SiW₉Co₃ @rGO composite-doping improved the crystallization and stability of a perovskite film for efficient photodetection

The crystalline quality of perovskite films is a key factor that affects the performance of perovskite photovoltaic devices. Polyoxometalates can better match the energy levels of each layer in the devices through their own suitable energy level and band gap, and the good light absorption of POMs can also increase the mobility of photogenerated carriers in the devices. Moreover, POMs with Keggin-type structures can also improve the crystalline quality of perovskite films by eliminating defect sites, which can lead to better crystallization of perovskites with larger grains. In this study, we optimized the crystalline quality of a perovskite layer using the SiW9Co3@rGO composite prepared using POMs and graphene derivatives. XRD and SEM tests show that the crystallization degree of the perovskite layer was improved, the average grain size of which can reach up to 1222.92 nm, which is nearly four times higher than that of a blank perovskite. The photoresponse current of a SiW9Co3@rGO-doped photodetector can reach to 43.94 mu A, which is about 226% higher than that of an undoped device. At the same time, the addition of the composite can improve the stability of photodetectors because of the special network structure of graphene. Photodetectors doped with SiW9Co3@rGO can still maintain more than 90% of their high performance for a month. This study proves that POM-based composites have good application prospects in the field of photovoltaic devices.