Tunable Band-Selective UV-Photodetectors by 3D Self-Assembly of Heterogeneous Nanoparticle Networks

Accurate detection of ultraviolet radiation is critical to many technologies including wearable devices for skin cancer prevention, optical communication systems, and missile launch detection. Here, a nanoscale architecture is presented for band-selective UV-photodetectors, which features unique tunability and miniaturization potential. The device layout relies on the 3D integration of ultraporous layers of tailored nanoparticles. By tailoring the transmittance window between the indirect band gap of TiO₂ nanoparticles and the sharp edge of the direct band gap of ZnO, a band-selective photoresponse is achieved with tunable bandwidth to less than 30 nm and photo- to dark-current ratios of several millions at a light intensity of 86 μW cm⁻² and operation bias of 1 V. The potential of this integrated morphology is shown by fabrication of the first inherent UVA photodetector with selectivity against the edge of the UVB and visible light of nearly 60 times. This tunable architecture and nanofabrication approach are compatible with state-of-the micromachining technologies and provide a flexible solution for the engineering of wearable band-selective photodetectors.