Ultrahigh EQE (15%) Solar‐Blind UV Photovoltaic Detector with Organic–Inorganic Heterojunction via Dual Built‐In Fields Enhanced Photogenerated Carrier Separation Efficiency Mechanism

A new strategy of constructing an additional heterojunction on the surface of epitaxially grown Ga 2 O 3 film with a distorted lattice is proposed to solve the problem of low external quantum efficiency (EQE) in traditional Ga 2 O 3 heterojunction photovoltaic devices. Experimentally, an organic–inorganic hybrid poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate/Ga 2 O 3 /p‐type Si solar‐blind ultraviolet (SBUV) photovoltaic detector is constructed to achieve an ultrahigh EQE of ≈15% at 0 V bias, which is 1–2 orders of magnitude higher than that of the Ga 2 O 3 photovoltaic devices reported previously. Here, an enhanced mechanism of photogenerated carrier separation efficiency induced by dual built‐in fields is proposed to explain the high EQE of Ga 2 O 3 SBUV photovoltaic devices. In addition, the organic–inorganic hybrid detector displays a high SBUV–visible rejection ratio (R 255 nm /R 405 nm of ≈450) and fast response speed (rise time of 60 ms and decay time of 88 ms). All these results indicate that the strategy proposed could provide reference for the fabrication of high‐performance Ga 2 O 3 SBUV photovoltaic detectors.