ABSTRACT
Ga2O3 is a wide-bandgap semiconductor that has shown great potential for application in solar-blind ultraviolet (UV) photodetectors. However, the responsivity and detectivity of Ga2O3-based self-driven solar-blind UV photodetectors are insufficient for practical applications at present because of the limited separation of photogenerated carriers in the devices. In this work, Hf0.5Zr0.5O2/ß-Ga2O3 heterojunction-based self-driven solar-blind UV photodetectors are constructed by combining ferroelectric Hf0.5Zr0.5O2 (HfZrO2) material with Ga2O3, taking advantage of the ultrawide bandgap of HfZrO2 and the favorable II-type energy band configuration between both. Upon optimization, a HfZrO2/ß-Ga2O3 heterojunction-based UV photodetector with a HfZrO2 layer thickness of 10 nm is shown to provide remarkable responsivity (R = (14.64 ± 0.3) mA/W) and detectivity (D* = (1.58 ± 0.03) × 1012 Jones), which are much superior to those of a single Ga2O3-based device toward 240 nm light illumination. Further, the device performance is adjustable with varying poling states of HfZrO2 and shows substantial enhancement in the upward poling state, benefiting from the constructive coupling of the ferroelectric depolarization electric field in HfZrO2 and the built-in electric field at the HfZrO2/ß-Ga2O3 interface. Under illumination of weak light of 0.19 µW/cm2, the upward poled device shows significantly enhanced R (52.6 mA/W) and D* (5.7 × 1012 Jones) values. The performance of our device surpasses those of most previously reported Ga2O3-based self-driven photodetectors, indicating its great potential in practical applications for sensitive solar-blind UV detection.
ABSTRACT
Zinc-based electrochemistry attracts significant attention for practical energy storage owing to its uniqueness in terms of low cost and high safety. In this work, we propose a 2.0-V high-voltage Zn-MnO2 battery with core@shell Co3O4@MnO2 on carbon cloth as a cathode, an optimized aqueous ZnSO4 electrolyte with Mn2+ additive, and a Zn metal anode. Benefitting from the architecture engineering of growing Co3O4 nanorods on carbon cloth and subsequently deposited MnO2 on Co3O4 with a two-step hydrothermal method, the binder-free zinc-ion battery delivers a high power of 2384.7 W kg-1, a high capacity of 245.6 mAh g-1 at 0.5 A g-1, and a high energy density of 212.8 Wh kg-1. It is found that the Mn2+ cations are in situ converted to Mn3O4 during electrochemical operations followed by a phase transition into electroactive MnO2 in our battery system. The charge-storage mechanism of the MnO2-based cathode is Zn2+/Zn and H+ insertion/extraction. This work shines light on designing multivalent cation-based battery devices with high output voltage, safety, and remarkable electrochemical performances.
