Carbon Nanotube Network-Engineered Interfacial Charge Transport in ZnO/Perovskite Photodetectors for Wavelength-Dependent Signal Encoding

Abstract

Perovskite/ZnO heterojunctions are promising for broadband photodetection, but limited charge extraction at metal contacts can prolong carrier residence and promote slow trap-mediated responses. Here, a nanoscale network of semiconducting single-walled carbon nanotubes (s-SWCNTs) was inserted at the Au/ZnO interface to provide an additional charge-extraction pathway. Relative to the control device, the modified device exhibited reduced persistent photoconductivity and more stable switching under 365 and 550 nm illumination. At a bias of 50 μV, the corresponding rise/decay times decreased to 78/66 ms at 365 nm and 83/63 ms at 550 nm, improving by more than one order of magnitude. Replicated Kelvin probe force microscopy and ultraviolet photoelectron spectroscopy measurements revealed architecture-associated electrostatic and surface electronic-structure shifts, supporting a proposed model of contact-mediated charge extraction. In separate spectral measurements at 10 V, the peak responsivity reached 10.06 A W−1 at 290 nm, with an external quantum efficiency of approximately 4.3 × 103%; responsivities at 365 and 550 nm were 6.44 and 6.15 A W−1, respectively. Measured current responses were subsequently used for proof-of-concept text encoding and offline exclusive-OR image mapping. These results demonstrate how a one-dimensional carbon nanotube network can regulate interfacial charge extraction and switching dynamics in hybrid broadband photodetectors.