use of TiO2 is well established on glass substrates, ZnO was chosen because it can be readily printed at low temperature and offers the potential for the large-scale roll-to-roll manufacturing of flexible photovoltaics at a low cost. However, a rapid degradation of CH3NH3PbI3 was observed if it was deposited on ZnO, therefore, the influence of the perovskite film preparation conditions on its morphology and degradation kinetics was investigated. This study showed that CH3NH3PbI3 could withstand a higher temperature on TiO2 than ZnO and that TiO2-based perovskite devices were more stable than their ZnO analogues