Numerical Study On The Photoelectric Properties Of Several Typical Semiconductors With Different Structures

Since the beginning of the 21st century,the problem of insufficient resources and environmental pollution has become more and more serious.How to solve the difficult problems of economic and social sustainable development is imminent.Among these,energy issues have a decisive position,and are also issues that humans need to consider first.Solar energy is the new energy source with the greatest potential to become a mainstream energy source.Its reserves are extremely abundant and clean and pollution-free.It is currently the world's largest energy source that can be developed and utilized,and can meet the global human energy consumption.Since the birth of the first solar cell in 1877,people have made unremitting efforts to increase the conversion efficiency.At present,the efficiency of solar cells has exceeded 20%,and has gradually entered people's daily lives.However,solar cells developed today have advantages and disadvantages.For example,the traditional silicon-based solar cell technology is mature but expensive,and the new CZTS solar cell is environmentally friendly and inexpensive,but the synthesis is difficult and the preparation technology is not perfect.Therefore,it is still necessary to constantly strive to develop an ideal solar cell.At present,looking for new photovoltaic materials and improving the preparation technology of solar cells are two important efforts.However,the available options provided by the existing semiconductors are limited.Therefore,research on multiple compounds and new semiconductor materials can enrich the properties of the materials and increase the scope for selection.At the same time,the two-dimensional material is also a relatively new and potential development direction due to its excellent photoelectric properties.In this paper,first-principles calculation methods based on density functional theory are used to study several typical semiconductors with slow progress.These provide guidance for further understanding and improve the data of these materials,thus increasing the selection of materials.The main content of this article is as follows:?1?The electronic structure,elastic properties and optical properties of the alloy Cu₂ZnGe(Se_xS_1-x)₄were systematically analyzed.The effects of changes in the ratio of Se and S of the Group VI elements on the properties of the alloy,such as lattice constants,band gaps,and elastic constants,are discussed in detail.By comparison,we can find that our calculated values are in good agreement with other theoretical values and experimental values.This proves to some extent that our calculations are reliable.Since there is no experimental data yet,we compare the elastic constants of the alloy with the values of similar compounds Cu₂ZnSnS₄ and Cu₂ZnSnSe₄.The optical properties are described in detail with changes in Se/S.At the same time,based on the differences from some available experimental values,we modify the optical constants obtained and predict the static permittivity and refractive index of the alloy.?2?Theoretically studied the enhanced absorption of light by a cascade of monolayer MoS₂ alternately separated by high/low refractive index media layers.Due to the excitation of the guided mode resonance,the field at the interfaces of the high/low refractive index dielectric layers is strongly enhanced,and the larger tangential wave vectors allow the absorption of the p-polarized light to be enhanced.Without the aid of any other lossy material?eg plasma material?,the light absorption of the monolayer MoS₂ in the vicinity of the exciton state can be up to about 50%.When the surrounding optical characteristics are asymmetric,the absorbance will be close to 100%.This property is particularly beneficial for light-absorbing devices based on atomic-scale thickness Mo S₂,while retaining the characteristics of a single-layer MoS₂ direct bandgap.?3?The electronic structure,elastic properties and optical properties of the defect admantine compound CuGaGeSe₄ and CuGaSnSe₄ are systematically studied.Through detailed calculations and comparisons,we finally obtained three completely independent atomic arrangements,and predicted the most stable atomic arrangement of the compounds based on lattice constant and formation energy.The calculated elastic constants can be used to accurately predict the axial thermal expansion coefficient and fill in the blanks of previous data.For a more intuitive understanding,we described their optical properties,including the dielectric function,refractive index,and absorption coefficient.Our calculated zero-frequency limits?₁?0?and n?0?are very close to the corresponding theoretical values,which proves that our calculations are reliable.