Highly Asymmetrical Porphyrins with Enhanced Push–Pull Character for Dye‐Sensitized Solar Cells

Abstract

A porphyrin π-system has been modulated by enhancing the push-pull character with highly asymmetrical substitution for dye-sensitized solar cells for the first time. Namely, both two diarylamino moieties as a strong electron-donating group and one carboxyphenylethynyl moiety as a strong electron-withdrawing, anchoring group were introduced into the meso-positions of the porphyrin core in a lower symmetrical manner. As a result of the improved light-harvesting property as well as high electron distribution in the anchoring group of LUMO, a push-pull-enhanced, porphyrin-sensitized solar cell exhibited more than 10% power conversion efficiency, which exceeded that of a representative highly efficient porphyrin (i.e., YD2)-sensitized solar cell under optimized conditions. The rational molecular design concept based on highly asymmetric, push-pull substitution will open the possibilities of further improving cell performance in organic solar cells.

Interaction of YD2 and TiO2 in dye-sensitized solar cells (DSSCs): a density functional theory study

“…In particular, we focused on the vibrational frequency of the -COO − group. For the free dye, a vibrational frequency of 1665 cm −1 is obtained, which is close to the reported experimental value of 1700 cm −1 [28]. On the other hand, when YD2 is linked with TiO 2 , the vibrational frequency decreases to 1350 cm −1 , which is close to the experimental value of 1400 cm −1 .…”

“…Depending on the dye, mono-or bidentate coordination is observed [42][43][44][45]. With respect to the -COO − group, it is well known that the experimental IR spectrum exhibits a significant increase in the symmetric carboxylate band at around 1400 cm −1 [28]. The disappearance of this C=O frequency confirms that a proton detaches from the carboxylic acid group during porphyrin adsorption on TiO 2 .…”

“…The resulting highly efficient DSSCs have good photostability and light-harvesting capabilities, with η values of about 6-10 %, close to those of DSSCs with dyes based on ruthenium complexes [13]. Among the most efficient of these Zn-based dyes are YD2, YD2-o-C8, ZnPBAT, and LD14 [27,28].…”

Charge recombination losses in thiophene-substituted porphyrin dye-sensitized solar cells

“…In this type of solar cell the properties of the dye, such as colour, molecular extinction coeffi-cient and robustness under illumination, are of utmost importance. Among the examples of dyes published in the literature [3] for Gratzel€ solar cells, porphyrins [4] have pleasant colours [5], excel-lent molecular extinction coefficients [6,7] and good robustness [8,9]. Moreover, based on the work of Yella and co-workers [1], efficiencies that surpass the values obtained with ruthenium sen-sitizers have been achieved.…”

Supramolecular arrangements of an organometallic forming nanostructured films

“…Dther important characteristic of the porphyrins is the ability to transfer oxygen and electrons. This ability comes from their intense Soret and moderate Q bands allowing to collect visible light efficiently in the light-harvesting process 10 and thus make them promising for use in solar energy conversion [10][11][12] and in light harvesting [13][14][15] . Most applications involving porphyrins and their derivatives are related to devices such as catalysts [16][17][18] and sensors [19][20][21][22][23][24] .…”