Multifunctional solar‐blind ultraviolet photodetectors based on p‐PCDTBT/n‐Ga2O3 heterojunction with high photoresponse

Abstract Solar‐blind ultraviolet (UV) photodetectors based on p‐organic/n‐Ga2O3 hybrid heterojunctions have attracted extensive attention recently. Herein, the multifunctional solar‐blind photodetector based on p‐type poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)] (PCDTBT)/n‐type amorphous Ga2O3 (a‐Ga2O3) is fabricated and investigated, which can work in the phototransistor mode coupling with self‐powered mode. With the introduction of PCDTBT, the dark current of such the a‐Ga2O3‐based photodetector is decreased to 0.48 pA. Meanwhile, the photoresponse parameters of the a‐Ga2O3‐based photodetector in the phototransistor mode to solar‐blind UV light are further increased, that is, responsivity (R), photo‐detectivity (D*), and external quantum efficiency (EQE) enhanced to 187 A W–1, 1.3 × 1016 Jones and 9.1 × 104 % under the weak light intensity of 11 μW cm–2, respectively. Thanks to the formation of the built‐in field in the p‐PCDTBT/n‐Ga2O3 type‐II heterojunction, the PCDTBT/Ga2O3 multifunctional photodetector shows self‐powered behavior. The responsivity of p‐PCDTBT/n‐Ga2O3 multifunctional photodetector is 57.5 mA W–1 at zero bias. Such multifunctional p‐n hybrid heterojunction‐based photodetectors set the stage for realizing high‐performance amorphous Ga2O3 heterojunction‐based photodetectors.