Properties of Working Electrodes with Polystyrene Beads Addition in Dye Sensitized Solar Cells

Noh, Yunyoung,Choi, Minkyoung,Song, Ohsung The Korean Ceramic Society 2015 한국세라믹학회지 Vol.52 No.5

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.

Properties of Blocking Layer with Ag Nano Powder in a Dye Sensitized Solar Cell

Noh, Yunyoung,Kim, Kwangbae,Choi, Minkyoung,Song, Ohsung The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.1

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.

Properties of the Dye Sensitized Solar Cell with Localized Surface Plasmon Resonance Inducing Au Nano Thin Films

Noh, Yunyoung,Kim, Kwangbae,Choi, Minkyoung,Song, Ohsung Materials Research Society of Korea 2016 한국재료학회지 Vol.26 No.8

We improve the energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC) by preparing a working electrode (WE) with localized surface plasmon resonance (LSPR) by inducing Au thin films with thickness of 0.0 to 5.0 nm, deposited via sputtering. Field emission scanning electron microscopy and atomic force microscopy were used to characterize the microstructure of the blocking layer (BL) of the Au thin films. Micro-Raman measurement was employed to confirm the LSPR effect, and a solar simulator and potentiostat were used to evaluate the photovoltaic properties, including the impedance and the I-V of the DSSC of the Au thin films. The results of the microstructural analysis confirmed that nano-sized Au agglomerates were present at certain thicknesses. The photovoltaic results show that the ECE reached a value of 5.34% with a 1-nm thick-Au thin film compared to the value of 5.15 % without the Au thin film. This improvement was a result of the increase in the LSPR of the $TiO_2$ layer that resulted from the Au thin film coating. Our results imply that the ECE of a DSSC may be improved by coating with a proper thickness of Au thin film on the BL.

Properties of Working Electrodes with Nano YBO₃:Eu³⁺ Phosphor in a Dye Sensitized Solar Cell

Noh, Yunyoung,Choi, Minkyoung,Kim, Kwangbae,Song, Ohsung The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.2

We added 0 ~ 5 wt% $YBO_3:Eu^{3+}$ nano powders in a scattering layer of a working electrode to improve the energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC). FESEM and XRD were used to characterize the microstructure and phase. PL and micro Raman were used to determine the fluorescence and the composition of $YBO_3:Eu^{3+}$ phosphor. A solar simulator and a potentiostat were used to confirm the photovoltaic properties of the DSSC with $YBO_3:Eu^{3+}$. From the results of the microstructure and phase of the fabricated $YBO_3:Eu^{3+}$ nano powders, we identified $YBO_3:Eu^{3+}$ having particle size less than 100 nm. Based on the microstructure and micro Raman results, we confirmed the existence of $YBO_3:Eu^{3+}$ in the scattering layer and found that it was dispersed uniformly. Through photovoltaic properties results, the maximum ECE was shown to be 5.20%, which can be compared to the value of 5.00% without $YBO_3:Eu^{3+}$. As these results are derived from conversion of light in the UV range into visible light by employing $YBO_3:Eu^{3+}$ in the scattering layer, these indicate that the ECE of a DSSC can be enhanced by employing an appropriate amount of $YBO_3:Eu^{3+}$.

작동전극부에 나노다이아몬드를 첨가한 염료감응형 태양전지의 물성 연구

노윤영 ( Yunyoung Noh ),김광배 ( Kwangbae Kim ),최민경 ( Minkyoung Choi ),송오성 ( Ohsung Song ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.1

We prepared a TiO2 blocking layer containing 0~0.5 wt% nano diamonds (NDs) to increase the effective surface area of working electrodes in a dye sensitized solar cell (DSSC). The result was a DSSC with a 0.45 cm2 active area of a glass/FTO/blocking layer (TiO2 with NDs)/TiO2/dye/electrolyte/100 nm Pt/glass structure. The microstructure of the blocking layer was examined by optical microscope, FESEM, and AFM. UV-VIS-NIR was used to determine the optical absorbance of the working electrodes containing NDs. The photovoltaic properties for the ND added DSSC, such as short circuit current density, open circuit voltage, fill factor, energy conversion efficiency, and impedance, were checked using a solar simulator and potentiostat. Microstructure characterization showed that the NDs were evenly dispersed in the blocking layer. The absorbance in the visible light regime increased as the ND content increased. The photovoltaic properties indicated that energy conversion efficiency increased from 3.53% to 4.96% with 0 wt% and 0.4 wt% ND addition. This was due to the decreased interface resistance of the working electrode and the increased surface area and shunt resistance of the blocking layer resulting from the addition of the NDs. The DSSC with 0.5 wt% NDs was less efficient due to a reduction of the effective electron transport area caused by excess NDs. Our results suggest that we can improve the efficiency of a DSSC by proper addition of NDs into the blocking layer.

