Photocurrent enhancement from diketopyrrolopyrrole polymer solar cells through alkyl-chain branching point manipulation. - Meager, I; Ashraf, RS; Mollinger, S; Schroeder, BC; Bronstein, H; Beatrup, D; Vezie, MS; Kirchartz, T; Salleo, A; Nelson, J; McCulloch, I (J Am Chem Soc, 2013)