No abstract

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.

Photocurrent voltage curves and photocurrent action spectra of bifacial inverted polymer solar cells with a structure of ITO/ZnO/[6,6]-phenyl C 61 butyric acid methyl ester (PCBM):regioregular poly(3-hexylthiophene) (P3HT)/poly(3,4ethylenedioxylenethiophene):poly(4-styrene sulfonic acid) (PEDOT:PSS)/Au were measured. High performance was obtained when light was irradiated from each side of the devices, even for those with a 500 nm thick PCBM:P3HT layer, but an optical filter effect of the photocurrent was somewhat larger for irradiation from the Au side than that for the ITO side. These results suggested that the efficiency of photocharge separation near the ZnO/PCBM:P3HT interface was higher than that near the PCBM:P3HT/PEDOT:PSS interface, although the photocharge separation and the charge transport were smooth in the whole PCBM:P3HT layer. Further, we found that the fill factor of the photocurrent voltage curves of these devices depended on the migration distance of holes with lower mobility in the PCBM:P3HT layer.