염료감응태양전지에서 Pd 촉매층의 전해질과의 반응에 따른 특성 저하

노윤영(Noh, Yunyoung),송오성(Song Ohsung) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.4

기존 DSSC의 상대전극을 TCO-less로 하여 도전성과 촉매기능을 동시에 가지고 있는 Pd의 안정성 확인을 위해 열증착기를 채용하여 유리기판 전면에 Pd를 90nm 두께로 증착하고 전해질과의 반응 안정성을 확인하였다. 0.45cm2급 면 적을 가진 glass/FTO/blocking layer/TiO₂/dye/electrolyte(10 mM LiI + 1 mM I2 + 0.1 M LiClO₄ in acetonitrile solution)/Pd/glass 구조의 DSSC 소자를 만들고, 시편제작 1시간, 12시간 후의 변화를 육안분석, 광학현미경과 FESEM을 이용하여 미세구조 분석을 진행하고, 전기적 분석은 각각 C-V(cyclic voltammetry measurements), I-V(current voltage) 분석 을 통해 확인하였다. 미세구조 분석을 통하여 시간이 지남에 따라 확연히 Pd과 전해질이 반응하여 부식되는 것을 확인하 였고, 전기적으로도 시간이 지남에 따라 촉매활동도와 효율이 감소하는 것을 확인하였다. 최종 효율은 1시간 후에는 0.34%의 광전효율을 보였으나 12시간 후에는 0.15%를 나타내어 약 44%로 감소하였다. 따라서 염료감응태양전지에 Pd촉 매를 채용하기 위해 I-/I3 - 전해질이 아닌 다른 전해질을 사용하거나 Pd 전극이 아닌 다른 촉매재를 사용해야 함을 확인하였다. A TCO-less palladium (Pd) catalytic layer on the glass substrate was assessed as the counter electrode (CE) in a dye sensitized solar cell (DSSC) to confirm the stability of Pd with the I-/I3 -electrolyte on the DSSC performance. A 90nm-thick Pd film was deposited by a thermal evaporator. Finally, DSSC devices of 0.45cm2 with glass/FTO/blocking layer/TiO₂/dye/electrolyte(10 mM LiI + 1 mM I2 + 0.1 M LiClO₄ in acetonitrile solution)/Pd/glass structure was prepared. We investigated the microstructure and photovoltaic property at 1 and 12 hours after the sample preparation. The optical microscopy, field emission scanning electron microscopy (FESEM), cyclic voltammetry measurement (C-V), and current voltage (I-V) were employed to measure the microstructure and photovoltaic property evolution. Microstructure analysis showed that the corrosion by reaction between the Pd layer and the electrolyte occurred as time went by, which led the decrease of the catalytic activity and the efficiency. I-V result revealed that the energy conversion efficiency after 1 and 12 hours was 0.34% and 0.15%, respectively. Our results implied that we might employ the other non- I-/I3 -electrolyte or the other catalytic metal layers to guarantee the long term stability of the DSSC devices.

나노급 Cr/Pt 이중층이 사용된 염료감응태양전지의 저온 열처리에 따른 물성변화

노윤영 ( Yunyoung Noh And ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.10

Abstract: The properties of the Cr/Pt bilayered catalytic layer with additional low temperature annealing using a dye sensitized solar cell (DSSC) were investigated. A DSSC device with a structure with an effective area of 0.45 cm2 glass/FTO/blocking layer/TiO2/N719 (dye)/electrolyte/50 nm Pt/50 nm Cr/glass was prepared. For comparison, 100 nm-thick Pt and Cr counter electrodes on flat glass substrates were also prepared using the same procedure. The sheet resistance was examined using a four point probe. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, energy conversion efficiency (ECE), and impedance, were characterized using a solar simulator and potentiostat. The phases of the bilayered films were examined by X-ray diffraction. The microstructure of the bilayered films was characterized by atomic force microscopy. The measured sheet resistance of the counter electrode with annealing increased to. The measured ECE of the dye-sensitized solar cell devices with vacuum annealed Cr/Pt bilayer counter electrodes decreased abruptly. The interface resistance at the interface between the counter electrode and electrolyte increased as the annealing time increased. The increase in catalytic activity of the Cr/Pt bilayer before annealing resulted from the effect of a compressive strain field. After 10 minutes, the strain field was removed by annealing. The new phases of Pt3Cr and CrPt by annealing led to drastically decreased catalytic activity.

코발트실리사이드 상대전극을 채용한 염료감응형 태양전지의 물성 연구

노윤영 ( Yunyoung Noh ),김광배 ( Kwangbae Kim ),송오성 ( Ohsung Song ) 대한금속재료학회(구 대한금속학회) 2017 대한금속·재료학회지 Vol.55 No.1

