• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.60.2-60.2
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• 2010

A $TiO_2$ films in dye-sensitized solar cells was fabricated using $TiO_2$ colloidal sol prepared from titanium iso-propoxide used as a starting material by applying the sol-gel method. It was characterized by particle size analyzer, XRD, FE-SEM, and BET analysis. The adsorption isotherms of dye molecule on $TiO_2$ films were obtained at three different temperatures (30, 45, $60^{\circ}C$) and at three different pH (3, 5, 7). The adsorption kinetics of dye molecule on $TiO_2$ films were obtained at three different temperatures (30, 45, $60^{\circ}C$. The adsorption experimental data were correlated with Langmuir isotherm model and pseudo-second-order model. Also the isosteric enthalpies of dye adsorption were calculated by the Clausius-Clapeyron equation. In addition, the adsorption energy distribution functions which describe heterogeneous characteristics of nanocrystalline $TiO_2$ film surface were calculated by using the generalized nonlinear regularization method. We found that efficient adsorption of N719 dye from aqueous solution onto $TiO_2$ films can be successfully achieved by dye adsorption conditions and morphology of $TiO_2$ films.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.12.1-12.1
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• 2010

We have developed a facile method to position different dyes (N719 and N749) sequentially in a mesoporous TiO2 layer through selective desorption and adsorption processes. Only upper part of the first adsorbed N719 dye was selectively removed by the desorption solution formulated with polypropylene glycol and tetrabutylammonium hydroxide without any damages of the dye. The desorption depth was controlled by the number of desorption process. Multi-dyed dye-sensitized solar cells (MDSSC) were fabricated by utilizing the method and their photovoltaic properties were investigated. From the incident photon-to-current conversion efficiency (IPCE) measurement, it was found that the MDSSC exhibited the extended spectral response for the solar spectrum while without decrease of maximum IPCE value compare to the DSSCs using one kind of dye (N719 or N749). The highest photocurrent density of 19.3 mA/cm2 was obtained from the MDSSC utilizing $15\;{\mu}m$ N719 / $14\;{\mu}m$ N749 bi-layered mesoporous TiO2 film. The photocurrent density was 25% and 8% higher than that of the DSSC using only N719 and N749 dye as a sensitizer, respectively. The power conversion efficiency of 9.8% was achieved from the MDSSC under the AM 1.5G one sun illumination.

• 대한화학회지
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• 제55권2호
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• pp.279-282
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• 2011

염료감을 태양전지(DSSC)는 대체에너지 집적제로서 낮은 생산단가로 고에너지 전환 효과를 볼 수 있다. 친환경적이며 효과가 큰 무금속 염료감응제의 개발이 중요하다. 본 연구에서 유기 감광제로 6,6'-(1,2,5-oxadiazole-3,4-diyl)dipyridine-2,4-dicarboxylic acid(3A)을 합성하였다. 이 감광제를 사용하여 광전환효율(${\eta}$)이 1.00%를 달성함을 발견하였다. 같은 조건에서 루테늄착물(N719)은 4.02%의 광전환효율을 나타내었다.

• 반도체디스플레이기술학회지
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• 제10권2호
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• pp.65-71
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• 2011

Properties of each layer in DSSC were investigated to improve solar cell characterstics. Also in this study, low costsolar simulator system is fabricated and used. Efficiency of DSSC is better in the case of thinner semiconductive layer, because thick semiconductive layer is acted as resistor. Sc-doped ZnO thin films showed better electrical property by proper donor doping effect. Among the dyes, DSSC containing N719 showed higher efficiency, because N719 have smaller electron affinity and shallow band gap.

• 한국전기전자재료학회논문지
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• 제26권3호
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• pp.252-256
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• 2013

We introduced sensitizing dyes into the bulk-heterojunction (BHJ) photovoltaic (PV) layer of polymer solar cells (PSCs). The sensitizing dyes doped were Bis(tetra butyl ammonium) cis-dithio cyanato bis(2,2'-bipyridine-4-carboxylicacid-4'-carboxylate) ruthenium (II) (N719 dye) and the BHJ PV layer used was made of poly (3-hexylthiophene) (P3HT) and phenyl $C_{61}$-butyric acid methyl ester (PCBM). It was found that the N719 dyes increase the photovoltaic performance, i.e., increasing open-circuit voltage and short-circuit current density with improved fill factor. For the P3HT:PCBM PV cells doped with the N719 dyes (0.24 wt%), an increase in power conversion efficiency of 4.0% was achieved, compared to that of the control cells (3.6%) without the N719 dyes.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2011년도 춘계학술논문집 2부
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• pp.836-839
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• 2011

