Co-sensitization promoted light harvesting for organic dye-sensitized solar cells using unsymmetrical squaraine dye and novel pyrenoimidazole-based dye

• Published in: Journal of power sources 2013-10, Vol.240, p.779-785
• Main Authors: Chang, Jeffrey, Lee, Chuan-Pei, Kumar, Dhirendra, Chen, Ping-Wei, Lin, Lu-Yin, Thomas, K.R. Justin, Ho, Kuo-Chuan
• Format: Article
• Language: English
• Subjects: Applied sciences; Co-adsorbate; Co-sensitization; Dye-sensitized solar cell; Energy; Exact sciences and technology; Natural energy; Organic dyes; Photovoltaic conversion; Solar cells. Photoelectrochemical cells; Solar energy
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2013.04.075

The pure organic dyes are investigated recently because of its high extinction coefficient and relatively low cost. In order to enhance the performance of the organic dyes, co-sensitization strategy is applied. The co-sensitization by the absorption of SQ2/5c shows enhanced photovoltaic performance for the pertinent DSSCs, which leads to a broader light harvesting window (400–750 nm) and a higher overall efficiency of 6.24% while the performances of DSSCs with the individual dyes are 5.33% (5c) and 3.98% (SQ2), respectively. Furthermore, the overall efficiency can be further improved to 6.71% with the incorporation of chenodeoxycholic acid (CDCA). In addition, the incident photon-to-current conversion efficiency (IPCE) and UV–visible absorption spectra are also used to explain and support the behavior of the co-sensitized solar cells. The investigation of the long-term stability of the DSSC based on co-sensitization of SQ2/5c dyes with the use of binary ionic liquid is performed. The DSSC with the co-sensitization strategy possesses an unfailing durability up to 1000 h. [Display omitted] •A novel organic dye, 5c, is used with the SQ2 dye for co-sensitizing DSSC.•The co-sensitized dyes, SQ2/5c, have complementary absorption window.•Higher efficiencies of the co-sensitized DSSCs are achieved by adding CDCA.•A high efficiency of 6.70% is achieved for the co-sensitized DSSC under 1 sun.•The DSSC with the co-sensitized dyes of SQ2/5c shows durability up to 1000 h.