• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3272-3278
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• 2010

Synthesis and structural characterization of peripherally ferrocene-substituted zinc phthalocyanine (ZnPc-Fc) were carried out for efficient far-red/near-IR performance in dye-sensitized nanostructured $TiO_2$ solar cells. Incorporating ferrocene into phthalocyanine strongly improved the dye solubility in polar organic solvents, and reduced surface aggregation due to the steric effect of bulky ferrocene substituents. The involvement of electron transfer reaction pathways between ferrocene and phthalocyanine in ZnPc-Fc was evidenced by completely quenched fluorescence from S1 state (< 0.08% vs ZnPc). Strong absorption bands at 542 and 682 nm were observed in the transient absorption spectroscopy of ZnPc-Fc in DMSO, which was excited at a 670 nm laser pulse with a 15 ps full width at half maximum. Also, the excited state absorption signals at 450 - 600 and 750 - 850 nm appeared from the formation of charge separated state of phthalocyanine's anion. The lifetime of the charge separate state in ZnPc-Fc was determined to be $170{\pm}8$ ps, which was almost 17 times shorter than that of the ZnPc.

• 한국세라믹학회지
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• 제52권5호
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• pp.380-383
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• 2015

We prepared the $TiO_2$ layer with 0 ~ 4 wt% of polystyrene (PS) beads having a radius of 250 nm to increase the dye adsorption and energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC). Then, we fabricated DSSCs using $0.45cm^2$ active area. FE-SEM was used to characterize the microstructure consisting of $TiO_2$ layer and PS beads. UV-VIS-NIR was used to determine the optical absorbance of working electrodes (WEs). Solar simulator and potentiostat were used to determine the photovoltaic properties. We observed that pores having a radius of 250 nm were formed with the density of $0.15ea/{\mu}m^2$ in $TiO_2$ layers after conducting the sintering process. The absorbance in visible light regime was found to increase with the increase in the amount of PS beads. The ECE increased from 4.66% to 5.25% when the amount of PS beads was increased from 0 to 4 wt%. This is because the pores of PS beads increased the adsorption of dye. Our results indicate that the ECE of the DSSCs can be enhanced by the addition of an appropriate amount of PS beads into $TiO_2$ layers.

• 한국세라믹학회지
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• 제53권1호
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• pp.110-115
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• 2016

We prepared a working electrode (WE) coated with 0 ~ 50 nm-thick indium gallium zinc oxide(IGZO) by using RF sputtering to improve the energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC). Transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS) were used to analyze the microstructure and composition of the IGZO layer. UV-VIS-NIR spectroscopy was used to determine the transparency of the WE with IGZO layers. A solar simulator and a potentiostat were used to confirm the photovoltaic properties of the DSSC with IGZO layer. From the results of the microstructural analysis, we were able to confirm the successful deposition of an amorphous IGZO layer with the expected thickness and composition. From the UV-VIS-NIR analysis, we were able to verify that the transparency decreased when the thickness of IGZO increased, while the transparency was over 90% for all thicknesses. The photovoltaic results show that the ECE became 4.30% with the IGZO layer compared to 3.93% without the IGZO layer. As the results show that electron mobility increased when an IGZO layer was coated on the $TiO_2$ layer, it is confirmed that the ECE of a DSSC can be enhanced by employing an appropriate thickness of IGZO on the $TiO_2$ layer.

• 공업화학
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• 제18권5호
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• pp.433-437
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• 2007

본 연구에서는 기능성 근적외선 흡수색소 및 광안정제로 사용되는 bis(dithiobenzil) 금속 화합물은 중간체인 benzoin 및 anisoin을 먼저 합성하고 이들을 전구체로 사용하여 합성하였다. 또한, bis(dithiobenzil) 금속 화합물의 광안정성 효과를 확인하기 위하여 전하발생재료인 squarylium을 합성하였다. 중간체 및 최종 생성물의 구조는 핵자기 공명 분석기와 적외선 분광기를 이용하여 확인하였고, 열적 특성은 시차열분석기 및 열중량분석기를 이용하여 분석하였다. 광학 특성과 광안정성 효과는 UV-Vis-NIR 분광기를 이용하여 측정 분석하였다. 합성한 bis(dithiobenzil) 금속 화합물은 근적외선 영역에서 우수한 흡광특성을 나타내었고, 치환기의 종류 및 위치에 따라 최대흡수파장이 이동하였다. 또한, squarylium에 bis(dithiobenzil) 금속 화합물을 첨가하면 squarylium의 광퇴색현상을 감소시켰다.

