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A practical method for organic–inorganic hybrid heterojunction photodetector by spin-coating the cobalt phthalocyanine (CoPc) solution onto the β-gallium oxide (β-Ga2O3) film is available to realize the sensitive detection of ultraviolet light signals. We have carefully measured and calculated the optoelectronic performance of the prepared device. The device demonstrates excellent rectification characteristics under different light intensities, and the rectification ratio reaches 144.96 under 900 μW/cm2 at ±5 V. Benefiting from the construction of CoPc/Ga2O3 heterojunction, the device shows an extremely low dark current of 5.73 fA, a high detectivity of 1.92 × 1017 Jones, a responsivity of 18.4 mA/W, and a high light-to-dark current ratio of 3.76 × 106. In addition, the intrinsic physical mechanism of the device is investigated through the energy band diagram under different conditions. The device is equipped with the possibility to work under self-powered mode and has good stability in the air environment. [ABSTRACT FROM AUTHOR]

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-Ga2O3 layer to the PEDOT:PSS/ε-Ga2O3 (PGO) hybrid heterojunction. By adopting the annealed ε-Ga2O3 films, whose Vo concentrations are remolded by annealing ambients, the constructed PGO photodetectors (PDs) demonstrate regulable self-powered performance. As the Vo 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 Vo 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 Vo 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]

• A β-Ga 2 O 3 /CuBiI 4 heterojunction deep-ultraviolet photodetector was constructed. • The fabricated device exhibited responsivity of 20.68 A/W and detectivity of 3.72 × 1015 Jones. • The detector could display self-powered operation. Herein, a β-Ga 2 O 3 /CuBiI 4 heterojunction deep-ultraviolet (DUV) photodetector was constructed based on metal-organic chemical vapor deposition grown β-Ga 2 O 3 film and spin-coated CuBiI 4 film. In which, we prepared the pure and well-crystallized CuBiI 4 film from environment-friendly materials under optimized experimental conditions. The fabricated device exhibited a large responsivity of 20.68 A/W, a high specific detectivity of 3.72 × 1015 Jones, a high photo-to-dark current ratio of 5.62 × 106, a low dark current of 0.385 pA, and an ultrahigh UV/visible rejection ratio (R 250 nm / R 400 nm) of 1.14 × 104 under 254 nm UV light illumination at 5 V. In all, the device can sensitively monitor a wide range of UV light (254 nm) intensities from 0.1 to 2000 μW/cm2. Moreover, the potential of the device operating under self-powered mode has been verified, and the intrinsic physical mechanism of the heterojunction photodetector was analyzed via energy-band alignment. Overall, this work would present a promising route to realize high-performance and cost-effective DUV photodetector. [ABSTRACT FROM AUTHOR]

• Solution processed VOx films obtain changeable conductivities in 2 orders of magnitude range. • Regulable conductivity of VO x enables effective hole-transport engineering in VO x /Ga 2 O 3 heterojunction. • Optimized VO x /Ga 2 O 3 photodetector demonstrates enhanced self-powered ultraviolet photodetection performance. The self-powered photodetection performance of the VO x /Ga 2 O 3 heterojunction photodetector could be effectively and positively regulated via the VO x hole transport layer by charge-carrier engineering, inducing the record PDCR of 1.08 × 108 and superhigh on/off ratio of 1.23 × 106. [Display omitted] As the carrier behavior is crucial to the photoelectric conversion process, the charge-carrier engineering could provide feasible strategy for high-performance photodetector (PD). Herein, self-powered ultraviolet PDs were constructed on VO x /Ga 2 O 3 (VGO) heterojunctions by adopting the solution processed VO x films as hole transport layer (HTL). Treated with different annealing ambients, the HTL demonstrated changeable conductivities due to the regulated crystallinities, phase structures and chemical valences, which further exerted influences on the VGO PDs inducing controllable photodetection properties. With effective hole transportation, low valence band barrier and large built-in field, the modulated VGO PDs achieved enhanced self-powered photodetection performance with photo-to-dark current ratio of 1.08 × 108, on/off ratio of 1.23 × 106, rejection ration (R 245 / R 400) of 3.12 × 104, responsivity of 28.9 mA/W and detectivity of 1.13 × 1014 Jones as well as rise/decay time of 57/74 ms. In consideration of the carrier-transport problems are commonly ubiquitous and particularly vital, our proposed HTL engineering method could open the high-performance route for self-powered ultraviolet PDs. [ABSTRACT FROM AUTHOR]