Effect of Interface Passivation on the Performance of the Cu2ZnSnS4 Solar Cells

High Resolution Image Download MS PowerPoint Slide This study examines the effect of ultrathin aluminum oxide (Al 2 O 3 ) passivation layer on the performance of the kesterite Cu 2 ZnSnS 4 (CZTS) solar cells. The Al 2 O 3 layer was applied at the back CZTS/Mo interface using atomic layer deposition (ALD). Our findings indicate that the interface passivation with Al 2 O 3 can significantly enhance the adhesion of CZTS to Mo, preventing delamination during annealing. An optimal Al 2 O 3 thickness of 1–2.5 nm yielded a more than 30% increase in efficiency, primarily through enhancements of the open-circuit voltage ( V oc ) and short-circuit current ( I sc ), which resulted from reduced interface recombination and improved charge collection within the CZTS bulk. Furthermore, the Al 2 O 3 layer modified MoS 2 formation at the CZTS/Mo back interface, reducing series resistance ( R s ). Nevertheless, a thicker Al 2 O 3 layer led to a sharp decrease in efficiency due to increased series resistance and hindered the extraction of holes. Our work reveals that precise control of the Al 2 O 3 layer thickness is essential to optimize CZTS solar cell performance by balancing the benefits of passivation with its potential drawbacks.