Applied Surface Science, Vol.383, 253-260, 2016
One-step electrodeposition for targeted off-stoichiometry Cu2ZnSnS4 thin films
Cu2ZnSnS4 (CZTS) is a promising quaternary compound suitable for absorber layer of thin film solar cells. The precise control of the atomic ratio of the films are difficult for the electrodeposition of CZTS thin films. Here, we reported targeted off-stoichiometry CZTS thin films synthesized by one-step electrode position. We obtained Cu-poor thin films and the chemical composition of the as-deposited thin films were tailored to targeted off-stoichiometry. Based on the different kinetics of the metallic ion reduction, we successfully controlled the chemical composition by varying deposition time. After annealing, pure kesterite structure was obtained and the electronic interactions between Cu and Sn was verified in the films, which contributes to high carrier mobility. The band gap of the thin films were in the range of 1.43-1.52 eV, which is suitable for absorber layers of thin film solar cells. The carrier mobility reached a value of 28.20 cm(2)/V s with carrier concentration of 2.09 x 10(18) cm(-3) when Cu/(Zn + Sn) and Zn/Sn ratios were 0.97 and 1.13, respectively. This work paves a way for synthesizing targeted off-stoichiometry compounds by controlling kinetics and reaction time in large scale. (C) 2016 Elsevier B.V. All rights reserved.
Keywords:Cu2ZnSnS4;Thin film;One-step electrodeposition;Off-stoichiometry;Kesterite;Electronic interaction