ZnO-based Self-powered Transparent Visible Light Detector

Photodetectors are widely used in signal processing,display and other fields because of their ability to convert optical signals into electrical signals.In particular,visible light detectors are widely used in image sensing,laser communication,industrial automatic control and other fields.Among many materials,ZnO based materials are favored by photodetectors because of their rich raw materials,low cost and easy preparation.However,as a wide band gap?3.2-3.37eV?semiconductor material,ZnO is widely used as a semiconductor material.ZnO-based materials are mostly used in UV photodetectors,which greatly limit the application of ZnO-based materials.In order to expand the photoelectric response range of ZnO based material and make it applicable to visible light detection,ZnO thin films were prepared by magnetron sputtering technique,and were combined with p type Cu₂O.In order to realize the photoelectric response in the visible range,the photoelectric response is further improved by the modification of carbon quantum dots,CdS quantum dots and precious metals.The main contents and achievements are as follows:1?Preparation and photosensitivity of Cu₂O/C QD/ZnO heterojunctionAn electron injection type transparent photosensitive Cu₂O/C QD/ZnO p-n junction film was prepared by a simple route in which,successively,the ZnO filmwas prepared by a sputtering process,the C QDs and Cu₂O were prepared by hydrothermal synthetic and chemical methods,then the C QDs and Cu₂O were introduced onto the surface of the ZnO film.The results indicated that the C QDs and Cu₂O 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 Cu₂O/ZnO p-n junction and C QDs with unique up-converted photoluminescence.2?Preparation and photoelectric conversion properties of Cu₂O/Ag/ZnO heterojunctionThe Ag modified transparent Cu₂O/ZnO p-n junction films were prepared by a simple magnetron sputtering process.The transparence and photoelectric conversion of these devices were investigated,which exhibited an obvious photoelectric conversion enhancement?PCE of0.48%,10 times?than those of the unmodified heterojunction.Through analysis,the enhancement of the photoelectric conversion could be attributed to the remarkable Cu₂O/ZnO p-n junction and Ag⁰ nanoparticles with the performances of photoelectron donor and surface enhanced plasmonic absorption.3?Preparation and photoelectric response of Cu₂O/CdS QD/ZnO heterojunctionTransparent films of Cu₂O/ZnO sensitized by CdS QDs were prepared by magnetron sputtering,hydrothermal method and SILAR.The translucency and photoelectric conversion properties of the films were studied.The research shows that the sensitized heterojunction of CdS QDs has a significant improvement on the photoelectric conversion performance of visible light compared with the unmodified heterojunction,which is mainly due to the full utilization of visible light and the stepped energy of CdS QDs.The structure can effectively reduce the recombination of electrons and holes,and the ordered ZnO NAs can improve the utilization of light energy,thereby improving the photoelectric conversion performance of the film.