The influence of polymer purification on photovoltaic device performance of a series of indacenodithiophene donor polymers

Raja Shahid Ashraf, Bob C. Schroeder, Hugo A. Bronstein, Zhenggang Huang, Stuart Thomas, R. Joseph Kline, Christoph J. Brabec, Patrice Rannou, Thomas D. Anthopoulos, James R. Durrant, Iain McCulloch