Monolayer Cesium Lead Bromine Chloride Nanocrystal Self-Powered Photodetectors

We introduce a route to fabricate monolayer cesium lead bromine chloride (CLBC) nanocrystal films for self-powered perovskite photodetectors (PDs). Combining spin-coating method and two-step halide exchange process, a uniform and dense perovskite monolayer nanocrystal film is achieved and the PD with fluorine-doped tin oxide (FTO)/SnO ₂ /CLBC/carbon structure is fabricated. By tailoring the composition of perovskites, the optimal device performance is achieved for the CsPbBr _0.75 Cl _2.25 PD. Finally, our PD exhibits good self-powered optoelectronic properties in the near-ultraviolet region including an on-off ratio of 10 ⁶ , a responsivity (R) of 0.23 A/W, an open-circuit voltage of up to 1.6 V, and a detectivity of $1.38\times10$ ¹² Jones. Besides, the devices are also quite photostable. These results open a new avenue for fabricating high-performance perovskite PD.