Wenqin Li

Wenqin Li; Yongzhen Wu; Xin Li; Yongshu Xie; Weihong Zhu

A novel series of organic dyes containing a fluorene unit as the conjunction bridge (S1–S4) have been designed and synthesized for a potential application in dye-sensitized solar cells (DSSCs). Their absorption spectra, electrochemical and photovoltaic properties have been investigated in detail. The tuning of the HOMO and LUMO energy levels can be conveniently realized by alternating the donor moiety. As demonstrated, the indoline unit can exhibit a stronger electron donating ability, realizing a broader absorption spectrum when coated onto TiO2. The incorporation of octyl-substituted fluorene is highly beneficial to prevent close π–π aggregation, thus favorably suppressing charge recombination and intermolecular interaction. In both the HOMO and LUMO orbitals, the electron density located at the conjunction bridge (fluorene unit) is quite low, suggesting that the incorporated fluorene unit plays quite a small role in the electron delocalization between the donor and acceptor units due to the twist conformation. The overall conversion efficiencies (η) of DSSCs based on these dyes are in the range of 3.04 to 4.26% and highly dependent upon their donor moiety. Among these dyes, S3, which utilizes a methyl-substituted indoline moiety as an electron donor, has shown a maximum monochromatic incident photon to current efficiency (IPCE) of almost 90%, with a relatively high open circuit voltage (Voc) of 727 mV.

Qipeng Chai; Wenqin Li; Jingchuan Liu; Zhiyuan Geng; He Tian; Weihong Zhu

Dye-sensitized solar cell (DSSC) is considered as a feasible route to the clean and renewable energy conversion technique. The commercial application requires further enhancements on photovoltaic efficiency and simplification on the device fabrication. For avoiding the unpreferable trade-off between photocurrent (JSC) and photovoltage (VOC), here we report the molecular engineering and comprehensive photovoltaic characterization of three cyclopentadithiophene-bridged D-A-π-A motif sensitizers with a change in donor group. We make a careful choice on the donor and conjugation bridge for synergistically increasing JSC and VOC. Comparing with the reference dye WS-2, the photovoltaic efficiency with the single component dye of WS-51 increases by 18%, among one of the rare examples in pure metal-free organic dyes exceeding 10% in combination with traditional iodine redox couples. Moreover, WS-51 exhibits several prominent merits on potentially scale-up industrial application: i) facile synthetic route to target molecule, ii) simple dipping procedure without requirement of co-sensitization, and iii) rapid dye adsorption capability.

Weihong Zhu; Yongzhen Wu; Shutao Wang; Wenqin Li; Xin Li; Jian Chen; Zhong-Sheng Wang; He Tian

Yongzhen Wu; Xi Zhang; Wenqin Li; Zhong-Sheng Wang; He Tian; Weihong Zhu

Wenqin Li; Yongzhen Wu; Qiong Zhang; He Tian; Weihong Zhu

Haibo Zhu; Wenqin Li; Yongzhen Wu; Bo Liu; Shiqin Zhu; Xin Li; Hans Ågren; Weihong Zhu

Qipeng Chai; Wenqin Li; Yongzhen Wu; Kai Pei; Jingchuan Liu; Zhiyuan Geng; He Tian; Weihong Zhu

Qipeng Chai; Wenqin Li; Shiqin Zhu; Qiong Zhang; Weihong Zhu

Weiwei Zhang; Wenqin Li; Yongzhen Wu; Jingchuan Liu; Xiongrong Song; He Tian; Weihong Zhu

Wenqin Li; Bo Liu; Yongzhen Wu; Shiqin Zhu; Qiong Zhang; Weihong Zhu