• Macromolecular Research
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• v.11 no.3
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• pp.133-145
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• 2003

We have developed novel lanthanide-cored supramolecular systems with highly efficient light-harvesting dendritic arrays for integrated planar waveguide-typed amplifiers. Er$^{3+}$ ions were encapsulated by the supramolecular ligands, such as porphyrins and macrobicyclics. The supramolecular ligands have been designed and synthesized to provide enough coordination sites for the formation of stable Er(III)-chelated complexes. For getting a higher optical amplification gain, also, the energy levels of the supramolecular ligands were tailored to maintain the effective energy transfer process from supramolecular ligands to erbium(III) ions. Furthermore, to maximize the light-harvesting effect, new aryl ether-functionalized dendrons as photon antennas have been incorporated into lanthanide-cored supramolecular systems. In this paper, molecular design, synthesis and luminescent properties of novel lanthanide-cored integrated supramolecular systems with highly efficient light-harvesting dendritic arrays will be discussed.d.

• Bulletin of the Korean Chemical Society
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• v.25 no.4
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• pp.443-444
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• 2004

• Macromolecular Research
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• v.15 no.3
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• pp.272-279
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• 2007

• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.343-344
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• 2004

• Journal of Electrochemical Science and Technology
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• v.1 no.2
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• pp.69-74
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• 2010

Methodologies to improve photovoltaic performance of dye-sensitized solar cell (DSSC) are reviewed. DSSC is usually composed of a dye-adsorbed $TiO_2$ photoanode, a tri-iodide/iodide redox electrolyte and a Pt counter electrode. Among the photovoltaic parameters of short-circuit photocurrent density, open-circuit voltage and fill factor, short-circuit photocurrent density is the collective measure of light harvesting, charge separation and charge collection efficiencies. Internal quantum efficiency is known to reach almost 100%, which indicates that charge separation occurs without loss by recombination. Thus, light harvesting efficiency plays an important role in improvement of photocurrent. In this paper, technologies to improve light harvesting efficiency, including surface area improvement by nano-dispersion, size-dependent light scattering efficiency, bi-functional nano material, panchromatic absorption by selective positioning of three different dyes and transparent conductive oxide (TCO)-less DSSC, are introduced.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.77.2-77.2
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• 2015

Recently, metamaterials attracted much attention because of the potential applications for superlens, cloaking and high precision sensors. We developed several dielectric metamaterials for enhancing antireflection or light trapping capability in solar energy harvesting devices. Colloidal lithography and electrochemical anodization process were employed to fabricate self-assembed nano- and microscale dielectric metamaterials in a simple and cost-effective manner. We improved broadband light absorption in c-Si, a-Si, and organic semiconductor layer by employing polystyrene (PS) islands integrated Si conical-frustum arrays, resonant PS nanosphere arrays, and diffusive alumina nanowire arrays, respectively. We also demonstrated thin metal coated alumina nanowire array which is utilized as an efficient light-to-heat conversion layer of solar steam generating devices. The scalable design and adaptable fabrication route to our light management nanostructures will be promising in applications of solar energy harvesting system. On the other hands, broadband invisible cloaks, which continuously work while elastically deforming, are developed using smart metamaterials made of photonic and elastic crystals. A self-adjustable, nearly lossless, and broadband (10-12GHz) smart meatamaterials have great potentials for applications in antenna system and military stealth technology.

• Journal of Photoscience
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• v.9 no.2
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• pp.359-361
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• 2002

A green mutant of Rhodobacter sphaeroides 60I was acquired by chemical induction. The blue-shifted of the carotenoid absorption was found in the Light-harvesting complex II (LH2) of the mutant. With the excitation at different wavelength, we observed that the evolution of excited-state dynamics in LH2 of Rhodobacter sphaeroides 60I. The dynamical traces demonstrate a dominant absorption followed concomitantly by an ultrafast transmission increase and decay with 818nm excitation.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1729-1730
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• 2006

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.117.1-117.1
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• 2011

We have demonstrated Forst-type resonance energy transfer (FRET) in the quasi-solid type dye-sensitized solar cells between organic fluorescence materials as an energy donor doped in polymeric gel electrolyte and ruthenium complex as an energy acceptor on surface of $TiO_2$. The strong spectral overlap of emission/absorption of energy donor and acceptor is required to get high FRET efficiency. The judicious choice of energy donor allows the enhancement of light harvesting characters of energy acceptor in quasi-solid dye sensitized solar cells which increase the power conversion efficiency. The enhanced light harvesting effect by the judicious choice/design of the fluorescence materials and sensitizing dyes permits the enhancement of photovoltaic performance of DSSC.

• Bulletin of the Korean Chemical Society
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• v.26 no.2
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• pp.201-214
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• 2005

We have designed and developed novel luminescent lanthanide complexes for advanced photonics applications. Lanthanide(III) ions (Ln$^{3+}$) were encapsulated by the luminescent ligands such as metalloporphyrins and naphthalenes. The energy levels of the luminescent ligands were tailored to maintain the effective energy transfer process from luminescent ligands to Ln$^{3+}$ ions for getting a higher optical amplification gain. Also, key parameters for emission enhancement and efficient energy transfer pathways for the sensitization of Ln$^{3+}$ ions by luminescent ligands were investigated. Furthermore, to enhance the optophysical properties of novel luminescent Ln$^{3+}$ complexes, aryl ether-functionalized dendrons as photon antennas have been incorporated into luminescent Ln$^{3+}$ complexes, yielding novel Ln(III)-cored dendrimer complex. The novel Ln(III)-cored dendrimer complex has much higher PL intensity than the corresponding simple complex, due to the efficient site-isolation effect. In this article, we will deal with recent progress in the synthesis and photophysical studies of inert and stable luminescent Ln$^{3+}$ complexes for advanced photonics applications. Also, our review will include the exploratory investigation of the key parameters for emission enhancement and the effective energy transfer pathways from luminescent ligands to Ln$^{3+}$ ions with Ln(III)-chelated prototype complexes.