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 ε-Ga₂O₃ layer to the PEDOT:PSS/ε-Ga₂O₃ (PGO) hybrid heterojunction. By adopting the annealed ε-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 2.37×10⁷, 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 9.2×10¹³ Jones, an outstanding external quantum efficiency of 33.2%, and a high rejection ratio (R₂₅₀/R₄₀₀) of 5.96×10⁶ at 0 V in PGO-O₂ PD. The better photoresponse is attributed to the less V_o defect concentration in the ε-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. [ABSTRACT FROM AUTHOR]