A synergistic ZnO/FAPbBr3 nanocrystal n–n heterojunction for low-bias, fast, broadband photodetection and memristive applications

Abstract

Heterojunctions formed between metal halide perovskites and wide-bandgap oxides have emerged as a powerful platform for broadband photodetection, leveraging their complementary optoelectronic properties and tunable interfacial dynamics. In this study, we demonstrate the synergistic integration of an n–n type-II ZnO/FAPbBr₃ nanocrystal (NC) heterojunction, enabling efficient broadband photodetection at low bias voltages with rapid response characteristics. Under white light illumination (48.27 mW cm⁻²), the device achieves peak photoresponse at a 1 V bias, exhibiting an impressive on/off current ratio of ∼1.44 × 10⁴, a responsivity of 0.668 A W⁻¹, and a specific detectivity of 7.78 × 10¹¹ Jones. The engineered interface facilitates effective charge separation and transport, while the spectral overlap between ZnO and FAPbBr₃ NCs extends the photoresponse across the visible and near-UV regions. Notably, the device demonstrates a fast temporal response with rise and fall times of 80 μs and 90 μs, respectively—making it suitable for high-speed imaging applications. Additionally, cyclic voltage sweeps reveal an analog switching behavior, indicative of gradual conductance modulation. This memristive-like response suggests potential utility in neuromorphic systems, where such analog switching can emulate synaptic functionalities. Overall, the ZnO/FAPbBr₃ NC heterojunction exemplifies a multifunctional architecture, combining high-performance photodetection with prospects for artificial synapse implementation in next-generation neuromorphic electronics.