Abstract
Solid-state dye sensitized solar cells (SDSCs) with a power conversion efficiency of 3.85% have been fabricated using an organic indoline dye D131 as the sensitizer and poly(3-hexylthiophene) (P3HT) as the hole transporter, which represent one of the most efficient SDSCs using polymeric hole transporter. UV−vis and the incident photon-to-current conversion efficiency (IPCE) spectra indicate that P3HT almost only acts as the hole transporter to regenerate oxidized D131 and has little contribution to the photocurrent. Impedance spectroscopy is further employed to investigate charge transport and recombination kinetics in these cells. The electron diffusion length (Ln) is found to be obviously larger than TiO2 film thickness, resulting in efficient charge collection. However, the hole conductivity in P3HT is 1 order of magnitude lower than electron conductivity in TiO2, leading to relatively poor fill factors. This work represents the first systematic study of charge transport and recombination in SDSCs using conjugated polymer hole transporter, which sheds light on understanding the operation of highly efficient solid-state devices.