Standing Wave Enhancement of Red Absorbance and Photocurrent in Dye-Sensitized Titanium Dioxide Photoelectrodes Coupled to Photonic Crystals

Abstract

The light harvesting efficiency of dye-sensitized photoelectrodes was enhanced by coupling a TiO(2) photonic crystal layer to a conventional film of TiO(2) nanoparticles. In addition to acting as a dielectric mirror, the inverse opal photonic crystal caused a significant change in dye absorbance which depended on the position of the stop band. Absorbance was suppressed at wavelengths shorter than the stop band maximum and was enhanced at longer wavelengths. This effect arises from the slow group velocity of light in the vicinity of the stop band, and the consequent localization of light intensity in the voids (to the blue) or in the dye-sensitized TiO(2) (to the red) portions of the photonic crystal. By coupling a photonic crystal to a film of TiO(2) nanoparticles, the short circuit photocurrent efficiency across the visible spectrum (400-750 nm) could be increased by about 26%, relative to an ordinary dye-sensitized nanocrystalline TiO(2) photoelectrode.

Full spectrum enhancement of the light harvesting efficiency of dye sensitized solar cells by including colloidal photonic crystal multilayers

“…Some attempts in this line were performed adding polydisperse TiO 2 particles at the dye sensitized nc-TiO 2 layer. One step forward in this same direction but applying a different concept was given recently by Nishimura et al, 9 who built the dye sensitized nc-TiO 2 coating within a Grätzel solar cell in the form of a bilayer: One layer with the shape of a highly scattering photonic crystal ͑PhC͒ structure, i.e., an inverse TiO 2 opal; the other presents the form of a standard unstructured dyed nanocrystalline titania. This combined structure showed an enhancement of the photogenerated current efficiency of 26% when compared to a standard DSSC.…”

“…The number of close packed sphere monolayers composing the PhCs is arbitrarily fixed at 17 ML ͑ML denotes monolayer͒, which is the thickness of the colloidal lattice grown in Ref. 9. Finally, the whole system is soaked in the TG 50 electrolyte, whose refractive index is 1.433.…”

“…10 As starting point, and in order to fix some relevant parameters, we have simulated the spectral response of the LHE of the dye sensitized solar cell described in Ref. 9, with some changes in the order of the components to maximize the efficiency. In Fig.…”

Sandwich-structured TiO2 inverse opal circulates slow photons for tremendous improvement in solar energy conversion efficiency

“…[18][19][20] By matching the red or blue edge of photonic stopbands with the electronic excitation energy of the material, more than 2 fold enhancement of photocatalytic efficiency of TiO 2 has been demonstrated. [21][22][23][24][25][26] But, have we reached the limit of PC's amplification function in photochemistry? Can the effective optical path length of the 'slow photons' be further extended?…”

A versatile salicylic acid precursor method for preparing titanate microspheres

“…Inverse opalphotonic crystals assembled from microspheres are regarded as a bridge connecting artificial and natural materials. Such materials are utilized in chemical sensing, solar cells, and biosensing [10][11][12] applications. Microspherical materials have been demonstrated as key materials in energy and environment applications.…”