Fabrication of Three-Dimensional-Structure Solar Cell with Cu2ZnSnS4

We fabricated three-dimensional (3D)-structure solar cells with Cu 2 ZnSnS 4 (CZTS). A CdS buffer layer was deposited around nc-TiO 2 by the chemical bath deposition (CBD) method. The CdS deposition time was varied from 5 to 30 min at 65 °C. CZTS absorber was deposited by spray pyrolysis deposition (SPD) onto the CdS buffer layer. Cu-, Zn-, Sn-, and S-containing solutions were used in SPD. The metal sources of copper(II) acetate monohydrate, zinc(II) acetate dehydrate, and tin(II) chloride dehydrate, and pure sulfur powder were desolved in N , N -dimethylformamide (DMF) as a solvent and mono-ethanolamine as a stabilizer. The solution-sprayed 3D-structure substrate was annealed in a nitrogen atmosphere at 250 °C for 30 min. A 3D-structure CZTS solar cell presented the best conversion efficiency $\eta$ of 0.51% with a CdS buffer layer deposition time of 20 min. The dependence of each solar cell characteristic on CdS buffer layer deposition time was measured.