Preparation And Properties Of Buffer Layers And CZTSSe Absorbing Layers For Solar Cells

CZTSSe materials have excellent performances and characteristics which attract many research institutions'and scholars'attention,because it has appropriate band gap?1.0 eV¹.5 eV?,large photoabsorption coefficient(104 cm^-1),and the elements contained are earth-abundant.But usually as its buffer layer cadmium sulfide?Cd S?has bad influence on the environment,developing an alternative non-toxic buffer layer to replace Cd S is also the main object for the researchers.So this paper mainly discusses the non-toxic Zn-Sn-O buffer layer and preparation and properties of CZTSSe thin film.Firstly,Zn-Sn-O buffer layer was prepared by dual targets?ZnO?Sn O₂?alternate sputtering and annealing through pulse lazer sputtering method.The best film property was obtained by changing substrate temperature,power of laser,annealing temperature,and ratio of sputtering.The results showed that film were smoother and denser when substrate temperature,power of laser were 500?and 400 mJ,respectively.The film's average transmittance was over 80%in the range of visible light?400 nm⁸00 nm?.Band gap was about 3.2 eV.The film's performance was better after annealing in the air.The average transmittance was over 83%when the sputtering ratio was 0.15.The square resistance is 480?/.Secondly,CZTS precursor solution was produced by a non-toxic solution approach and the film were obtained by spin coating and selenylation process.The results showed that the film got best performance when selenide temperature,selenium powder quality and time were 540?,100 mg and 10 min,respectively.The preferable growth face of CZTSSe with kesterite structure was?112?.To further investigate the influence of element Na to the CZTSSe crystal structure,a few drop of Na salt solution with two concentrations was added into the precursor,the result showed that the crystallinity of the deposited films was enhanced after selenylation at the same condition.