Easy and low-cost aqueous precipitation method to obtain Cu2ZnSn(S, Se)4 thin layers

An easy method to obtain kesterite Cu2ZnSn(Se1-x,Sx)4 (CZTSSe) solid solution as an absorber for thin film photovoltaic solar cells is discussed in this report. Particular emphasis is directed toward the procedure´s steps of the CZTSSe preparation, as well as its structure and properties. For the preparation of CZTSSe an easy, low-cost and sustainable aqueous precipitation method that included chemical transformations of metal selenite precipitate, its reduction to metal selenides and further crystallization of kesterite, is applied. This procedure is more viable as avoids the use of selenization treatment and thus generation of toxic vapors and employs water as a solvent instead of organic compounds. In addition, the proposed procedure is very attractive way of preparation for industrial large-scale fabrication of the most promising absorber candidates for photovoltaic thin film solar cells. Kesterite CZTSSe solid solution has been prepared and characterized in terms of chemical composition, structural and morphological transformations, as well as optical and electrical properties, confirming the viability and effectiveness of the applied process. The optimal electrical parameters obtained of the device are 21.5 mA/cm2, 532 mV, 42.8%., and 4.9% to short circuit current (Jsc), open circuit voltage (Voc), fill factor (FF), and efficiency (Eff.) respectively. Detailed description of each procedure steps and full characterization of the products, starting from as-prepared, intermediate and final compound is also exposed that could be very useful for any experimental scientist.The authors would like to acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness under the programs RETOS-COLABORACION (RTC-2014–2294-3) and RETOS-INVESTIGACIÓN (ENE2013-49136-C4-2-R). We also appreciate the characterization assistance of Central Service of Scientific Instrumentation (SCIC) at the University Jaume I and Catalonia Institute for Energy Research (IREC) for them help in the Raman measurements and solar cell asembly. R. Martí would like to acknowledge the economic support of the FPI-UJI grand (Formación del personal investigator-Universidad Jaume I)