Oxygen vacancies modulating self-powered photoresponse in PEDOT:PSS/ε-Ga2O3 heterojunction by trapping effect

Can the modulation effect of charge-carrier transfer be inherited from a single layer to its heterojunction structure? Certainly, the answer is yes. Herein, we experimentally verify that the photodetection performance modulation effect of oxygen vacancy (V-o) is transmitted from the epsilon-Ga2O3 layer to the PEDOT:PSS/epsilon-Ga2O3 (PGO) hybrid heterojunction. By adopting the annealed epsilon-Ga2O3 films, whose V-o concentrations are remolded by annealing ambients, the constructed PGO photodetectors (PDs) demonstrate regulable self-powered performance. As the V-o defects decrease, the photodetection properties are effectively enhanced with a high photo-to-dark current ratio of 2.37x 10(7), an excellent on/off switching ratio of 6.45 x 10(5), fast rise/decay time of 121/72 ms, a large responsivity of 67.9 mA/W, superior detectivity of 9.2x10(13) Jones, an outstanding external quantum efficiency of 33.2%, and a high rejection ratio (R-250/R-400) of 5.96 x10(6) at 0 V in PGO-O-2 PD. The better photoresponse is attributed to the less V-o defect concentration in the epsilon-Ga2O3 layer, which could favor the lower electron-trapping probability and a more efficient charge-carrier transfer. Considering the universality of V-o defects in oxide materials, the proposed regulation strategy of photoresponse will open the route of high self-powered performance for next-generation ultraviolet PDs.