Enhanced Cs3Cu2I5/Si heterojunction photodetectors based on pulsed laser deposited Cs3Cu2I5 films on micron-scale patterned substrates

Lead-free all-inorganic metal halide perovskites have garnered significant interest due to their exceptional optical and electrical applications. In addition, patterned perovskite films could enhance the performance of the perovskite-based devices. In this work, the microscale cylinder arrays with various diameters were fabricated on Si(100) substrates, and the Cs3Cu2I5 thin films were deposited on the microarrays by pulsed laser deposition. Then, the Cs3Cu2I5/Si heterojunction photodetectors were constructed with Ni/Au and Au electrodes. The reflectivity and photoluminescence spectra demonstrated that the microarrays can reduce surface reflectivity and increase light absorption in heterojunction devices. In addition, the microscale arrays improved the Cs3Cu2I5/Si heterojunction photodetectors performance. As the array diameter decreased, the peak responsivity and specific detectivity of the photodetectors increased significantly, reaching 124.4 mA/W for a 4 μm array. In addition, the photodetectors on microscale arrays demonstrated improved stability with a slightly reduced response speed. The results highlight the potential for microscale structures in enhancing optoelectronic devices.