Efficient Dye-Sensitized Solar Cells with an Organic Photosensitizer Featuring Orderly Conjugated Ethylenedioxythiophene and Dithienosilole Blocks

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• 作者：Wangdong Zeng ; Yiming Cao ; Yu Bai ; Yinghui Wang ; Yushuai Shi ; Min Zhang ; Fangfang Wang ; Chunyue Pan ; Peng Wang
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：March 9, 2010
• 年：2010
• 卷：22
• 期：5
• 页码：1915-1925
• 全文大小：1018K
• 年卷期：v.22,no.5(March 9, 2010)
• ISSN：1520-5002

文摘

In view of the limited ruthenium resource, metal-free organic dyes may play a prominent role in the coming large-scale application of cost-effective dye-sensitized solar cells, if their efficiency and stability can be considerably improved. In this paper we utilized a binary π-conjugated spacer of ethylenedioxythiophene and dithienosilole to construct a high molar absorption coefficient push−pull dye, characteristic of an intramolecular charge-transfer band peaking at 584 nm measured in chloroform. In comparison with the standard ruthenium sensitizer Z907, this metal-free chromophore C219 endowed a nanocrystalline titania film with an evident light-harvesting enhancement, leading to an unprecedented 10.0−10.3% efficiency at the AM1.5G conditions for dye-sensitized solar cells with nonruthenium dyestuffs, although a highly volatile electrolyte was used. Transient absorption measurements have revealed that even if the kinetics of back-electron transfer and dye regeneration are considerably different for Z907 and C219, the branching ratios of these two charge-transfer channels are over 35 for both dyes, ensuring a high yield of net charge separation at the titania/dye/electrolyte interface. A solvent-free ionic liquid cell with C219 as the sensitizer exhibited an impressive efficiency of 8.9% under a low light intensity of 14.39 mW cm⁻², making it very favorable for the indoor application of flexible dye-sensitized solar cells.