Design Of P-type Copper Based Oxide Semiconductor Device And It’s Solar Energy Conversion

Cu-based oxide including CuO and Cu₂O is a kind of important p-type semiconductor materials.They have become the key research objects in the field of photoelectrode in photoelectrochemical cell（PEC）hydrogen production system due to low-cost,abundant resource storage and non-toxic and harmless element characteristics.However,due to its own limitations,the electrode is prone to light corrosion,and the carrier diffusion length does not match the light absorption depth,which seriously restricts its practical application in the field of new energy.In order to solve these problems,we focused on the effects of heterojunction,protective layer and surface treatment on the photocatalytic activity,and analyzed the mechanism in detail.A layer of CuO flexible nanomaterials was prepared on Cu substrate by simple calcination method,and then a composite protective layer was designed and used to modify the film,so as to obtain a stable and efficient CuO/TiO₂/La₂O₃/NiO Composite photocathode.The results show that the photocurrent density of CuO was 0.3 mA/cm².The good performance of the photoelectrode was attributed to the formation of heterojunction between TiO₂ and CuO.The high electron mobility of TiO₂ and the hole extraction ability of CuO accelerate the charge separation.While the La₂O₃ protective layer can effectively prevent the contact between the electrode and the electrolyte and improve the stability（nearly 100%photocurrent was maintained after 1200 s）.In addition,NiO played a catalytic role in the decomposition of water,and the final composite electrode showed good performance.Single crystal Cu₂O was directionally synthesized by electrodeposition on FTO glass,and a 10 nm thick Ag layer was deposited on the surface of directionally grown Cu₂O by high power pulsed magnetron sputtering（HiPIMS）.The results showed that the photocurrent density of Cu₂O electrode modified by high power pulsed magnetron sputtering（HiPIMS）was 4 mA/cm²,which was more than twice that of pure Cu₂O.Moreover,the stability of photocurrent was more than 98%after 5 hours of continuous chopping illumination.It’s found that the continuous Ag film formed a dense proton isolation layer,which effectively insulateed the contact between Cu₂O and electrolyte and improved its stability.The work function of Ag is lower than that of Cu₂O,forming a Schottky junction with Cu₂O,which greatly accelerated the transport of photogenerated electrons.Therefore,the improved Cu₂O photocathode showed significantly improved activity and stability.In order to further improve the photoelectric properties of the composite system,for the first time,the polyurethane acrylate（PUA）was applied to inhibit the deactivation of Cu₂O electrode,and finally the Ag/Cu₂O/PUA/TiO₂/Pt composite electrode was successfully prepared.The experimental results showed that a photocurrent density of-5.5 mA/cm² was finally obtained,and retained 98%photo-stability after 6 hours,and the IPCE summit reached68.3%at 415 nm.The experimental results showed that Ag sputtered on FTO substrate can improve the photon utilization,while the heterojunction formed by TiO₂ loading can accelerate the separation of photogenerated carriers.Finally,Pt particles deposited on the surface catalyzed the decomposition of water.Therefore,compared with pure Cu₂O,the catalytic activity of the composite electrode was improved by more than 250%,and the composite electrode showed higher stability.By electrochemical deposition,we successfully fabricated Cu₂O"anisotropic crystal facet unit",and creatively prepared a new structure of photovoltaic（PV）and thermoelectric（TE）power generation based on"anisotropic crystal facet unit".The{100}and{111}crystal facets in single crystal Cu₂O played the role of hole and electron enrichment respectively,the carrier separation was more efficient.Under AM 1.5G simulated sunlight,the initial conversion efficiency of"anisotropic crystal facet unit"was 2.0%.Moreover,the combination of this characteristic with other technical means（such as semiconductor coupling and co-catalyst loading）are expected to improve the efficiency of photovoltaic and thermoelectric power generation,and greatly reduce the production cost.