• 한국세라믹학회지
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• 제53권1호
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• pp.105-109
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• 2016

We prepared a working electrode (WE) with a blocking layer (BL) containing 0 ~ 0.5 wt% Ag nano powders to improve the energy conversion efficiency (ECE) of dye sensitized solar cell (DSSC). FESEM and micro-Raman were used to characterize the microstructure and phase. UV-VIS-NIR spectroscopy was employed to determine the adsorption of the WE with Ag nano powders. A solar simulator and a potentiostat were used to confirm the photovoltaic properties of the DSSC with Ag nano powders. From the results of the microstructural analysis, we confirmed that Ag nano powders with particle size of less than 150 nm were dispersed uniformly on the BL. Based on the phase and adsorption analysis, we identified the existence of Ag and found that the adsorption increased when the amount of Ag increased. The photovoltaic results show that the ECE became 4.80% with 0.3 wt%-Ag addition compared to 4.31% without Ag addition. This improvement was due to the increase of the localized surface plasmon resonance (LSPR) of the BL resulting from the addition of Ag. Our results imply that we might be able to improve the efficiency of a DSSC by proper addition of Ag nano powder to the BL.

• 한국세라믹학회지
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• 제52권5호
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• pp.384-388
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• 2015

We prepared blocking layers by adding 0.0 ~ 0.6 wt% nano diamond blends (DBs) to $TiO_2$ blocking layers to improve the energy conversion efficiencies (ECEs) of dye sensitized solar cells (DSSCs). TEM and micro-Raman spectroscopy were used to characterize the microstructure and phases of DBs, respectively. Optical microscopy and FE-SEM were used to analyze the microstructure of the $TiO_2$ blocking layer with DBs. UV-VIS-NIR spectroscopy was used to determine the absorbance of the working electrodes. A solar simulator and a potentiostat were used to determine the photovoltaic properties and the impedance of the DSSCs with DBs. From the results of the DBs analysis, we determined a 6.97 nm combination of nano diamonds and graphite. We confirmed that ECE increased from 5.64 to 6.48 % when the added DBs increased from 0.0 to 0.2 wt%. This indicates that the effective surface area and electron mobility increased when DBs were added to the $TiO_2$ blocking layer. Our results indicate that the ECE of DSSCs can be enhanced by adding an appropriate amount of DBs to the $TiO_2$ blocking layers.

• 한국광학회지
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• 제28권1호
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• pp.22-27
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• 2017

본 논문에서는 음향광학 파장선택 필터(acousto-optic tunable filter) 기반의 파장훑음 레이저(wavelength swept laser)를 이용한 시간-인코딩 근적외선 분광 기술(time-encoded near-infrared spectroscopy)을 제안하였다. 파장훑음 레이저는 800 nm 근처 영역에서 이득 스펙트럼을 가지는 반도체 광 증폭기(semiconductor optical amplifier)를 기반으로 제작되었으며, 음향광학 파장선택 필터를 공진기 내부에 삽입함으로써 음향광학 파장선택 필터에 인가되는 전기적 라디오주파수에 따라 출력 파장을 선택할 수 있도록 하였다. 본 연구에서는 종래의 기술인 백색광 분광기 기반의 검출부 분광 근적외선 분광 기술과 제안된 파장훑음 레이저 기반의 광원부 분광 근적외선 분광 기술을 각각 이용하여 근적외선 흡수 염료 샘플의 흡광도를 각기 측정하여 실험적으로 비교함으로써 본 연구에서 제안하는 음향광학 파장선택 필터 기반 파장훑음 레이저를 이용한 근적외선 분광 기술의 특성을 증명하였다.

