Zirconium(IV) and Hafnium(IV) Porphyrin and Phthalocyanine Complexes as New Dyes for Solar Cell Devices

Abstract

Metalloporphyrin and metallophthalocyanine dyes ligating Hf(IV) and Zr(IV) ions bind to semiconductor oxide surfaces such as TiO2 via the protruding group IV metal ions. The use of oxophylic metal ions with large ionic radii that protrude from the macrocycle is a unique mode of attaching chromophores to oxide surfaces in the design of dye-sensitized solar cells (DSSCs). Our previous report on the structure and physical properties of ternary complexes wherein the Hf(IV) and Zr(IV) ions are ligated to both a porphyrinoid and to a defect site on a polyoxometalate (POM) represents a model for this new way of binding dyes to oxide surfaces. The Zr(IV) and Hf(IV) complexes of 5,10,15,20-tetraphenylporphyrin (TPP) with two ligated acetates, (TPP)Hf(OAc)2 and (TPP)Zr(OAc)2, and the corresponding metallophthalocyanine (Pc) diacetate complexes, (Pc)Hf(OAc)2 and (Pc)Zr(OAc)2, were evaluated as novel dyes for the fabrication of dye-sensitized solar cells. Similarly to the ternary complexes with the POM, the oxide surface replaces the acetates to affect binding. In DSSCs the Zr(IV) phthalocyanine dye performs better than the Zr(IV) porphyrin dye, and reaches an overall efficiency of ~ 1.0%. The Hf(IV) dyes are less efficient. The photophysical properties of these complexes in solution suggested energetically favorable injection of electrons into the conduction band of TiO2 semiconductor nanoparticles, as well as a good band gap match with I3−/I− pair in liquid 1-butyl-3-methyl imidazolium iodide. The combination of blue absorbing TPP with the red absorbing Pc complexes can increase the absorbance of solar light in the device; however, the overall conversion efficiency of DSSCs using TiO2 nanoparticles treated with a mixture of both Zr(IV) complexes is comparable, but not greater than, the single (Pc)Zr. Thus, surface bound (TPP)Zr increases the absorbance in blue region of the spectra, but at the cost of diminished absorbance in the red in this DSSC architecture.

Self-Organization of Zr(IV) Porphyrinoids on Graphene Oxide Surfaces by Axial Metal Coordination

“…34 The UV-visible spectral shifts and decreased intensity in the Zr IV (Pc) Q band (676 nm) and Zr IV (TPP) Soret (421 nm) after incubation are consistent with displacement of the acetate ligands by the oxygen functional groups on the GO and formation of the hybrid material (Figure 3). 34 The intensity of the UV-visible spectra of the hybrid materials with Zr IV (Pc) or Zr IV (TPP) attached to GO monotonically decreases without changes in peak λ max as the solution is diluted, thus indicating that the solution is homogeneously dissolved and the zirconium dyes are strongly bound to the GO. Since the zinc species, Zn(Pc) and Zn(TPP), cannot accommodate further ligation and do not chemically bond GO, the electronic spectra are not altered upon addition of the GO dispersion.…”

Charge transfer dynamics at the boron subphthalocyanine chloride/C60 interface: non-adiabatic dynamics study with Libra-X

“…For these reasons, phthalocyanines and their derivatives have been attracting continuous interest as potential template chromophores that could be used in OPV materials. [19][20][21][22][23][24][25][26][27] Boron subphthalocyanine chloride (SubPc)/fullerene (C 60 ) heterojunctions have been recently attracting a lot of interest because of the high open-circuit voltages and power conversion efficiencies of such systems. [28][29][30][31][32][33][34] SubPc is composed of three nitrogen-fused diiminoisoindole rings that are connected around a boron atom and form a cone-shaped structure.…”

Self-Assembled Materials Incorporating Functional Porphyrins and Carbon Nanoplatforms as Building Blocks for Photovoltaic Energy Applications

“…The choice of materials is also practically unlimited, and specific parts of the solar spectrum can be selectively absorbed. Mimicking the natural light harvesting in photosynthesis, in which a number of chlorophylls and carotenoids are involved in light collection, suggests that it is likely that optimal photosensitisation in DSSCs will only occur using a mixture of dyes (Campbell et al, 2004;Radivojevic et al, 2012).…”