Recombination Dynamics as a Key Determinant of Open Circuit Voltage in Organic Bulk Heterojunction Solar Cells: A Comparison of Four Different Donor Polymers - Maurano, A; Hamilton, R; Shuttle, CG; Ballantyne, AM; Nelson, J; O'Regan, B; Zhang, W; McCulloch, I; Azimi, H; Morana, M; Brabec, CJ; Durrant, JR (ADVANCED MATERIALS, 2010)