Titanium dioxide is a well-known material used in solar panels as a light absorbing semiconducting layer. Its absorbance peaks in the UV region, which is where TiO2 performs well as a light absorber. However, typical approximate solar energy distribution is as follows: 5% UV (300-400 nm), 43% visible (400-700 nm) and 52% near IR (700-2500 nm). It is obvious then that TiO2 harvests only a very small fraction of the solar energy. To increase the efficiency of the light harvesting, photosensitizers were developed. Porphyrins are a major first-generation class of compounds capable of photosensitization and are still in use due to their remarkable properties (stability, extremely high extinction coefficients and absorption of light over practically entire visible spectrum and beyond). Several free base and centrally metallated porphyrins were previously designed, synthesized and characterized, and provided excellent results. The research described here focuses on synthesis and characterization of a porphyrin centrally substituted with a non-metal, namely phosphorus (V) as a photosensitizer in TiO2 experimental solar cells. To the best of the authors’ knowledge, this is the first application of a diaxially substituted P(V) porphyrin, specifically, dichlorophosphorus(V)-meso-5,10,15,20-tetraphenylporphyrin chloride, or [P(V)Cl2-TPP]+ Cl-, for this particular purpose. The obtained results demonstrate a 31.4% boost in performance of experimental solar cells, delivered by the P(V) porphyrin photosensitizer in comparison to a non-photosensitized reference TiO2 cell. Experimentally determined photo voltages, photo currents and optimal concentration of the porphyrin in the coating solution are presented and discussed.

Diaxially substituted P(V) porphyrin as a new photosensitizer for TiO2-based solar cells

251st National Meeting (2016)

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