Preparation Of Flexible CZTS Thin Film By Sol-gel Method And Its Photovoltaic Performance

Copper-zinc-tin-sulfur(Cu2ZnSnS4,CZTS)semiconductor components are rich and non-toxic.It has a forbidden bandwidth(1.4?1.5 e V)suitable for absorbing sunlight and a high light absorption coefficient(>10⁴ cm^-1).It is considered to be a very promising thin-film solar cell absorbing layer material.Manufacturing thin-film solar cells on flexible substrates can expand the application fields of solar cells and reduce manufacturing costs.The main problem of flexible CZTS thin film materials is that the stable phase region of CZTS thin film is relatively narrow,which is easy to produce impurities.At the same time,the flexible substrate is easy to induce the decomposition of the thin film during the vulcanization process and destroy the surface crystal.This paper will focus on these two issues to optimize the process.In this subject,the sol-gel vulcanization method was used to fabricate a CZTS film on the Mo substrate.By using sol-gel method,the subject analyzes the effects of sol thermal decomposition,environment,stabilizer,heat treatment temperature,and heat treatment time on the structure and morphology of the thin film during the preparation of the precursor film.The effects of annealing temperature and time on the phase structure,morphology,composition and optical band gap of the thin film during recrystallization were analyzed.Flexible CZTS thin-film solar cells were prepared from the prepared CZTS thin films according to the structure of Mo/Mo/CZTS/Cd S/i-Zn O/ITO/Ag.The photoelectric performance of the device was measured,and the relationship between the quality of the CZTS film and the photoelectric performance was revealed.Starting from the initial preparation of sol,CZTS sol was prepared with ethylene glycol methyl ether as the solvent,thiourea as the sulfur source of the sol,and copper acetate,zinc acetate and stannous chloride as the main solutes.The thermogravimetric analysis of different environments was used to explore the environment and temperature of the precursor film preparation.Based on this,CZTS precursor films were prepared on flexible substrates,and the effects of reaction atmosphere conditions on the structure and morphology of the films were explored.Then,different stabilizers were added to the sol,and triethanolamine with a molar concentration of 1%was determined as the best stabilizer.The effects of preheating temperature and preheating time on the phase structure and morphology of the film before and after curing were explored.The conclusion was that the best preheating temperature was 300?and the best preheating time was 120 s.Through the research of this subject,it is found that the best reaction environment of the flexible CZTS film during the preparation process is the atmospheric environment.The addition of TEA to the sol can improve the crystallinity of the film.The optimal heat treatment temperature is 300?and the treatment time is 120 s.The flexible CZTS film with Mo as the substrate is suitable for higher vulcanization temperature,and the best vulcanization temperature is 600?,and the vulcanization time is 80min.The surface of the flexible CZTS precursor film prepared by the sol-gel method is prone to cracks,but the surface defects can also be reduced by a step-by-step optimization method.The optimization of the vulcanization process significantly improves the crystal quality of the flexible CZTS film surface.Finally,the photoelectric conversion efficiency of the prepared solar cell was 3.47%.