Photoresponse improvement of a MAPbI3 p-i-n heterojunction photodetector by modifying with a PCBM layer and optimizing ZnO layer thickness

In this manuscript, a series of Spiro-OMeTAD/CH3NH3(MA)PbI3/ZnO p-i-n heterojunction PDs are prepared and the photoresponses are well studied by modifying the MAPbI3/ZnO interface with a PCBM layer and modulating the ZnO film thickness ranging from 20 to 95 nm. The PD shows an excellent self-powered capability due to the suitable band alignment. After introducing the PCBM layer, both the photoresponse and stability are greatly improved, which can be attributed to its suitable band level and outstanding properties of contact passivation and interfacial modification. Besides, it is indicated that the photoresponse is strongly dependent on the thickness of the ZnO layer. The PD with a 65 nm-thick ZnO layer achieves the best performances in a broadband spectral range of ∼350 to ∼800 nm with the maximum responsivity (R) of 0.443 A/W and response times of 0.25/0.14 s. This work provides an essential insight for designing high-performance ZnO electron-transport layer-based perovskite heterojunction PDs.