Enhanced Hetero‐Junction Quality and Performance of Kesterite Solar Cells by Aluminum Hydroxide Nanolayers and Efficiency Limitation Revealed by Atomic‐resolution Scanning Transmission Electron Microscopy

The research leading to these results has received funding from Generalitat de Catalunya 2014SGR1638 and the Spanish MINECO (Ministerio de Economia y Competitividad de Espana) under the NASCENT (ENE2014‐56237‐C4‐1‐R), the TNT‐FUELS and e‐TNT (MAT2014‐59961) projects, funding from the Framework 7 program under the project KESTCELLS (FP7‐PEOPLE‐2012‐ITN‐316488) and European Regional Development Founds (ERDF, FEDER Programa Competitivitat de Catalunya 2007–2013). Authors from IREC and IN2UB belong to the M‐2E (Electronic Materials for Energy) Consolidated Research Group and the XaRMAE Network of Excellence on Materials for Energy of the “Generalitat de Catalunya”. H. Xie thanks the “China Scholarship Council” fellowship (CSC N° 201206340113), Y. S. the MINECO for the PTA fellowship (PTA2012‐7852‐A), and E.S. the “Ramon y Cajal” fellowship (RYC‐2011‐09212). ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV‐2013‐0295).