Tailoring Dual Interface Performance Drives Highly Efficient Kesterite Solar Cells: Breaking the Limitations of V OC and J SC

The unsatisfactory interface performance, especially for multi‐layer structured kesterite devices, is an important factor limiting the progress of solar cell technology. In this work, a synergistic strategy to tailor the dual interface performance and manage the behavior of photo‐generated charge carriers has been developed, consisting of Cd doping and atomic‐layer deposited aluminum oxide (ALD‐Al 2 O 3 ). With this strategy, the open‐circuit voltage ( V OC ) and short‐circuit current density ( J SC ) are simultaneously increased, and the photoelectric conversion efficiency of kesterite thin‐film solar cells is improved by 36%. The crystal growth and surface photoelectric properties of the absorber are adjusted by Cd doping, thereby enhancing light absorption. Subsequent Al 2 O 3 optimizes the element distribution and defect characteristics, improves recombination loss and back contact barrier. This strategy not only increases the concentration of p‐type carriers in the absorber and enhances the separation electric field between holes and electrons but also improves the dual interface transport characteristics, thereby managing the behavior of photo‐generated carriers from multiple perspectives and promoting effective charge collection. It breaks through the dilemma of single growth of V OC or J SC in photovoltaic devices, and the regulation of dual interfaces holds promise for advancing the development of efficient thin‐film devices and stacked solar cells.