Redox couple related influences of bulky electron donor as well as spacer in organic dye-sensitized mesoscopic solar cells

For dye-sensitized solar cells (DSCs), it is of great significance to understand the structure-performance relationship of photosensitizers. Herein, we scrutinize the influences of the arylamine electron donors as well as the fused thiophene spacer on the optoelectronic features of thin-film DSCs employing the tris(1,10-phenanthroline)cobalt(II/III) or the iodide/triiodide redox couple. Interestingly, the incorporation of bulky dihexyloxybenzene-substituted triphenylamine (DHOB-TPA) electron donor does not resulted in an improved electron lifetime, which is sharp contrast with the conventional concept on bulky electron donor. On the other hand, the introduction of the DHOB-TPA electron donor or the dithienopyrrole spacer significantly increases the molar absorption coefficients of dyes, which govern the performance of thin-film DSCs. This work demonstrates how organic dyes must be tailored carefully depending on the electrolyte red/ox couple used.

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