The Photoelectric Properties Of Sm And Tm Doped ZnO And Their Application In Solar Cells

ZnO belongs to the typical II-VI family wide band gap oxide.The band gap is 3.37 eV at room temperature,and the exciton binding energy can reach 60 meV.The property is very stable and has excellent optical,electrical and magnetic properties.ZnO materials have broad application prospects in many aspects,such as solar cells,optoelectronic devices,semiconductor lasers,new electronic displays and photocatalysts.In the field of short wavelength semiconductor,GaN is another hot topic.In general,pure ZnO shows n type conductivity because of its intrinsic defects,but the photoelectric properties at high temperature are very unstable.Impurity doping in ZnO crystal can lead to the introduction of the defect of the component,produce the defect energy level,and improve the stability of the photoelectric properties of the material.At the same time by doping can be prepared with more excellent light transmittance and conductivity of ZnO doped ZnO materials,therefore,has become a research hotspot in the field of semiconductor materials,and rare earth elements with atomic series special shell structure,as the doping source doping ZnO material has attracted wide attention of scholars at home and abroad.Based on the CASTEP module in Materials Studio software,the band structure,density of states and optical properties of rare-earth elements(Sm and Tm)doped ZnO were calculated and analyzed by using the first principles plane wave super soft pseudopotential method.The calculated results show that the energy band of the doped system becomes thicker and denser,and the impurity energy level is present.the Fermi energy moves upward from the top of the valence band to the conduction band,the system shows stronger metallicity,the system presents n type conduction,and transforms into degenerate semiconductor.The static dielectric constant of the optical properties increased significantly,and the optical absorption properties of the doped system were significantly improved and showed obvious upconversion effect.The TCO/p-p-Si/n-ZnO:Sm(Tm)heterojunction thin film solar cell is designed.Because of the good n type conductivity of the ZnO film doped with Sm and Tm,it is very suitable to be used as the N layer in the battery PN junction.When the doped thin film is used as the TCO transparent conductive electrode of the battery,it has the following two obvious advantages: 1.improved the whole solar light in the transparent conducting electrode.The transmittance of the body reduces the loss of sunlight when passing through the electrode layer.2.transform the spectral band on the surface of the light,let the sensitive band light through and be absorbed by the base material of the battery.The other non sensitive band light is converted into the sensitive band light to be absorbed by the base material,thus the full utilization of the whole solar spectral energy is realized.The TCO transparent electrode,p layer,n layer and Ti/Ag electrode were sputter on the glass substrate by magnetron sputtering,and the thin film solar cell was prepared by the sputtering.The thin film was prepared by the Suzhou Academy of science and nanotechnology and the nanoscale Research Institute of the sun.The performance of the battery was tested and characterized,and the photoelectric conversion rate reached 6.64%.