p–n junction induced electron injection type transparent photosensitive film of Cu₂O/carbon quantum dots/ZnO

Abstract

An electron injection type transparent photosensitive CuO/carbon quantum dot (C QD)/ZnO p-n junction film was prepared by a simple route in which, successively, the ZnO film was prepared by a sputtering process, the C QDs and CuO were prepared by hydrothermal synthetic and chemical methods, then the C QDs and CuO were introduced onto the surface of the ZnO film. The results indicated that the C QDs and CuO were well combined with the ZnO film. The transparency and photosensitivity of this film were investigated, and exhibited an obvious photosensitive enhancement compared with those of the unmodified film. Through analysis, this enhancement of the photoconductivity could be attributed to the remarkable CuO/ZnO p-n junction and C QDs with unique up-converted photoluminescence.

Transparent p-Cu0.66Cr1.33O2/n-ZnO heterojunction prepared in a five-step scalable process

“…Nonetheless the high cost of indium and its toxicity reclaim alternative solutions and at the moment the most promising one seems to be the zinc oxide (ZnO), a direct bandgap semiconductor with suitable electrical and optical properties (Eg = 3.4 eV [7], transmittance above 80% in the visible region [8][9][10]), high chemical resistance and low fabrication cost compared with ITO. ZnO, in its undoped or doped forms (Al:ZnO or Ga:ZnO) starts already to find their way into applications [11][12][13][14].…”

Built-in electric field promotes photoexcitation separation and depletion of most carriers in TiO2:C UV detectors

“…270 nm. This proves that C QDs is an indirect band-gap semiconductor [34,35]. The former absorption edge of C QDs corresponds to the indirect bandgap optical absorption and the latter results from the direct band-gap absorption.…”