Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 May 27;12(21):23923-23930.
doi: 10.1021/acsami.0c04117. Epub 2020 May 14.

Efficiency Considerations for SnO2-Based Dye-Sensitized Solar Cells

Brian N DiMarco  1 , Renato N Sampaio  1 , Erica M James  1 , Timothy J Barr  1 , Marc T Bennett  1 , Gerald J Meyer  1
Affiliations

Efficiency Considerations for SnO2-Based Dye-Sensitized Solar Cells

Brian N DiMarco et al. ACS Appl Mater Interfaces. .

Abstract

A comparative study of mesoporous thin films based on SnO2 (rutile) and TiO2 (anatase) nanocrystallites sensitized to visible light with [Ru(dtb)2(dcb)](PF6)2, where dtb = 4,4'-(tert-butyl)2-2,2'-bipyridine and dcb = 4,4'-(CO2H)2-2,2'-bipyridine, in CH3CN electrolyte solutions is reported to identify the reason(s) for the low efficiency of SnO2-based dye-sensitized solar cells (DSSCs). Pulsed laser excitation resulted in rapid excited state injection (kinj > 108 s-1) followed by sensitizer regeneration through iodide oxidation to yield an interfacial charge separated state abbreviated as MO2(e-)|Ru + I3-. Spectral features associated with I3- and the injected electron MO2(e-) were observed as well as a hypsochromic shift of the metal-to-ligand charge-transfer absorption of the sensitizer attributed to an electric field. The field magnitude ranged from 0.008 to 0.39 MV/cm and was dependent on the electrolyte cation (Mg2+ or Li+) as well as the oxide material. Average MO2(e-) + I3- → recombination rate constants quantified spectroscopically were about 25 times smaller for SnO2 (6.0 ± 0.14 s-1) than for TiO2 (160 ± 10 s-1). Transient photovoltage measurements of operational DSSCs indicated a 78 ms lifetime for electrons injected into SnO2 compared to 27 ms for TiO2; behavior that is at odds with the view that recombination with I3- underlies the low efficiencies of nanocrystalline SnO2-based DSSCs. In contrast, the average rate constant for charge recombination with the oxidized sensitizer, MO2(e-)|-S+ → MO2|-S, was about 2 orders of magnitude larger for SnO2 (k = 9.8 × 104 s-1) than for TiO2 (k = 1.6 × 103 s-1). Sensitizer regeneration through iodide oxidation were similar for both oxide materials (kreg = 6 ± 1 × 1010 M-1 s-1). The data indicate that enhanced efficiency from SnO2-based DSSCs can be achieved by identifying alternative redox mediators that enable rapid sensitizer regeneration and by inhibiting recombination of the injected electron with the oxidized sensitizer.

Keywords: SnO2; charge recombination; dye-sensitized solar cells; sensitizer regeneration.

PubMed Disclaimer

LinkOut - more resources