Enhanced Carrier Collection from CdS Passivated Grains in Solution-Processed Cu2ZnSn(S,Se)4 Solar Cells

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• 作者：Melanie Werner ; Debora Keller ; Stefan G. Haass ; Christina Gretener ; Benjamin Bissig ; Peter Fuchs ; Fabio La Mattina ; Rolf Erni ; Yaroslav E. Romanyuk ; Ayodhya N. Tiwari
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：June 10, 2015
• 年：2015
• 卷：7
• 期：22
• 页码：12141-12146
• 全文大小：392K
• ISSN：1944-8252

文摘

Solution processing of Cu₂ZnSn(S,Se)₄ (CZTSSe)鈥搆esterite solar cells is attractive because of easy manufacturing using readily available metal salts. The solution-processed CZTSSe absorbers, however, often suffer from poor morphology with a bilayer structure, exhibiting a dense top crust and a porous bottom layer, albeit yielding efficiencies of over 10%. To understand whether the cell performance is limited by this porous layer, a systematic compositional study using (scanning) transmission electron microscopy ((S)TEM) and energy-dispersive X-ray spectroscopy of the dimethyl sulfoxide processed CZTSSe absorbers is presented. TEM investigation revealed a thin layer of CdS that is formed around the small CZTSSe grains in the porous bottom layer during the chemical bath deposition step. This CdS passivation is found to be beneficial for the cell performance as it increases the carrier collection and facilitates the electron transport. Electron-beam-induced current measurements reveal an enhanced carrier collection for this buried region as compared to reference cells with evaporated CdS.