Temperature-Modulated Nucleation Engineering Enables Uniform Distribution of Cations for Efficient Kesterite Solar Cells

Kesterite Cu₂ZnSn(S,Se)₄ (CZTSSe) has emerged as a highly promising photovoltaic material because of its environmentally friendly characteristics and low cost. However, as a multicomponent inorganic semiconductor material, the complex nature of CZTSSe leads to disorder in the crystallization reaction process at high-temperature selenization, resulting in numerous antisite defects that cause significant non-radiative recombination and open circuit voltage loss of the final photovoltaic device. Therefore, it is a great challenge to fabricate high-quality CZTSSe absorbers with homogeneous chemical composition and uniform cation distribution for achieving high-efficiency solar cells. Herein, synergistic crystallization and uniform cation distribution have been successfully realized via temperature-modulated homogeneous nucleation strategy. This strategy effectively leads to more homogeneous nucleation sites with larger nuclei sizes for high-quality CZTSSe thin films with uniform cation distribution. As a result, high-efficiency CZTSSe solar cells over 14% have been realized. This work reveals the mechanism of uniform nucleation, providing a simple and feasible route for high-quality CZTSSe thin films and high-efficiency CZTSSe solar cells.