Preparation of Cu 2 ZnSnS 4 Solar Cells by Sputtering Three Sulfide Targets at Different Sulfurization Annealing Temperatures

Cu 2 ZnSnS 4 (CZTS) thin films were prepared by sputtering three sulfide targets at different sulfurization annealing temperatures from 550 to 600 ℃. The morphology, microstructure and optical-electrical properties of CZTS thin films were investigated. It was found that the crystal quality at the CZTS/Mo interface without intermediate layers was promising and the thickness of MoS 2 was limited to within 90 nm. The expected results were achieved after 575 ℃ sulfurization annealing, indicating that sputtering three sulfide targets can compensate for part of the sulfur partial pressure in the sulfurization process. The measurements showed that CZTS thin film (called S 2 ) sulfurized at 575 ℃ with a mobility of 282.7 cm 2 /V·s and a band gap of 1.49 eV had the best electrical and optical properties. The elemental depth profile showed that the composition in S 2 was homogeneously distributed. Finally, the CZTS solar cell with an active area 0.8 cm 2 was successfully fabricated and the conversion efficiency was 2.7%. The max external quantum efficiency exhibited a value of 79.7%. The short-circuit current density and open-circuit voltage of the device were 20.12 mA/cm 2 and 381 mV, respectively. The relationship between the composition and the voltage deficit was also discussed.