Bandgap-Graded Cu2Zn(Sn1鈥?i>xGex)S4 Thin-Film Solar Cells Derived from Metal Chalcogenide Complex Ligand Capped Nanocrystals

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• 作者：Inhyuk Kim ; Kyujin Kim ; Yunjung Oh ; Kyoohee Woo ; Guozhong Cao ; Sunho Jeong ; Jooho Moon
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：July 8, 2014
• 年：2014
• 卷：26
• 期：13
• 页码：3957-3965
• 全文大小：495K
• ISSN：1520-5002

文摘

We demonstrate organic residue free, bandgap-graded Cu₂Zn(Sn_1鈥?i>xGe_x)S₄ (CZTGeS) thin-film solar cells based on metal chalcogenide complex (MCC) ligand capped nanocrystals (NCs). The bandgap of the CZTGeS films is tuned by varying the amount of Sn₂S₆^{4鈥?/sup> MCC ligand absorbed on the surface of the Cu₂ZnGeS₄ (CZGeS) NCs, without an undesirable postselenization process. Using CZGeS NCs inks with three different Sn/(Ge+Sn) ratios, bandgap-graded CZTGeS thin films are obtained via multicoating and annealing procedures. Compositional and spectroscopic analyses along the film thickness confirm that the band-graded CZTGeS absorber layer, with a gradually increasing bandgap from the back contact to the p鈥?i>n junction, is successfully accomplished. Compared with an ungraded band structured CZTGeS cell, this normal grading structure facilitates both higher short circuit current and open-circuit voltage, facilitating a power conversion efficiency of 6.3%.}