• Journal of Gastric Cancer
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• 제21권2호
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• pp.191-202
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• 2021

Purpose: A near-infrared (NIR) fluorescence imaging is a promising tool for cancer-specific image guided surgery. Human epidermal receptor 2 (HER2) is one of the candidate markers for gastric cancer. In this study, we aimed to synthesize HER2-specific NIR fluorescence probes and evaluate their applicability in cancer-specific image-guided surgeries using an animal model. Materials and Methods: An NIR dye emitting light at 800 nm (IRDye800CW; Li-COR) was conjugated to trastuzumab and an HER2-specific affibody using a click mechanism. HER2 affinity was assessed using surface plasmon resonance. Gastric cancer cell lines (NCI-N87 and SNU-601) were subcutaneously implanted into female BALB/c nu (6-8 weeks old) mice. After intravenous injection of the probes, biodistribution and fluorescence signal intensity were measured using Lumina II (Perkin Elmer) and a laparoscopic NIR camera (InTheSmart). Results: Trastuzumab-IRDye800CW exhibited high affinity for HER2 (K_D=2.093(3) pM). Fluorescence signals in the liver and spleen were the highest at 24 hours post injection, while the signal in HER2-positive tumor cells increased until 72 hours, as assessed using the Lumina II system. The signal corresponding to the tumor was visually identified and clearly differentiated from the liver after 72 hours using a laparoscopic NIR camera. Affibody-IRDye800CW also exhibited high affinity for HER2 (K_D=4.71 nM); however, the signal was not identified in the tumor, probably owing to rapid renal clearance. Conclusions: Trastuzumab-IRDye800CW may be used as a potential NIR probe that can be injected 2-3 days before surgery to obtain high HER2-specific signal and contrast. Affibody-based NIR probes may require modifications to enhance mobilization to the tumor site.

• 한국재료학회지
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• 제18권10호
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• pp.515-520
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• 2008

We fabricated 10 nm-$TiO_2$ thin films for DSSC (dye sensitized solar cell) electrode application using ALD (atomic layer deposition) method at the low temperatures of $150^{\circ}\;and\;250^{\circ}$. We characterized the crosssectional microstructure, phase, chemical binding energy, and absorption of the $TiO_2$ using TEM, HRXRD, XPS, and UV-VIS-NIR, respectively. TEM analysis showed a 10 nm-thick flat and uniform $TiO_2$ thin film regardless of the deposition temperatures. Through XPS analysis, it was found that the stoichiometric $TiO_2$ phase was formed and confirmed by measuring main characteristic peaks of Ti $2p^1$, Ti $2p^3$, and O 1s indicating the binding energy status. Through UV-VIS-NIR analysis, ALD-$TiO_2$ thin films were found to have a band gap of 3.4 eV resulting in the absorption edges at 360 nm, while the conventional $TiO_2$ films had a band gap of 3.0 eV (rutile)${\sim}$3.2 eV (anatase) with the absorption edges at 380 nm and 410 nm. Our results implied that the newly proposed nano-thick $TiO_2$ film using an ALD process at $150^{\circ}$ had almost the same properties as thsose of film at $250^{\circ}$. Therefore, we confirmed that the ALD-processed $TiO_2$ thin film with nano-thickness formed at low temperatures might be suitable for the electrode process of flexible devices.

• 한국재료학회지
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• 제26권4호
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• pp.194-199
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• 2016

We prepared polymethyl methacrylate (PMMA) beads with a particle size of 80 nm to improve the energy conversion efficiency (ECE) by increasing the effective surface area and the dye absorption ability of the working electrodes (WEs) in a dye sensitized solar cell (DSSC). We prepared the $TiO_2$ layer with PMMA beads of 0.0~1.0 wt%; then, finally, a DSSC with $0.45cm^2$ active area was obtained. Optical microscopy, transmission electron microscopy, field emission scanning electron microscopy, and atomic force microscopy were used to characterize the microstructure of the $TiO_2$ layer with PMMA. UV-VIS-NIR was used to determine the optical absorbance of the WEs with PMMA. A solar simulator and a potentiostat were used to determine the photovoltaic properties of the PMMA-added DSSC. Analysis of the microstructure showed that pores of 200 nm were formed by the decomposition of PMMA. Also, root mean square values linearly increased as more PMMA was added. The absorbance in the visible light regime was found to increase as the degree of PMMA dispersion increased. The ECE increased from 4.91% to 5.35% when the amount of PMMA beads added was increased from 0.0 to 0.4 wt%. However, the ECE decreased when more than 0.6 wt% of PMMA was added. Thus, adding a proper amount of PMMA to the $TiO_2$ layer was determined to be an effective method for improving the ECE of a DSSC.