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

Adèle Debono; Filipe Martinho; Jørgen Schou; Stela Canulescu

doi:10.1021/acsomega.4c07483

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

ACS Omega. 2024 Dec 10;9(51):50439-50445. doi: 10.1021/acsomega.4c07483. eCollection 2024 Dec 24.

Authors

Adèle Debono¹, Filipe Martinho¹, Jørgen Schou¹, Stela Canulescu¹

Affiliation

¹ Department of Electrical and Photonics Engineering, Technical University of Denmark, Roskilde 4000, Denmark.

Abstract

This study examines the effect of ultrathin aluminum oxide (Al₂O₃) passivation layer on the performance of the kesterite Cu₂ZnSnS₄ (CZTS) solar cells. The Al₂O₃ layer was applied at the back CZTS/Mo interface using atomic layer deposition (ALD). Our findings indicate that the interface passivation with Al₂O₃ can significantly enhance the adhesion of CZTS to Mo, preventing delamination during annealing. An optimal Al₂O₃ 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 Al₂O₃ layer modified MoS₂ formation at the CZTS/Mo back interface, reducing series resistance (R _s). Nevertheless, a thicker Al₂O₃ 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 Al₂O₃ layer thickness is essential to optimize CZTS solar cell performance by balancing the benefits of passivation with its potential drawbacks.