Propelling efficiency and stability of planar perovskite solar cells via Al2O3 interface modification to compact TiO2 layer

An effective and facile surface optimization method is conducted by spin-coating the solution containing Al(NO3)3 upon compact TiO2 (c-TiO2) electrode for enlarging the performance of planar perovskite solar cells (p-PSCs). Meanwhile, the influence of Al(NO3)3 solution concentration on efficiency performance of p-PSCs is also carefully investigated. The study results highlight that a discrete Al2O3 film can be formed on c-TiO2 electrode to passivate superficial oxygen vacancies defects and create a pleasurable surface topography, alone with high optical transparency. As a consequence, the champion device based on the modified c-TiO2 (Al-TiO2) via spinning 0.7 wt% Al(NO3)3 solution drastically yields an enhanced power conversion efficiency of 14.75% as well as enjoys superior device stability compared to its counterpart based on bare c-TiO2. Through a further analysis, the fact that Al-TiO2 can effectively augment the charge collection and abate charge recombination efficiency by the suppression of oxygen vacancy defects at Al-TiO2/CH3NH3PbI3-xClx interface than that of bare c-TiO2 without modification is unveiled. Those findings provide an insight into the correlation between p-PSCs performance and the microscopic characteristics of c-TiO2, and put forward an effective measure to further promote the performance of p-PSCs for their record efficiency.