Enhanced Incident Photon-to-Electron Conversion Efficiency of Tungsten Trioxide Photoanodes Based on 3D-Photonic Crystal Design

Abstract

In this study, 3D-photonic crystal design was utilized to enhance incident photon-to-electron conversion efficiency (IPCE) of WO(3) photoanodes. Large-area and high-quality WO(3) photonic crystal photoanodes with inverse opal structure were prepared. The photonic stop-bands of these WO(3) photoanodes were tuned experimentally by variation of the pore size of inverse opal structures. It was found that when the red-edge of the photonic stop-band of WO(3) inverse opals overlapped with the WO(3) electronic absorption edge at E(g) = 2.6-2.8 eV, a maximum of 100% increase in photocurrent intensity was observed under visible light irradiation (λ > 400 nm) in comparison with a disordered porous WO(3) photoanode. When the red-edge of the stop-band was tuned well within the electronic absorption range of WO(3), noticeable but less amplitude of enhancement in the photocurrent intensity was observed. It was further shown that the spectral region with a selective IPCE enhancement of the WO(3) inverse opals exhibited a blue-shift in wavelength under off-normal incidence of light, in agreement with the calculated stop-band edge locations. The enhancement could be attributed to a longer photon-matter interaction length as a result of the slow-light effect at the photonic stop-band edge, thus leading to a remarkable improvement in the light-harvesting efficiency. The present method can provide a potential and promising approach to effectively utilize solar energy in visible-light-responsive photoanodes.

A colloidoscope of colloid-based porous materials and their uses

“…For example, it accounted for a >50% increase in the efficiency of a DSSC, 447 and can be seen clearly in Figure 30 for a photoanode made from WO 3 , where the efficiency varies as a function of wavelength depending on the periodicity of the structure. 393 There is a clear efficiency enhancement for the structure made with 200 nm colloids, which has a photonic bandgap overlapping with the electronic absorption of WO 3 . In addition to ordered structures for increased absorption of certain wavelengths, disordered structures can be used to increase scattering of all wavelengths, 71 which also improves absorption by increasing the path length in the structure.…”

Improving O2 production of WO3 photoanodes with IrO2 in acidic aqueous electrolyte

“…Tungsten trioxide, WO 3 , an earth-abundant, oxidatively stable semiconductor, is one such material that could fulfill the role of photoanode. [14][15][16][17][18][19][20][21][22][23][24] In most deposition methods, the presence of oxygen vacancies serve as shallow electron donors and naturally dope the WO 3 n-type. 25 Its band gap of 2.6 eV is higher than ideal for the large band gap absorber in a tandem cell.…”

Synthesis and characterization of tungstite (WO3·H2O) nanoleaves and nanoribbons

“…A simple heat-treatment of tungstite (WO 3 .H 2 O) allows for the phase transformation to tungsten oxide (WO 3 ), an important class of n-type semiconductors with a tunable band gap of 2.5-2.8 eV [16]. Moreover, its high chemical stability, low production costs and non-toxicity have recently generated significant interests for a wide variety of applications in microelectronics and optoelectronics [17][18], super-hydrophilic thin films [15], dye-sensitized solar cells [19], colloidal quantum dot LEDs [20], photocatalysis [21] and photoelectrocatalysis [22], water splitting photocatalyst as main catalyst [23][24][25][26][27][28][29][30][31][32][33][34]. Environmental applications can also benefit from WO 3 as a visible light photocatalyst to generate OH radicals for bacteria destruction [35] and photocatalytic reduction of CO 2 into hydrocarbon fuels [36].…”