High device performance is demonstrated in air-processed polymersolar cells made from an active layer of poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester, with optimized efficiency and fill factor as high as 4.71% and 0.71, respectively. The degree of self-organization of the active layer can be varied by controlling the solvent evaporation rate at different room temperature (298–292 K). Device performance improvement originates from an increased absorption and increased charge-carrier mobility in the active layer. This free-annealing process compatible with flexible substrates contributes to a flexible cell with an efficiency of 4.06%.
Received 17 October 2012Accepted 14 January 2013Published online 01 February 2013
This work was supported by the National Basic Research Program of China (Grant No. 2011CBA00705), NSFC (Grant No. 11174163), and the Scholarship Award for Excellent Doctoral Student granted by Ministry of Education. Z. Hu would like to thank the sponsored by K.C. Wong Magna Fund in Ningbo University.