Efficient and Stable Perovskite Photodetectors Based on Thiocyanate-Assisted Film Formation

Thiocyanate-based perovskite (SCN-PVSK) photodetectors have been fabricated by introducing lead thiocyanate precursor. Incorporating SCN groups into CH3NH3PbI3 can significantly improve the device stability in air. Compared with pure CH3NH3PbI3 films, SCN-PVSK films have larger grain size and reduced trap states. The perovskite layers can be prepared by a simple solution method in air. Solvent effects on the crystallization of SCN-PVSK films have also been investigated. It is found that highly uniform, pinhole-free perovskite films can be obtained utilizing the N,N-dimethylformamide (DMF) solution of Pb(SCN)2. The SCN-PVSK based photodetectors performed a high responsivity of 12.3 A/W and a decent detectivity over 1.3 × 1013 Jones. More important, the SCN-PVSK based two-terminal photodetectors, without encapsulation, have shown great stability with 92% of the initial photocurrent being retained after storage in air (relative humidity >50%) for 10 days, whereas the value is only 10% for pure CH3NH3PbI3 devices tested under the same conditions.