Study On CIGS Solar Cell Based On Flexible Substrate

Solar power is an inexhaustible clean enery. Improving the photoelectric conversion efficiency and reducing production costs are the pursuing goal in the field of photovoltaic cells. Cu(In,Ga)Se2 thin film solar cell possesses highest efficiency in a variety of thin film solar cells, and is one of the most promising thin-film solar cells.In recent years, more and more attention has been paid to thin film solar cells based on flexible substrates.Many companies and research institutions in the world are racing to study flexible solar cells. Compared to the hard substrate solar cells, flexible solar cell is lightweight, collapsible, not fragile, and has a higher mass specific power(500W/kg).The main fabricating method used is automation roll to roll process. There are some key problems which are urgent to resolve for thin film solar cells based on flexible substrates.There exists a large gap between China and developed countries in this field.Firstly. the theory, structure, recent development and performance of solar cell were introduced in this paper. On the basis of extensive research on the preparation process and technical route, polyimide was used as the substrate of the solar cell.The polyimide thin film with good stability in high temperature was prepared by spin-coating. The CIGS absorber layer was prepared by RF magnetron sputtering using CIGS target.Several single experiments such as the preparation and selection of flexible substrate, contact electrode Mo,absorbing layer layer CIGS, buffer layer CdS were studied respectively.The influences of the sputtering Ar pression, substrate temperature, annealing conditions and solutions ratio were investigated. Surface topography was observed by SEM.The crystal structure of CIGS thin film was analyzed by XRD method,Transmission spectra and electric resistivity were also tested in this paper.Double layer Mo electrode was prepared on flexible PI substrate by RF sputtering process,which has excellent bonding and low resistivity.The mismatch of the thermal expansion coefficient between the polyimide and the CIGS layers results in the crack of CIGS thin film.By depositing CIGS thin film on heated substrate.CIGS thin film which has good combination with Mo was prepared. Finally, by the process integration, we prepared CIGS multilayer film solar cell based on flexible substrate.The test results showed that the cell has a certain degree of conversion efficiency, but the performance was yet to be improved.