High-efficient Cd-free CZTS solar cells achieved by nanoscale atomic layer deposited aluminium oxide

摘要

Kesterite Cu₂ZnSnS₄ (CZTS) solar cells are considered as the promising alternative candidate for thin film solar cells, but still being hampered by the relative low V_OC. Here, we propose a heterojunction modification strategy by applying atomic layer deposited aluminium oxide (Al₂O₃) as a passivation layer. Through post-treatment of CZTS absorber by nanoscale ALD Al₂O₃, the effective lifetime of the minority carrier at the heterojunction improved, indicating a better passivation effects from nanoscale alumina. With a significant gain of Voc by 50 mV, we achieved a device efficiency of 9.9 %, the highest efficiency ever reported for Cd-free CZTS solar cells.