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.