Detailed analysis of transmission spectra and Bragg-reflection spectra of a two-dimensional photonic crystal with a lattice constant of 115 µm

Sakoda, Kazuaki; Sasada, M.; Fukushima, Tetsuya; Yamanaka, Akio; Kawai, Noriko; Inoue, Kuon

doi:10.1364/josab.16.000361

Cited by 25 publications

(16 citation statements)

References 13 publications

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“…The basic idea is the following: if photons could reside in the material for a longer time, then the interaction between matter and light would be enhanced. A photonic crystal is characterized by its dispersion band curve, i.e., light frequency ω versus wavevector k , of which the Bloch modes near the photonic bandgap edges are the focus here . In a photonic crystal of length L along the propagation direction, light travels in a Bloch mode with a lifetime τ given by:

1 / τ = V_{normalg} / L + α / (4 π) {(2 π / L)}^{2} + \dots,

where V g is the group velocity of light ( V g = dω/d k ) and α is the curvature of the Bloch mode dispersion curve (α = d 2 ω/ d k 2 ) .…”

Section: Photonic Crystals and Slow Photonsmentioning

confidence: 99%

Slow Photons for Photocatalysis and Photovoltaics

et al. 2017

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Solar light is widely recognized as one of the most valuable renewable energy sources for the future. However, the development of solar-energy technologies is severely hindered by poor energy-conversion efficiencies due to low optical-absorption coefficients and low quantum-conversion yield of current-generation materials. Huge efforts have been devoted to investigating new strategies to improve the utilization of solar energy. Different chemical and physical strategies have been used to extend the spectral range or increase the conversion efficiency of materials, leading to very promising results. However, these methods have now begun to reach their limits. What is therefore the next big concept that could efficiently be used to enhance light harvesting? Despite its discovery many years ago, with the potential for becoming a powerful tool for enhanced light harvesting, the slow-photon effect, a manifestation of light-propagation control due to photonic structures, has largely been overlooked. This review presents theoretical as well as experimental progress on this effect, revealing that the photoreactivity of materials can be dramatically enhanced by exploiting slow photons. It is predicted that successful implementation of this strategy may open a very promising avenue for a broad spectrum of light-energy-conversion technologies.

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1 / τ = V_{normalg} / L + α / (4 π) {(2 π / L)}^{2} + \dots,

where V g is the group velocity of light ( V g = dω/d k ) and α is the curvature of the Bloch mode dispersion curve (α = d 2 ω/ d k 2 ) .…”

Section: Photonic Crystals and Slow Photonsmentioning

confidence: 99%

Slow Photons for Photocatalysis and Photovoltaics

et al. 2017

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“…4 Thirdly, semiconductor QDs have the potential for multiple exciton generation (MEG), which can potentially increase the photovoltaic conversion efficiency up to 44%. 19 In addition, depending on the lling fraction of the TiO 2 , a photonic bandgap is formed in the photonic crystal, [34][35][36][37] which gives the possibility of enhancing the light harvesting efficiency. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] One of the main factors determining the photovoltaic performance of sensitized solar cells is the morphology of the TiO 2 electrodes, which has an effect on the sensitizer assembly and, consequently, the photovoltaic conversion efficiency.…”

Section: Introductionmentioning

confidence: 99%

Electronic structures of two types of TiO₂ electrodes: inverse opal and nanoparticulate cases

et al. 2015

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We present a comparison between the electronic structures of inverse opal (IO) and nanoparticulate (NP)-TiO 2 electrodes. The electronic structure details were obtained from optical absorption, fluorescence, and valence band studies in order to clarify the nature of the higher photovoltaic performance observed in sensitized solar cells using IO-TiO 2 electrodes. We used photoacoustic (PA) and photoluminescence (PL) spectroscopy to characterize the optical absorption and fluorescence properties, respectively.Photoelectron yield (PY) spectroscopy was applied to characterize the position of the valence band maximum (VBM) of the IO-and NP-TiO 2 electrodes. The PA spectrum for IO-TiO 2 is different to that for NP-TiO 2 , indicating differences in the exciton-phonon interactions and the density of states in the conduction band. PL measurements showed that the curvature of the valence band structure of IO-TiO 2 is different to that of NP-TiO 2 . Also, PL measurements showed that the oxygen vacancy in IO-TiO 2 is different to that in NP-TiO 2 . Moreover, PY measurements showed VBM in IO-TiO 2 to be at a higher position than that in NP-TiO 2 , suggesting a correlation with the increased open circuit voltage (V oc ) in sensitized solar cells.

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“…The inverse pattern containing a hexagonal array of air voids can be fabricated with the same mask by using a positive-tone photoresist. This pattern creates a template that should yield a PC with a mid-infrared ͑IR͒ band gap at approximately 5 m. 16 The band gap can be scaled towards the visible wavelength regime by reducing the dimensions of the grating and the wavelength of the laser.…”

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confidence: 99%

Fabrication of two-dimensional photonic crystals using interference lithography and electrodeposition of CdSe

Divliansky

Shishido

Khoo

et al. 2001

Applied Physics Letters

112

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This letter describes a simple synthetic approach to fabricate two-dimensional midinfrared CdSe photonic crystals ͑PC͒ by electrodeposition of CdSe in a polymer template defined using interference lithography. Characterization of the transmission spectra of CdSe PCs with a hexagonal array of 1.3 m diameter and 2.7 m pitch air voids showed a well-defined drop in transmission at 4.23 m. The drop in transmission increased with incident angle, reaching a maximum of approximately 2.6 dB at 40°relative to the surface normal. This two-step synthetic approach can be used to incorporate photonic crystals onto arbitrary substrates for integration into future advanced optical circuits.

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Detailed analysis of transmission spectra and Bragg-reflection spectra of a two-dimensional photonic crystal with a lattice constant of 115 µm

Cited by 25 publications

References 13 publications

Slow Photons for Photocatalysis and Photovoltaics

Slow Photons for Photocatalysis and Photovoltaics

Electronic structures of two types of TiO₂ electrodes: inverse opal and nanoparticulate cases

Fabrication of two-dimensional photonic crystals using interference lithography and electrodeposition of CdSe

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Detailed analysis of transmission spectra and Bragg-reflection spectra of a two-dimensional photonic crystal with a lattice constant of 115 µm

Cited by 25 publications

References 13 publications

Slow Photons for Photocatalysis and Photovoltaics

Slow Photons for Photocatalysis and Photovoltaics

Electronic structures of two types of TiO2 electrodes: inverse opal and nanoparticulate cases

Fabrication of two-dimensional photonic crystals using interference lithography and electrodeposition of CdSe

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Product

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Electronic structures of two types of TiO₂ electrodes: inverse opal and nanoparticulate cases