Control of metal salt ratio and MoS_2 layer thickness in a Cu_2ZnSnS_4 thin film solar cell

摘要

Cu_2ZnSnS_4 (CZTS) absorber layers were prepared from copper acetate, zinc acetate, tin chloride, and thiourea in a solution of methanol, ethylenediamine, and ethanolamine using a sol-gel spin-coating method. Sol-gel precursor solutions were prepared with different metal salt ratios, and the effects on film growth, optical properties, and crystal properties of CZTS films were investigated. In addition, the role of sulfurization temperature on grain size of CZTS and formation of the MoS_2 layer at the CZTS and Mo interface were investigated. By changing the metal salt ratio in the precursor solution, a Zn-rich and Cu-poor condition in the CZTS film was obtained. By preparing Zn-rich and Cu-poor CZTS film with a thinner MoS_2 layer at a lower sulfurization temperature, the CZTS cell efficiency was improved, and a conversion efficiency of 1.22 % was obtained.