Hierarchical Cu2ZnSnS4 Particles for a Low-Cost Solar Cell: Morphology Control and Growth Mechanism

In this paper, novel hierarchical Cu2ZnSnS4 (CZTS) particles were synthesized by a solvothermal method. The effects of synthetic conditions, such as reaction temperature, reaction time, solution concentration, and the amount of PVP, were investigated. The results showed that the size and morphology of the CZTS particles can be controlled by changing the reaction conditions and that PVP played an important role in the formation of the final hierarchical particles. Time-dependent results showed that the nucleation and growth of the CZTS particles were governed by a nucleation-dissolution-recrystallization growth mechanism. The optical and electrical properties of the CZTS particles were also investigated. Compared with spherelike CZTS particles and CZTS nanocrystals, the absorption of typical hierarchical CZTS particles decayed more slowly, indicating a higher absorption coefficient in the visible region. Meanwhile, the current-voltage characteristics of the CZTS films indicated that flowerlike particles favored the electronic transmission and thus may induce the generation of photocurrent. Thus, the obtained hierarchical CZTS particles are more suitable for using as an absorber layer in low-cost solar cells.