Title: Complex Interplay between Absorber Composition and Alkali Doping in High-Efficiency Kesterite Solar Cells Authors: Stefan G. Haass,* Christian Andres, Renato Figi, Claudia Schreiner, Melanie Bürki, Yaroslav E. Romanyuk, and Ayodhya N. Tiwari Link (Open Acess): Adv. Energy Mater. 2018, 8, 1701760 Abstract: Sodium treatment of kesterite layers is a widely used and efficient method to boost solar cell efficiency. However, first experiments employing other alkali elements cause confusion as reported results contradict each other. In this comprehensive investigation, the effects of absorber composition, alkali element, and concentration on optoelectronic properties and device performance are investigated. Experimental results show that in the row…