Narrow-bandgap diketo-pyrrolo-pyrrole polymer solar cells: The effect of processing on the performance

Solar cells based on a new conjugated donor polymer with alternating quaterthiophene and diketo pyrrolo-pyrrole units in combination with C-60 and C-70 PCBM acceptors afford high external quantum efficiencies over a broad spectral range into the near-infrared. The cells provide power conversion efficiencies of up to 4.0% under simulated AM1.5G solar light conditions.