염료감응형 태양전지의 상대전극으로 MWCNT(multi-walled carbon nanotube)의 농도 (0.01~0.06g)를 달리하여 FTO(fluorine-doped tin oxide) glass에 분산시켜 상대전극을 만들었다. 그리고 glass/FTO/$TiO_2$/Dye(N719)/electrolyte(C6DMII,GSCN)/MWCNT/FTO/glass 구조를 가진 0.45$cm^2$급 DSSC(dye-sensitized solar cells) 소자를 만들었다. 소자의 미세구조, 분산정도, 광특성은 각각 광학현미경, SEM, source measure unit (Keithley model 2400) 장비를 이용하여 확인하였다. MWCNT 농도 증가와 FTO의 거친 표면형상에 따라 비선형적으로 MWCNT 분산면적이 증가하였고, MWCNT 농도 0.06g일 때 FTO 표면에 전체적으로 MWCNT가 완전히 분산됨을 확인하였다. 소자의 광변환 효율은 MWCNT 분산면적에 비례하는 효율을 보였고, MWCNT 분산농도인 0.06g 일 때 4.49%의 광변환 효율을 얻을 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.241-241
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• 2010

Recently high and persistent spontaneous buildup of a surface potential (SP) upon vacuum deposition of tris (8-hydroxyquinolinato) aluminum (III) ($Alq_3$), which is widely used for organic light emitting devices. The removal of the giant surface potential by visible light irradiation has also been reported. In this study, we coated $Alq_3$ on the FTO substrate and raise the capacity for absorbing sun light. The $Alq_3$ which is green light emitting diode emits light at wavelengths between 500 and 550nm. If we apply one's FTO/$Alq_3$ substrate in one's DSSC, we could get higher energy conversion efficiency because the N719 dye that we used for fabricating the DSSC emits light just at near 540nm. The energy conversion efficiency of approximately 4.8 % at the condition of irradiation of AM 1.5 (100 mW/$cm^2$) simulated sunlight, and the $J_{sc}$ is 12.0 mA/$cm^2$, $V_{oc}$ is 0.71 V, FF is 0.56, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.89.1-89.1
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• 2010

Since Gratzel and co-workers developed a new type of solar cell based on the nanocrystalline $TiO_2$ electrode, dye-sensitized solar cells (DSSCs) have attracted considerable attention on account of their high solar energy-to-conversion efficiencies (11%), their easy manufacturing process with low cost production compared to conventional p-n junction solar cells. The mechanism of DSSC is based on the injection of electrons from the photoexcited dye into the conduction band of nanocrystalline $TiO_2$. The oxidized dye is reduced by the hole injection process from either the hole counter or electrolyte. Thus, the electronic structures, such as HOMO, LUMO, and HOMO-LUMO gap, of dye molecule in DSSC are deeply related to the electron transfer by photoexcitation and redox potential. To date, high performance and good stability of DSSC based on Ru-dyes as a photosensitizer had been widely addressed in the literatures. DSSC with Ru-bipyridyl complexes (N3 and N719), and the black ruthenium dye have achieved power conversion efficiencies up to 11.2% and 10.4%, respectively. However, the Ru-dyes are facing the problem of manufacturing costs and environmental issues. In order to obtain even cheaper photosensitizers for DSSC, metal-free organic photosensitizers are strongly desired. Metal-free organic dyes offer superior molar extinction coefficients, low cost, and a diversity of molecular structures, compared to conventional Ru-dyes. Recently, novel photosensitizers such as coumarin, merocyanine, cyanine, indoline, hemicyanine, triphenylamine, dialkylaniline, bis(dimethylfluorenyl)-aminophenyl, phenothiazine, tetrahydroquinoline, and carbazole based dyes have achieved solar-to-electrical power conversion efficiencies up to 5-9%. On the other hand, organic dye molecules have large ${\pi}$-conjugated planner structures which would bring out strong molecular stacking in their solid-state and poor solubility in their media. It was well known that the molecular stacking of organic dyes could reduce the electron transfer pathway in opto-electronic devices, significantly. In this paper, we have studied on synthesis and characterization of dendritic organic dyes with different number of electron acceptor/anchoring moieties in the end of dendrimer. The photovoltaic performances and the incident photon-to-current (IPCE) of these dyes were measured to evaluate the effects of the dendritic strucuture on the open-circuit voltage and the short-circuit current.

