Oxygen vacancies modulating self-powered photoresponse in PEDOT:PSS/ε-Ga2O3heterojunction 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 (Vo) is transmitted from the ε-Ga2O3layer to the PEDOT:PSS/ε-Ga2O3(PGO) hybrid heterojunction. By adopting the annealed ε-Ga2O3films, whose Voconcentrations are remolded by annealing ambients, the constructed PGO photodetectors (PDs) demonstrate regulable self-powered performance. As the Vodefects decrease, the photodetection properties are effectively enhanced with a high photo-to-dark current ratio of 2.37×107, an excellent on/off switching ratio of 6.45×105, fast rise/decay time of 121/72 ms, a large responsivity of 67.9 mA/W, superior detectivity of 9.2×1013Jones, an outstanding external quantum efficiency of 33.2%, and a high rejection ratio (R250/R400) of 5.96×106at 0 V in PGO-O2PD. The better photoresponse is attributed to the less Vodefect concentration in the ε-Ga2O3layer, which could favor the lower electron-trapping probability and a more efficient charge-carrier transfer. Considering the universality of Vodefects in oxide materials, the proposed regulation strategy of photoresponse will open the route of high self-powered performance for next-generation ultraviolet PDs.