Heteropoly Blue Modified SnO2 for Highly Efficient Perovskite-Based Photodetectors

Due to the higher electrical conductivity, SnO₂ becomes a promising material for electron transport layers (ETLs). However, the mismatched energy level and surface defects lead to unsatisfactory contact between the perovskite film and SnO₂ layer, which limits its further application. Herein, heteropoly blue (HPB) r-PMo_12–xV_x (x = 0, 1, 2) is chosen to modify the interface contact between the perovskite layer and the SnO₂ layer. The energy level of HPB-modified SnO₂ increases from −4.49 to −4.09 eV, which is more suitable with the perovskite layer, thus improving the electron transport. In addition, the introduction of HPBs reduces the oxygen defects on the surface of SnO₂, while metal–oxygen bonding in the HPBs can improve the quality of the perovskite film by passivation. As a result, the photocurrent of the photodetector increases from 22.4 to 81.7 μA, an enhancement of about 3.6 times. In particular, the HPB-modified photodetector can still maintain 90% of the initial performance after 700 h and the stability is significantly improved, providing a good idea for efficient and stable perovskite photodetectors.