• 한국산학기술학회논문지
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• 제15권6호
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• pp.4013-4018
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• 2014

염료감응형 태양전지 상대전극부에 Au/Pt 이중 촉매층 적용에 따른 전해질과의 반응안정성 확인과 에너지변환효율 변화를 확인하기 위해 $0.45cm^2$ 면적을 가진 glass/FTO/blocking layer/$TiO_2$/dye/electrolyte/50nm Pt/50nm Au/glass 구조의 소자를 준비하였다. 비교를 위해 평탄한 유리기판 위에 증착된 100nm 두께의 Pt 상대전극을 채용한 소자도 동일한 방법으로 확인하였다. 솔라 시뮬레이터와 퍼텐쇼 스탯을 통해 단락전류밀도, 개방전압, 필팩터, 에너지변환효율의 광전기적 특성을 확인하였다. Au/Pt 이중층과 전해질의 반응을 확인하기 위해 광학현미경을 통해 전해질 주입 후 0~25분 후 이중층의 미세구조를 확인하였다. 광전기적 특성 분석 결과, 평탄한 유리기판 위의 단일층 Pt의 에너지변환효율은 4.60%를 나타내고 시간 의존성이 없었다. 반면, Au/Pt의 경우 전해질 주입 직 후, 5분 후, 25분 후의 에너지 변환 효율이 각각 5.28%, 3.64%, 2.09%로 시간이 지남에 따라 감소하였다. 광학현미경 분석을 통하여, 전해질 주입 직 후, 5분 후, 25분 후의 부식면적이 각각 0, 21.92, 34.06%로 Au와 전해질이 반응하여 부식되는 것을 확인하였고, 이를 통해 Au/Pt가 전기적으로 시간이 지남에 따라 촉매활성도와 효율이 감소하는 것을 확인하였다. 따라서 염료감응태양전지에 Au/Pt 촉매는 단기적으로는 기존 Pt only보다 우수하였으나 장기적으로는 전해질과의 안정성이 미흡함을 확인하였다.

• 한국재료학회지
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• 제20권9호
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• pp.483-487
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• 2010

To fabricate $TiO_2$ nanoparticle-based dye sensitized solar cells (DSSCs) at a low-temperature, DSSCs were fabricated using hydropolymer and ZnO nanoparticles composites for the electron transport layer around a low-temperature ($200^{\circ}C$). ZnO nanoparticle with 20 nm and 60 nm diameter were used and Pt was deposited as a counter electrode on ITO/glass using an RF magnetron sputtering. We investigate the effect of ZnO nanoparticle concentration in hydropolymer and ZnO nanoparticle solution on the photoconversion performance of the low temperature fabricated ($200^{\circ}C$) DSSCs. Using cis-bis(isothiocyanato)bis(2,20 bipyridy1-4,40 dicarboxylato) ruthenium (II) bis-tetrabutylammonium (N719) dye as a sensitizer, the corresponding device performance and photo-physical characteristics are investigated through conventional physical characterization techniques. The effect of thickness of the ZnO photoelectrode and the morphology of the ZnO nanoparticles with the variations of hydropolymer to ZnO ratio on the photoconversion performance are also investigated. The morphology of the ZnO layer after sintering was examined using a field emission scanning electron microscope (FE-SEM). 60 nm ZnO nanoparticle DSSCs showed an incident photon-to-current conversion efficiency (IPCE) value of about 7% higher than that of 20 nm ZnO nanoparticle DSSCs. The maximum parameters of the short circuit current density ($J_{sc}$), the open circuit potential ($V_{oc}$), fill factor (ff), and efficiency ($\eta$) in the 60 nm ZnO nanoparticle-based DSSC devices were 4.93 mA/$cm^2$, 0.56V, 0.40, and 1.12%, respectively.