Development of ZnSe-based Organic-Inorganic Hybrid Ultraviolet PIN Photodetectors

We developed a ZnSe-based organic–inorganic hybrid ultraviolet PIN photodetector using a transparent PEDOT:PSS window layer and investigated coating conditions to improve the ultraviolet external quantum efficiency (EQE). While a single spin-coated film provides high transmittance, its conductivity limits stable operation at higher incident optical power. By controlling film thickness and conductivity through multi-coating and by adding isopropyl alcohol (IPA) as a diluent, we achieved both high transparency and improved conductivity. A maximum EQE of 90% in the UV region was obtained with a ~70 nm PEDOT:PSS layer (IPA 20%, 2 coatings) under 10 V reverse bias.