First observation of sol-gel derived Al:CsZnO/CsZnO bilayer thin film for solar cells application Mehdi Ahmadi, Sajjad Rashidi Dafeh and Saeid Alinazmabadi Eur. Phys. J. Plus, 131 10 (2016) 354 Published online: 10 October 2016 DOI: 10.1140/epjp/i2016-16354-5