Large-Area Heterojunction Photodetectors Based on Nanometer-Thick CH₃NH₃PbI₃ Films Modified with Poly(methyl methacrylate) Nanofilms

The metal halide organic–inorganic perovskite material provides a broad prospect for the development of high-performance photoelectric detectors due to its extraordinary optical and electrical properties. In this work, a nanometer-thick CH3NH3(MA)PbI3 heterojunction photodetector (PD) with an ultralarge scale of 1.0 cm × 1.0 cm is prepared and a facile approach is proposed to enhance the performance of the heterojunction PDs by introducing a poly(methyl methacrylate) (PMMA) nanolayer to modify the MAPbI3 film. The heterojunction PD achieves a broadband photoresponse from 300 to 800 nm and can work well without any external bias. Moreover, after the modification with a suitable concentration of the nanometer-thick PMMA, the crystal quality of the MAPbI3 layer, as well as the performance of the heterojunction PD, is greatly enhanced, and the photosensitivity, responsivity, specific detectivity, and response times are as high as 2.09 × 104, 0.46 A/W, 3.18 × 1010 Jones, and 0.21/0.12 s, respectively. In addition, the ambient and thermal stabilities of the MAPbI3 heterojunction PD are largely improved, which can also be attributed to the protection and passivation of the PMMA nanolayer. This work definitely demonstrates a cost-effective method for designing large-scale, stable, high-performance, self-powered photodetectors and also opens great opportunities for developing low-cost and broadband perovskite-based photoelectric devices.