Four new molecular donors are reported using a D1-A-D2-A-D1 structure, where D1 is an oligiothiophene, A is a benzothiadiazole, and D2 is indacenodithieno[3,2-b]thiophene. The resulting materials provide efficiencies as high as 6.5% in organic solar cells, without the use of solvent additives or thermal/solvent annealing. A strong correlation between the end group (D1-A) dipole moment and the fill factor (FF), mobility, and loss in the open-circuit voltage (V-OC) is observed. Indacenodithieno[3,2-b]thiophene-fluorobenzothiadiazole-terthiophene (IDTT-FBT-3T) possesses the largest end group dipole moment, and in turn, has the highest mobility, FF, and power conversion efficiency in devices. It also has a similarly high V-OC (0.95 V) to the other materials (0.93-0.99 V), despite possessing a much higher highest occupied molecular orbital (HOMO) energy level.