Effect of annealing temperature on a single step processed Cu2ZnSnS4 thin film via solution method

• Prepared CZTS film through one-step liquid based approach using non-toxic chemicals.
• Studied the effect of N2 annealing on structural, optical and electrical properties.
• The phase pure CZTS absorber film exhibited excellent photovoltaic properties
• The film annealed at 500 °C for 30 min in nitrogen exhibited optimum properties.

Cu2ZnSnS4 (CZTS) is a promising material for thin film solar cell applications because of its excellent photovoltaic properties, high abundance and non-toxicity. Thin films of CZTS are generally fabricated by vacuum based techniques or by using toxic solvents and these routes reduce its attention as a low cost and environmental friendly material. In this study, we have prepared CZTS through a solution based single step approach using non-toxic chemicals by spin coating and studied the effect of annealing temperature in the range 350–550 °C in nitrogen atmosphere on structural, optical and electrical properties. XRD results revealed the formation of kesterite phase at all annealing temperatures, while the Raman studies indicated Cu2SnS2 impurity phase in the film annealed at 550 °C. Band gap of the films annealed in nitrogen varies from 1.46 eV to 1.56 eV, depending on the annealing temperature. Optimum properties, such as, good crystallinity, dense structure, ideal band gap (1.49 eV) and good absorption coefficient (104 cm− 1), were obtained for the film annealed at 500 °C for 30 min in nitrogen.