Over 9% Efficient Kesterite Cu₂ZnSnS₄ Solar Cell Fabricated by Using Zn_1–<i>_x</i>Cd<i>_x</i>S Buffer Layer

Abstract

A kesterite Cu2ZnSnS4 thin film solar cell with efficiency of over 9% is obtained by utilizing Zn1–xCdxS film as a replacement to traditional CdS buffer layer. Zn1–xCdxS film can optimize the conduction band offset between Cu2ZnSnS4 absorber and buffer, forming a minor positive conduction band alignment, thereby alleviating the recombination significantly and improving the open circuit voltage and fill factor efficiently.