Photovoltaic broadband photodetectors based on CH₃NH₃PbI₃ thin films grown on silicon nanoporous pillar array

The research of broadband photodetectors has been attracting extensive attention because of their great importance and application potentials in numerous fields. In this study, we proposed a perovskite-based photovoltaic broadband photodetector using silicon nanoporous pillar array (Si-NPA) as the hole-transport layer as well as the growth template. By optimizing the conditions of solvent vapors annealing approach, the conformal growth of high-quality CH₃NH₃PbI₃ (MAPbI₃) thin films was achieved with a high material integrity, thus enabling a rapid and efficient carrier transport at the MAPbI₃/Si-NPA interface. The photoresponse analysis reveals that the devices exhibit a high light sensitivity from the deep ultraviolet to the near-infrared region and a pronounced photovoltaic behavior. Typically, a high on/off ratio of 0.82 × 10⁵, a photoresponsivity of 8.13 mA/W, a specific detectivity of 0.974 × 10¹³ Jones, and fast response speeds of 253.3/230.4 μs were achieved at zero bias under light illumination of 780 nm. Because of the using of air-stable inorganic carrier-transport layers (Si-NPA, ZnO), and the coaxial core/shell heterojunction architecture for a full protection of vulnerable MAPbI₃ active layer from exposure to air ambient, the photodetectors without encapsulation can operate with an excellent stability and repeatability in a wide frequency range over 5000 Hz and continuous light switching (1200 cycles). Even after one-month storage in air ambient, the devices can operate properly with only 8% photocurrent decay. The results obtained provide an effective strategy for the design and development of high-performance broadband photodetectors by combining the advantages of perovskites and functional Si-NPA template.