Studies On Fabrication And Properties Of Antimony Selenosulfide Thin Film Solar Cells

The increasing depletion of traditional fossil energy has accelerated the adjustment and transformation of the existing energy structure,so clean and low-carbon new energy has gradually become the global consensus of future energy development.Photovoltaic power generation can directly convert solar energy into electricity for human production and life use,which is one of the key research and development technologies in the field of new energy.At present,the first-generation photovoltaic devices based on crystalline silicon solar cells have become the absolute mainstream of the photovoltaic market by relying on the mature manufacturing industry chain,while the second-generation photovoltaic devices represented by copper indium gallium selenium and cadmium telluride thin film solar cells have successively occupied a certain market share in the photovoltaic industry.The great progress made by the first two generations of photovoltaic products shows the great application prospect of photovoltaic technology in the field of new energy,which encourages all countries in the world to actively participate in the exploration and research of the new generation of efficient,stable,green and low-cost solar cells.Antimony selenide（Sb₂（S,Se）₃）is a new type of inorganic semiconductor material which is composed withⅤ-Ⅵgroup elements.Due to the advantages of continuously adjustable band gap（1.1～1.7 e V）,high absorption coefficient(10⁵ cm^-1),excellent photoelectric performance,stable phase,simple structure and so on,it is considered as a potential new generation photovoltaic absorber layer material.However,the research of Sb₂（S,Se）₃ thin film solar cells started late,the material preparation mechanism is not clear,and the current device conversion efficiency is far from the theoretical limit,so it is urgent to further study in order to achieve rapid industrial application in the future.In this paper,a stable and reliable vapor transport deposition process is used as the main preparation method of Sb₂（S,Se）₃ absorber layer,the preparation and performance of Sb₂（S,Se）₃ thin film solar cells are deeply studied and discussed,which provides reference value for the development of high efficiency Sb₂（S,Se）₃ thin film solar cells.Around the topic,this research has achieved some results as following:1.A stable and efficient vapor transport deposition process was developed to prepare Sb₂（S,Se）₃ thin films.With the mixture of antimony selenide（Sb₂Se₃）and antimony sulfide（Sb₂S₃）powder as the evaporation source,the Se/S atomic ratio in Sb₂（S,Se）₃thin films can be arbitrarily regulated.And the variation law between the components of evaporation source and the prepared films was summarized.By using this technology,the absorber layers with continuous adjustable band gap between 1.1 and 1.7 e V were successfully prepared,which lays a foundation for the subsequent regulation of the absorber layer band gap of Sb₂（S,Se）₃ thin film solar cells.2.The influence of gas path and thermal field design on thin film growth in vapor transport deposition system was studied.And a precise control scheme of the growth of micron size Sb₂（S,Se）₃ grains was explored.We clarified the growth mechanism of Sb₂（S,Se）₃ thin film,and investigated the effect of gaseous particle flux on the growth quality of thin films in the vapor transport deposition system.By regulating the gaseous particle flux,we had a good control of the growth rate of thin films and obtained Sb₂（S,Se）₃ thin films with full grains and uniform morphology.This study indicates the direction for the optimization of high quality absorber layers,and significantly improves the device performance of Sb₂（S,Se）₃ thin film solar cells.3.The deep-level defects in Sb₂（S,Se）₃ thin film solar cells were studied by the admittance spectroscopy for the first time,and the recombination mechanism of defects on photogenerated carriers was revealed.It was found that the activation energy of defects was the main factor affecting the photoelectric property of the devices.The mechanism of defects on the device performance was explained from the perspectives of capture cross section and capture time.The transport mode of gaseous particles in the vapor transport deposition process was further improved,which effectively promoted the nucleation growth of Sb₂（S,Se）₃ film and reduced the crystal defects in the absorber layer.Through process optimization,the fabricated Sb₂（S,Se）₃ thin film solar cells achieves an power conversion efficiency of 8.17%,which is the highest one among all inorganic Sb₂（S,Se）₃ thin film solar cells prepared by physical vapor deposition.4.Based on the serious interfacial diffusion problem of the preparation of Sb₂（S,Se）₃thin film solar cells with superstrate structure,a prefabricated layer induced crystal growth strategy was proposed to prevent the direct contact between the gaseous reaction particles and the Cd S buffer layer in vapor transport deposition system,which successfully inhibited the diffusion of interfacial elements.At the same time,the prefabricated layer can induce the growth of Sb₂（S,Se）₃ thin film,resulting in a promotion of the growth of grains and an improvement of the microstructure of the thin film.Finally the corresponding Sb₂（S,Se）₃ thin film solar cells achieved a higher open circuit voltage and filling factor.