Novel porphyrin-preparation, characterization, and applications in solar energy conversion. Issue 9 (16th February 2016)

• Record Type: Journal Article
• Authors: Lu, Jianfeng; Li, Hao; Liu, Shuangshuang; Chang, Yu-Cheng; Wu, Hui-Ping; Cheng, Yibing; Wei-Guang Diau, Eric; Wang, Mingkui
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 9(2016)
• Page Start: 6885
• Page End: 6892
• Publication Date: 2016-02-16
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c5cp05658f
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Accelerated inner charge transfer in porphyrins promotes a broad light-harvesting ability up to 840 nm and a conversion efficiency of 9.2%. Abstract : Porphyrins have been demonstrated as one of the most efficient sensitizers in dye-sensitized solar cells (DSSC). Herein, we investigated a series of porphyrin sensitizers functionalized with various π-spacers, such as phenyl for LD14, thiophene for LW4, thiophene–phenyl for LW5, and 2, 1, 3-benzothiadiazole (BTD)–phenyl for LW24. Photo-physical investigation by means of time-resolved fluorescence and nanosecond transient absorption spectroscopy revealed an accelerated inner charge transfer in porphyrins containing the BTD–phenyl π-spacer. Implementation of an auxiliary electron-deficient BTD unit to the porphyrin spacer also results in a broad light-harvesting ability extending up to 840 nm, contributing to an enhanced charge transfer character from the porphyrin ring to the anchoring group. When utilized as a sensitizer in DSSCs, the LW24 device achieved a power conversion efficiency of 9.2%, higher than those based on LD14 or LW5 porphyrins (PCE 9.0% or 8.2%, respectively) but lower than that of the LW4 device (PCE 9.5%). Measurements of transient photovoltage decays demonstrate that the LW24 device features the up-shifted potential band edge of the conduction band of TiO2, but involves serious charge recombination in the dye/TiO2 interface. The findings provide insights into the molecular structure and the charge-transfer characteristics for designing efficient porphyrin sensitizers for DSSC applications.