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CuAlO2 was synthesized by a hydrothermal method, in which the Cu–O dimers were incorporated by simply altering the ratio of the reactants and the temperature. The incorporation process increases the grain size in CuAlO2, and modulates the work function and binding energies for CuAlO2 due to the partial substitution of Cu+ 3d10 with Cu2+ 3d9 orbitals in the valence band maximum by alloying non-isovalent Cu–O with a CuAlO2 host. Based on the ZnO nanorod arrays (NRs) ultraviolet photodetector, CuAlO2/Cu–O fabricated by the low-cost drop-coating method was used as the p-type hole transport layer. The incorporation of the Cu–O clusters into CuAlO2 lattice to enhance the conductivity of CuAlO2 is an effective way for improving ZnO NRs/CuAlO2 device performance. The photodetectors exhibit significant diode behavior, with a rectification ratio approaching 30 at ±1 V, and a dark saturation current density 0.81 mA cm−2. The responsivity of the ZnO-NRs-based UV photodetector increases from 13.2 to 91.3 mA/W at 0 V bias, with an increase in the detectivity from 2.35 × 1010 to 1.71 × 1011 Jones. Furthermore, the ZnO NRs/[CuAlO2/Cu–O] photodetector exhibits a maximum responsivity of 5002 mA/W at 1.5 V bias under 375 nm UV illumination. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate a new heterojunction ultraviolet (UV) photodetector in a superstrate configuration, i.e. glass/FTO/ZnO NRs/rGO/Au, constructed via the dip-coated method to form reduced graphene oxide (rGO) layer on the surface of ZnO nanorod arrays (NRs). The rGO compensates for surface oxygen vacancies by the oxygen-containing groups and improves the crystal properties of ZnO NRs after annealing. Furthermore, the carrier mobility and work function are effectively increased after Au doping. Under UV irradiation, the electron–hole pairs generated by ZnO NRs are separated with bias voltage, and the electrons and holes are collected via fluorine-doped tin dioxide (FTO) and rGO/Au, respectively. The rGO acts as a hole transport layer, which reduces the recombination of carriers and increases the current density, giving rise to a higher responsivity (67.48 A W−1 at −1.5 V bias) than pure ZnO NRs photodetectors. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) photodetectors with high responsivity, fast response speed and better stability have attracted much attention. In this work, heterojunctions based on ZnO nanorods (ZnO NRs)/CuI were successfully prepared by combinational chemical hydrothermal and drop-coating methods, which could be employed as self-powered and external powered UV photodetectors. The ZnO NRs were homogeneous covered and coated by CuI layer. The introduction of CuI enhanced the UV emission and weakened the defect emission of ZnO. The space-limited domain annealing was adopted to post-treat the CuI layer, which is useful to prevent the significant loss of iodine in the thin films. The UV photodetector based on ZnO NRs/CuI shows the responsivities of 86.84 mA W−1 at 0 V bias voltage and 4.41 × 104 mA W−1 at −2.5 V bias voltage under 380 nm irradiation. The rise and decay time for the devices are both 110 ms. The incorporation of CuI benefits the separation of photon-generated carriers. The facile, practical and low-cost synthesis makes ZnO NRs/CuI heterojunction a potential candidate for vertical UV-A photodetectors with high responsivity. • The ZnO NRs/CuI heterojunction was fabricated by the facile, low-temperature, and low-cost methods. • Space-limited domain annealing was used to reduce the significant loss of iodine in the thermal treated process of CuI. • Self-powered ZnO/CuI heterojunction exhibits a responsivity of 86.84 mA/W under 380 nm irradiation. • External powered ZnO/CuI heterojunction exhibits a responsivity of 4.41×104 mA/W at -2.5 V bias under 380 nm irradiation. [ABSTRACT FROM AUTHOR]