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

Abstract

Abstract Solar‐blind ultraviolet (UV) photodetectors based on p‐organic/n‐Ga 2 O 3 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 Ga 2 O 3 (a‐Ga 2 O 3 ) 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‐Ga 2 O 3 ‐based photodetector is decreased to 0.48 pA. Meanwhile, the photoresponse parameters of the a‐Ga 2 O 3 ‐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 × 10 16 Jones and 9.1 × 10 4 % 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‐Ga 2 O 3 type‐II heterojunction, the PCDTBT/Ga 2 O 3 multifunctional photodetector shows self‐powered behavior. The responsivity of p‐PCDTBT/n‐Ga 2 O 3 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 Ga 2 O 3 heterojunction‐based photodetectors. image