Perovskite solar cells for roll-to-roll fabrication Ashraf Uddin, Md Arafat Mahmud, Naveen Kumar Elumalai, Dian Wang, Mushfika Baishakhi Upama, Matthew Wright, Kah Howe Chan, Faiazul Haque and Cheng Xu Renew. Energy Environ. Sustain., 2 (2017) 7 Published online: 24 August 2017 DOI: 10.1051/rees/2017019