Reduced voltage losses yield 10% efficient fullerene free organic solar cells with >1 V open circuit voltages

D. Baran, T. Kirchartz, S. Wheeler, S. Dimitrov, Maged Abdelsamie, J. Gorman, Raja Ashraf, S. Holliday, A. Wadsworth, N. Gasparini, P. Kaienburg, H. Yan, Aram Amassian, C. J. Brabec, J. R. Durrant, Iain McCulloch