Cobalt silicide was used as a counter electrode to replace the Pt catalytic layer of a dye-sensitized solar cell (DSSC) device. 100 nm Si/ 100 nm Co on quartz were formed by sputtering, and cobalt-silicides were formed by vacuum heat treatment at 500 ℃ and 700 ℃ for 30 min, respectively. Field emission scanning electron microscopy (FE-SEM) was used to analyze the surface microstructure. X-ray diffraction (XRD) and Auger electron spectroscopy (AES) depth profiling analysis were used to confirm the phases. Also, cyclic-voltammetry (CV) analysis was employed to confirm the catalytic activity, and photovoltaic properties were confirmed using a simulator and potentiostat. The microstructure analysis indicated that the 500 ℃ and 700 ℃ silicidation led to a uniform planar layer, and island-like agglomerates, respectively. In the XRD and AES results, those phases were structures of quartz/CoSi/Co and quartz/dot-(CoSi₂/Co). CV analysis showed that Si/Co and CoSi/Co exhibited catalytic activity, while dot-(CoSi₂/Co) did not show catalytic activity due to the isolated dot structure. The energy conversion efficiencies of DSSCs with CoSi/Co and dot-(CoSi₂/Co) were 3.75% and 0%, respectively, while that of Pt employed DSSC was 5.13%. Our result implies that using the nano-thick CoSi as a reduction catalytic layer may be an effective replacement for Pt. (Received March 4, 2016; Acceted July 22, 2016)

염료감응태양전지의 Au/Pt 이중 촉매층의 전해질과의 반응에 따른 열화

노윤영(Noh, Yunyoung),송오성(Song Ohsung) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.6

염료감응형 태양전지 상대전극부에 Au/Pt 이중 촉매층 적용에 따른 전해질과의 반응안정성 확인과 에너지변환효율 변화를 확인하기 위해 0.45cm2 면적을 가진 glass/FTO/blocking layer/TiO₂/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 확 인하였다. Au/Pt 이중층과 전해질의 반응을 확인하기 위해 광학현미경을 통해 전해질 주입 후 0∼25분 후 이중층의 미세구조 를 확인하였다. 광전기적 특성 분석 결과, 평탄한 유리기판 위의 단일층 Pt의 에너지변환효율은 4.60%를 나타내고 시간 의존 성이 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 촉매활성 도와 효율이 감소하는 것을 확인하였다. 따라서 염료감응태양전지에 Au/Pt 촉매는 단기적으로는 기존 Pt only보다 우수하였 으나 장기적으로는 전해질과의 안정성이 미흡함을 확인하였다. A 0.45 cm2 DSSC device with a glass/FTO/blocking layer/TiO₂/N719(dye)/electrolyte/50 nm-Pt/50 nm-Au/FTO/glass was prepared to examine the stability of the Au/Pt bilayered counter electrode (CE) with electrolyte and the energy conversion efficiency (ECE) of dye-sensitized solar cells (DSSCs). For comparison, a 100 nm-thick Pt only CE DSSC was also prepared using the same method. The photovoltaic properties, such as the short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), and ECE, were checked using a solar simulator and potentiostat with time after assembling the DSSC. The microstructure of the Au/Pt bilayer was examined by optical microscopy after 0∼25 minutes. The ECE of the Pt only CE-employed DSSC was 4.60 %, which did not show time dependence. On the other hand, for the Au/Pt CE DSSC, the ECEs after 0, 5 and 15 minutes were 5.28 %, 3.64 % and 2.09 %, respectively. The corrosion areas of the Au/Pt CE determined by optical microscopy after 0, 5, and 25 minutes were 0, 21.92 and 34.06 %. These results confirmed that the ECE and catalytic activity of Au/Pt CE decreased drastically with time. Therefore, a Au/Pt CE-employed DSSC may be superior to the Pt only CE-employed one immediately after integration of the device, but it would degrade drastically with time.

노인에서 주관적으로 지각한 신체 및 정신건강수준이 인지감퇴에 미치는 영향

권윤영(Yunyoung Kwon),손상준(Sang Joon Son),이윤환(Yunhwan Lee),백종환(Jong Hwan Back),노재성(Jai Sung Noh),고상현(Sang Hyun Koh),김현정(Hyun Chung Kim),김진주(Jinju Kim),박미애(Mi Ae Park),홍창형(Chang Hyung Hong) 대한노인정신의학회 2013 노인정신의학 Vol.17 No.1

Objectives:The aim of this study was to describe subjective physical and mental health assessed by the single item self-rated physical health (SRPH), and self-rated mental health (SRMH) had influence on the cognitive decline in community-dwelling elderly. Methods:This study was based on the Suwon Project, a cohort comprising of non-random convenience samples of ethnic Koreans aged 60 years and above. 1,356 individuals were assessed at 2 time points 2 years apart for questionnaire which included demographic characteristics, medical history, Korean Mini-Mental State Examination (K-MMSE), Korean version of Geriatric Depression Scale (SGDS-K), SRPH, and SRMH. Multiple logistic regression was used to assess K-MMSE score change from the SRPH, and SRMH. Results:At baseline, both SRPH (β=0.18, p<0.01) and SRMH (β=0.19, p<0.01) score positively associated with the K-MMSE score. At follow-up, subjects with baseline lower SRMH score had significantly greater decline in K-MMSE score (β=0.09, p=0.007). However, baseline SRPH score showed no effect to follow up K-MMSE score before and after adjusting age, sex, education, number of chronic disease, SGDS-K, and baseline K-MMSE score (p=0.89). Conclusion:Brief and easily collected subjective mental health may predict the risk of cognitive decline, but subjective physical health may not.