• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.89.2-89.2
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• 2010

The dye-sensitized solar cell (DSSC) is a device for the conversion of visible light into electricity, based on the sensitization of wide bandgap semiconductors. The performance of the cell mainly depends on a dye used as sensitizer. The absorption spectrum of the dye and the anchorage of the dye to the surface of $TiO_2$ are important parameters determining the efficiency of the cell. Generally, transition metal coordination compounds(ruthenium polypyridyl complexes) are used as the effective sensitizers, due to their intense charge-transfer absorption in the whole visible range and highly efficient metal-to ligand charge transfer. However, ruthenium polypyridyl complexes contain a heavy metal, which is undesirable from point of view of the environmental aspects. Moreover, the process to synthesize the complexes is complicated and costly. Alternatively, organic dyes can be used for the same purpose with an acceptable efficiency. The advantages of organic dyes include their availability and low cost. We designed and synthesized a series of organic sensitizers containing long wavelength absorption-chromophores for the dye sensitized solar cell. The DSSC composed of Blue-chromophores for the sensitization absorbed long wavelength region which is different also applied into the dye-cocktail (mixing) system. The photovoltaic property of DSSCs organic long wavelength absorption-chromophores were measured and evaluated by comparison with that of individual chromophores.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.118.1-118.1
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• 2011

The dye-sensitized solar cell (DSSC) is a device for the conversion of visible light into electricity, based on the sensitization of wide bandgap semiconductors. The performance of the cell mainly depends on a dye used as sensitizer. The absorption spectrum of the dye and the anchorage of the dye to the surface of TiO2 are important parameters determining the efficiency of the cell. Generally, transition metal coordination compounds(ruthenium polypyridyl complexes) are used as the effective sensitizers, due to their intense charge-transfer absorption in the whole visible range and highly efficient metal-to ligand charge transfer. However, ruthenium polypyridyl complexes contain a heavy metal, which is undesirable from point of view of the environmental aspects. Moreover, the process to synthesize the complexes is complicated and costly. Alternatively, organic dyes can be used for the same purpose with an acceptable efficiency. The advantages of organic dyes include their availability and low cost. We designed and synthesized a series of organic sensitizers containing long wavelength absorption-chromophores for the dye sensitized solar cell. The DSSC composed of Blue-chromophores for the sensitization absorbed long wavelength region which is different also applied into the dye-cocktail (mixing) system. The photovoltaic property of DSSCs organic long wavelength absorption-chromophores were measured and evaluated by comparison with that of individual chromophores.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1712-1714
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• 2004

During the last 20 years organic semiconductors have attracted considerable attention due to their interesting physical properties followed by various technological applications in the area of electronics and opto-electronics. It has been a long time since organic solar cells were expected as a low-cost energy-conversion device. Although practical use of them has not been achieved, technological progress continues. Morphology of the materials, organic/inorganic interface, metal cathodes, molecular packing and structural properties of the donor and acceptor layers are essential for photovoltaic response. We have fabricated solar cell devices based on zinc-phthalocyanine(ZnPc) as donor(D) and fullerine($C_{60}$) as electron acceptor(A) with doped charge transport layers, $Alq_3$ as an electron transport or injection layer. We observed the photovoltaic characteristics of the solar cell devices using the Xe lamp as a light source.

• Transactions on Electrical and Electronic Materials
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• v.6 no.3
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• pp.124-127
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• 2005

It has been a long time since organic solar cells were expected as a low-cost energy-conversion device. Although practical use of them has not been achieved, technological progress continues. Morphology of the materials, organic/inorganic interface, metal cathodes, molecular packing and structural properties of the donor and acceptor layers are essential for photovoltaic response. We have fabricated solar cell devices based on zinc-phthalocyanine(ZnPc) as donor(D) and fullerene$(C_60)$ as electron acceptor(A) with doped charge transport layers, and BCP and $Alq_3$ as an exciton blocking layer(EBL). We have measured the photovoltaic characteristics of the solar cell devices using the Xe lamp as a light source. We were use of $Alq_3$ layer leads to external power conversion efficiency was $2.65\%$ at illumination intensity $100\;mW/cm^2$. Also we confirmed the optimum thickness ratio of the DA hetero-junction is about 1:2.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.134.2-134.2
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• 2014

Photonic crystal solar cells have the potential for addressing the disparate length scales in polymer photovoltaic materials, thereby confronting the major challenge in solar cell technology: efficiency. One must achieve simultaneously an efficient absorption of photons with effective carrier extraction. Unfortunately the two processes have opposing requirements. Efficient absorption of light calls for thicker PV active layers whereas carrier transport always benefits from thinner ones, and this dichotomy is at the heart of an efficiency/cost conundrum that has kept solar energy expensive relative to fossil fuels. This dichotomy persists over the entire solar spectrum but increasingly so near a semiconductor's band edge where absorption is weak. We report a 2-D, photonic crystal morphology that enhances the efficiency of organic photovoltaic cells relative to conventional planar cells. The morphology is developed by patterning an organic photoactive bulk heterojunction blend of Poly(3-(2-methyl-2-hexylcarboxylate) thiophene-co-thiophene) and PCBM via PRINT, a nano-embossing method that lends itself to large area fabrication of nanostructures. The photonic crystal cell morphology increases photocurrents generally, and particularly through the excitation of resonant modes near the band edge of the organic PV material. The device performance of the photonic crystal cell showed a nearly doubled increase in efficiency relative to conventional planar cell designs. Photonic crystals can also enhance performance of other optoelectronic devices including organic laser.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.97-97
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• 2010

