Red-Absorbing Cationic Acceptor Dyes for Photocathodes in Tandem Solar Cells

• Published in: Journal of physical chemistry. C 2014-07, Vol.118 (30), p.16536-16546
• Main Authors: Wood, Christopher J, Cheng, Ming, Clark, Charlotte A, Horvath, Raphael, Clark, Ian P, Hamilton, Michelle L, Towrie, Michael, George, Michael W, Sun, Licheng, Yang, Xichuan, Gibson, Elizabeth A
• Format: Article
• Language: English
• Subjects: Computational model; Dye-Sensitized solar cell; Dye-sensitized solar cells; Electrodes; Field emission cathodes; Photons; Short-circuit photocurrent densities; Tandem solar cells; Time resolved infrared spectroscopy; Transient absorption; Ultra-fast; Visible spectra
• ISSN: 1932-7447; 1932-7455; 1932-7455
• DOI: 10.1021/jp4119937

A pair of new donor−π–acceptor dyes that absorb toward the red region of the visible spectrum (CAD 1 and CAD 2) utilizing indolium cationic acceptor units have been synthesized for use in p-type dye-sensitized solar cells (p-DSC). Their optical and electrochemical properties were determined experimentally, including application of ultrafast transient absorption and time-resolved infrared spectroscopies. Our results are supported by computational modeling. NiO-based p-DSCs with CAD 1 and CAD 2 gave short-circuit photocurrent densities of 3.6 and 3.3 mA cm–2, respectively, which are substantially higher than that of any previous red-absorbing p-DSC. These results are a step toward tandem dye-sensitized solar cells that absorb higher-energy photons at the TiO2 anode and lower-energy photons at the NiO cathode. Routes to further improve the efficiency of NiO DSCS are also discussed.