“…89,90 The density of oxygen vacancies (that leads to Ti 3+ electronic trap states) at the TiO 2 /PVSK interface is high and several strategies were proposed to overcome the decomposition of PVSK including (1) UV filters or downconversion strategies, 50,88,91,92 (2) TiO 2 surface passivation, 25,53,93 (3) prevention of the direct contact between TiO 2 and PVSK, 36,94 (4) doping. [95][96][97][98] In addition, several materials such as mp-Al 2 O 3 , 40,46 C 60 , 47 phenyl-C 61 -butyric acid methyl ester (PCBM), 52,93 SnO 2 , 52,57,58,61 ZnO-based ETL, 99,100 and complex oxide compounds 55,[101][102][103][104] have been proposed as alternatives for the TiO 2 ETL. The complex oxides are particularly promising because they are not affected by UV light.…”