We demonstrate the hybrid polymer-quantum dot based multi-functional device (Organic bistable devices, Light-emitting diode, and Photovoltaic cell) with a single active-layer structure consisting of CdSe/ZnS semiconductor quantum-dots (QDs) dispersed in a poly N-vinylcarbazole (PVK) and 1,3,5-tirs- (N-phenylbenzimidazol-2-yl) benzene (TPBi) fabricated on indium-tin-oxide (ITO)/glass substrate by using a simple spin coating technique. The multi-functionality of the device as Organic bistable device (OBD), Light Emitting Diode (LED), and Photovoltaic cell can be successfully achieved by adding an electron transport layer (ETL) TPBi to OBD for attaining the functions of LED and Photovoltaic cell in which the lowest unoccupied molecular orbital (LUMO) level of TPBi is positioned at the energy level between the conduction band of CdSe/ZnS and LiF/Al electrode (band-gap engineering). Through transmission electron microscopy (TEM) study, the active layer of the device has a p-i-n structure of a consolidated core-shell structure in which semiconductor QDs are uniformly and isotropically adsorbed on the surface of a p-type polymer core and the n-type small molecular organic materials surround the semiconductor QDs.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.311-312
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• 2010

The fabricated photovoltaic cells based on PIN heterojunctions, in this study, have a structure of ITO/poly(3, 4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)/donor/donor:C60(10nm)/C60(35nm)/2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline(8nm)/Al(100nm). The thicknesses of an active layer(donor:C60), an electron transport layer(C60), and hole/exciton blocking layer(BCP) were fixed in the organic photovoltaic cells. We investigated the performance characteristics of the PIN organic photovoltaic cells with copper phthalocyanine(CuPc), tetracene and pentacene as a hole transport layer. Discussion on the photovoltaic cells with CuPc, tetracene and pentacene as a hole transport layer is focussed on the dependency of the power conversion efficiency on the deposition rate and thickness of hole transport layer. The device performance characteristics are elucidated from open-circuit-voltage(Voc), short-circuit-current(Jsc), fill factor(FF), and power conversion efficiency($\eta$). As the deposition rate of donor is reduced, the power conversion efficiency is enhanced by increased short-circuit-current(Jsc). The CuPc-based PIN photovoltaic cell has the limited dependency of power conversion efficiency on the thickness of hole transport layer because of relatively short exciton diffusion length. The photovoltaic cell using tetracene as a hole transport layer, which has relatively long diffusion length, has low efficiency. The maximum power conversion efficiencies of CuPc, tetracene, and pentacene-based photovoltaic cells with optimized deposition rate and thickness of hole transport layer have been achieved to 1.63%, 1.33% and 2.15%, respectively. The photovoltaic cell using pentacene as a hole transport layer showed the highest efficiency because of dramatically enhanced Jsc due to long diffusion length and strong thickness dependence.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.356-357
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• 2003

Organic materials are suitable for use in photoelectric conversion devices. Thus, Organic semiconductors are promising materials for photovoltaic devices and other optoelectronic applications such as light emitting diodes(LED). The organic solar cell seems to be the usefulness in comparison with the inorganic solar cell in terms of workability, ease of processing, low cost, flexibility and area expansion. (omitted)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.36-36
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• 2010

Currently, there are several newly developed energy resources for the future to replace petroleum resources such as hydrogen fuel cell, solar cell, wind power, and etc. Among them, solar cell has attracted a worldwide concern, because it has an enormous amount of resources. In general, a study of solar cells can be classified in to an area of bulk type and thin-film type. Inorganic solar cells based on silicon have been tremendously developed in technology and efficiency. However, since there are many lithographic steps, high processing temperature approximately $1000^{\circ}C$, and expensive raw materials, a manufacturing cost of device are nearly reaching a limit. Contrary to those disadvantages, organic solar cells can be manufactured at room temperature. Also, it has many advantages such as a low cost, easy fabrication of thin film, and possible manufacture to a large size. Because it can be made to be flexible, research and development on solar cells are actively in progress for the next generation. ever though an efficiency of the organic solar cell is low compared to that of inorganic one, a continuous study is needed. In this paper, we report optimal device structure obtained by a program simulation for design and development of highly efficient organic photovoltaic cells. we have also compared simulated results to experimental ones.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1463-1464
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• 2011

An indium thin oxide(ITO) is used as a substrate material for organic light-emitting diodes(OLEDs) and organic photovoltaic cells. This study examined the effects of an $O_2$ plasma treatment on the electrical properties of an organic photovoltaic cell. The four probe method and Atomic force microscope(AFM) revealed the lowest surface resistance at the plasma treatment intensity of 250 [W] and the lowest average surface roughness of 2.0 [nm] at 250 [W]. The lowest average resistance of 17 [${\Omega}$/sq] was also observed at 250 [W] 40 [sec]. The $O_2$ plasma treatment device and a basic device in a structure of CuPc/C60/BCP/Al on ITO glass were fabricated by thermal evaporation, respectively. When the $O_2$ plasma treatment was used to the ITO, The experimental results revealed that the power conversion efficiency(PCE) indicated 65 [%] higher in the PCE than that without the plasma treatment.