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Initial Light Soaking Treatment Enables Hole Transport Material to Outperform Spiro-OMeTAD in Solid-State Dye-Sensitized Solar Cells
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
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2013 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 19, 7378-7385 p.Article in journal (Refereed) Published
Abstract [en]

Efficient solid state dye-sensitized solar cells (sDSCs) were obtained using a small hole transport material, MeO-TPD (N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine), after an initial light soaking treatment. It was discovered that the light soaking treatment for the MeO-TPD based solar cells is essential in order to achieve the high efficiency (4.9%), which outperforms spiro-OMeTAD based sDSCs using the same dye and device preparation parameters. A mechanism based on Li+ ion migration is suggested to explain the light soaking effect. It was observed that the electron lifetime for the MeO-TPD based sDSC strongly increases after the light soaking treatment, which explains the higher efficiency. After the initial light soaking treatment the device efficiency remains considerably stable with only 0.2% decrease after around 1 month (unsealed cells stored in dark).

Place, publisher, year, edition, pages
2013. Vol. 135, no 19, 7378-7385 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-202919DOI: 10.1021/ja403344sISI: 000319250200042OAI: oai:DiVA.org:uu-202919DiVA: diva2:634540

De två (2) första författarna delar förstaförfattarskapet.

Available from: 2013-07-01 Created: 2013-07-01 Last updated: 2014-10-22
In thesis
1. Hole Transport Materials for Solid-State Mesoscopic Solar Cells
Open this publication in new window or tab >>Hole Transport Materials for Solid-State Mesoscopic Solar Cells
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The solid-state mesoscopic solar cells (sMSCs) have been developed as a promising alternative technology to the conventional photovoltaics. However, the device performance suffers from the low hole-mobilities and the incomplete pore filling of the hole transport materials (HTMs) into the mesoporous electrodes. A variety of HTMs and different preparation methods have been studied to overcome these limitations. There are two types of sMSCs included in this doctoral thesis, namely solid-state dye-sensitized solar cells (sDSCs) and organometallic halide perovskite based solar cells.

Two different types of HTMs, namely the small molecule organic HTM spiro-OMeTAD and the conjugated polymer HTM P3HT, were compared in sDSCs. The photo-induced absorption spectroscopy (PIA) spectra and spectroelectrochemical data suggested that the dye-dye hole conduction occurs in the absence of HTM and appears to be of significant importance to the contribution of hole transport.

The PIA measurements and transient absorption spectroscopy (TAS) indicated that the oxidized dye was efficiently regenerated by a small molecule organic HTM TPAA due to its excellent pore filling. The conducting polymer P3HT was employed as a co-HTM to transfer the holes away from TPAA to prohibit the charge carrier recombination and to improve the hole transport.

An alternative small molecule organic HTM, MeO-TPD, was found to outperform spiro-OMeTAD in sDSCs due to its more efficient pore filling and higher hole-mobility. Moreover, an initial light soaking treatment was observed to significantly improve the device performance due to a mechanism of Li+ ion migration towards the TiO2 surface.

In order to overcome the infiltration difficulty of conducting polymer HTMs, a state-of-the-art method to perform in-situ photoelectrochemical polymerization (PEP) in an aqueous micellar solution of bis-EDOT monomer was developed as an environmental-friendly alternative pathway with scale-up potential for constructing efficient sDSCs with polymer HTMs.

Three different types of HTMs, namely DEH, spiro-OMeTAD and P3HT, were used to investigate the influence of HTMs on the charge recombination in CH3NH3PbI3 perovskite based sMSCs. The photovoltage decay measurements indicate that the electron lifetime (τn) of these devices decreases by one order of magnitude in the sequence τspiro-OMeTAD > τP3HT > τDEH.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 110 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1181
mesoscopic solar cells, solid-state dye-sensitized solar cells, organometallic halide perovskite, hole transport materials, mesoporous TiO2, conjugated polymer, sensitizer, transient absorption spectroscopy, photo-induced absorption spectroscopy, in-situ photoelectrochemical polymerization, spiro-OMeTAD, P3HT, TPAA, MeO-TPD, bis-EDOT, DEH, Li+ ion migration, charge recombination, electron lifetime
National Category
Chemical Sciences
urn:nbn:se:uu:diva-232271 (URN)978-91-554-9038-6 (ISBN)
Public defence
2014-10-31, Uppsala, 13:15 (English)
Available from: 2014-10-08 Created: 2014-09-16 Last updated: 2015-01-23Bibliographically approved

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Yang, LeiBi, DongqinTian, HainingBoschloo, GerritHagfeldt, AndersJohansson, Erik M. J.
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