A theoretical design and investigation on Zn-porphyrin-polyoxometalate hybrids with different π-linkers for searching high performance sensitizers of p-type dye-sensitized solar cells

• Different connection mode leads to large difference on the performance of dyes.
• POM-porphyrin hybrid linked by naphthalenylethyne has strong charge transfer ability.
• The spectrum of hybrid with naphthalenylethyne overlaps well with the solar spectra.

Derived from an excellent sensitizer, Zn-porphyrin bearing phenylethynyl substituent, a series of Zn-porphyrin-polyoxometalate hybrids with different π-linkers were designed as sensitizers in p-type dye-sensitized solar cells. UV–vis spectra and charge transfer (CT) characters of studied hybrids were investigated by density functional theory (DFT) and time-dependent DFT methods to reveal the influence of π-linkers on sensitizers. The long π-linkers and high delocalization of systems 2–5 lead to the red shift and broadened absorption peak compared with system 1. CT analysis on the amount of transferred electrons (qCT), CT distance (dCT) and t index assessing the charge separation extent indicate that system 3 reaches the maximum CT and spatial charge separation. Furthermore, it performs a balance on light harvesting efficiency (LHE), hole injecting efficiency (HJE), dye regeneration efficiency (DRE) and charge recombination efficiency (CRE). Meanwhile, its spectrum well overlaps with the solar spectra. Therefore, system 3 would be a promising p-type sensitizer.

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