An inverted bifacial polymer solar cell was developed using a conductivity-controlled transparent PEDOT:PSS as a hole collection layer and a striped Au electrode with a large open aperture ratio (Rap) as a hole collection electrode. We investigated the performance of the device by varying the inter-electrode distance of the striped Au electrode and the sheet resistance of the PEDOT:PSS film.The device using Clevios P (PEDOT:PSS) showed a maximum electric output (P w ) in the R ap range of 50 to 65 %. When alcohol-treated Clevios P (Clevios P+) with a lower electrical resistance was used, the maximum P w increased by 40 % compared with that of the device using Clevios P. The maximum P w was obtained in the R ap range of 84 % as the hole collection efficiency of the striped Au electrode improved with the decreased sheet resistance of the PEDOT:PSS.

Polymers consisting of benzo[1,2‐b:4,5‐b′]dithiophene and thieno[3,4‐b]thiophene units (PTB‐based polymers), either fully or partially containing 4‐fluorophenyl pendants, are synthesized as electron donor materials for inverted‐type polymer solar cells (PSCs). The influence of the 4‐fluorophenyl pendant content on the thermal and optical properties, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), the hole mobilities, and photovoltaic performances are investigated. As the 4‐fluorophenyl pendant content increased, the HOMO and LUMO of the polymers were deepened proportionally and the open‐circuit voltages of the PSCs improved. Incorporation of 4‐fluorophenyl pendants into the polymers also affected the crystallinity, orientation, and compatibility with [6,6]‐phenyl‐C61‐butyric acid methyl ester in the active layers, leading to nonlinearities in the short‐circuit current densities, and fill factors. The incorporation of an appropriate number of 4‐fluorophenyl pendants enhanced the power conversion efficiencies of the PSC devices from 2.25 to 3.96% for identical device configurations. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1586–1593