스캐터링층 도입에 따른 염료감응태양전지의 물성평가

노윤영 ( Yun Young Noh ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.10

We propose a working electrode with a scattering layer inserted for dye-sensitized solar cells (DSSCs) with the following structure: glass/FTO/blocking layer/TiO2/scattering layer/dye/electrolyte/Pt/ FTO/glass. A working electrode without a scattering layer was also prepared using a similar method for comparison. The microstructure was examined by optical microscopy and field emission scanning electron microscopy (FE-SEM). The photovoltaic properties, such as the short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), energy conversion efficiency (ECE) and impedance were characterized using a solar simulator and potentiostat. FE-SEM confirmed that the blocking layer with 20 nm grains and the scattering layer with 350-450 nm grains had been prepared. The Jsc and Voc increased, and impedance analysis revealed a decrease in the electron transfer resistance and electron recombination resistance at the TiO2/electrolye interface. The ECE with the scattering layer was 6.35%, which was 20% higher than that observed in the ECE without the scattering layer. (Received January 3, 2013)

염료감응태양전지용 Pd 상대전극의 물성 연구

노윤영 ( Yun Young Noh ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.1

Palladium (Pd) nano films were deposited at different thicknesses of 34, 46, and 90 nm by sputtering for use as the counter electrode (CE) in dye sensitized solar cell (DSSC). Conventional Pt layers were also prepared using the same process for comparison. Finally 0.45 cm2 DSSCs employing the Pd or Pt CE were prepared, and their photovoltaic properties and microstructure were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), current-voltage (I-V), and transmission electron microscopy (TEM) characterization. CV showed that the catalytic activity of Pd was lower than that of Pt. Moreover, the catalytic activity of Pd increased with increasing thickness. Impedance analysis revealed huge charge transfer resistance at the Pd interface that decreased with increasing Pd thickness. Pt showed low resistance without a thickness dependence. The I-V result of the DSSC device employing Pd and Pt revealed a mean energy conversion efficiency of 4.32% and 6.57%, respectively. TEM showed that the Pd films were not deposited conformally compared to Pt films. The uneven microstructure of the Pd film can lead huge interface resistance and low efficiency. These results suggest that Pd can be used as the counter electrode in DSSCs instead of conventional Pt but the Pd film uniformity needs to be improved.

레이져 식각된 상대전극이 채용된 염료감응태양전지

노윤영 ( Yun Young Noh ),유기천 ( Ki Cheon Yoo ),고민재 ( Min Jae Ko ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.3

In order to enhance the energy conversion efficiency by increasing the surface area of the counter electrode (CE), we employed different substrates with the flat glass, FTO (fluorine-doped tin oxide), and laser patterned FTO. Ruthenium (Ru) films with thicknesses of 34 and 46 nm were deposited by atomic layer deposition (ALD) on each substrate. In this way, the dye sensitized solar cell (DSSC) device with an area of 0.45 cm2 with a glass/FTO/blocking layer/TiO2/N719(dye)/electrolyte/Ru/substrate structure was prepared. The microstructure of the CE was investigated with FE-SEM, and the photovoltaic properties were characterized by cyclic voltammetry (CV), impedance spectroscopy (EIS), and current-voltage (I-V) measurement. When we assumed the surface morphology as the array of a pyramid (width 0.24, length 0.24, and height 0.14 μm), we determined the surface area of the substrate of the flat glass, FTO, and laser patterned FTO as 1.36×108, 2.32×108, and 2.56×108 μm2, respectively. CV and impedance results revealed an increase in catalytic activity and a decrease in interface resistance with increasing Ru thickness and surface area. When the Ru thickness was 34 nm (and 46 nm), the energy conversion efficiency of each substrate was 1.55% (1.96%), 2.62% (2.92%), and 2.95% (3.32%), respectively. These results suggest that increasing the Ru catalytic layer thickness and surface area of the CE contributed to increasing the efficiency. Moreover, increasing of surface area through laser patterning was more suitable for increasing the efficiency than the conventional flat glass, and FTO substrates.

Al-Ru 이층 상대전극을 채용한 염료감응 태양전지의 물성

노윤영 ( Yun Young Noh ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.8

In order to improve the energy conversion efficiency by applying the Al/Ru bilayer on a flat glass substrate of a counter electrode (CE), a 0.45㎠ dye-sensitized solar cell (DSSC) device with glass/FTO/ blocking layer/TiO2/N719 (dye)/electrolyte/(50 nm Ru-50 nm Al)/glass was prepared. For a comparison, a Ru CE of 100 nm-thickness on a flat glass substrate 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), energy conversion efficiency (ECE), and impedance, were characterized using a solar simulator and potentiostat. By Jsc, Voc, FF and ECE measurements, the ECE of the device with Al/Ru bilayer CE was 2.36%. The increase in efficiency was 1.46 times that of the device with a 100 nm Ru CE. The impedance at the interface between CE and the electrolyte decreased with Al/Ru bilayer films. The results imply that the application of an Al/Ru bilayer film improves the efficiency of DSSC devices. †(Received January 15, 2013)

나노 MgO 분말이 혼합된 하이브리드 페로브스카이트의 물성 변화

노윤영 ( Yun Young Noh ),최민경 ( Min Kyoung Choi ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.9

Glass/FTO/compact TiO2/mesoporous TiO2/perovskite layer dispersed MgO nanopowder structured samples were prepared from a mixture of CH3NH3PbI3 (methylammonium lead iodide, MAPbI3) and MgO with a sol-gel process involving PbI2+MgO and CH3NH3I (methylammonium iodide, MAI). The phase and color change of MAPbI3 with MgO was examined by XRD and micro-Raman analyses, and by using a uv-vis-nir-colorimeter. Optical microscopy and field emission scanning electron microscopy (FE-SEM) were employed to evaluate the evolution of the microstructure. The XRD analysis confirmed that MAPbI3 with MgO added degrades more slowly compared to MAPbI3 alone due to Mg(OH)2 formation. Micro-Raman analysis results showed only the existence of MAPbI3. Optical microscopy and FE-SEM revealed degradation in color and microstructural change in all samples as time passed. However, the degradation was confirmed to occur more slowly for the MAPbI3 with added MgO. A lab color analysis with uv-vis-nir also supported the results of the color changes by degradation. These results indicate that the degradation of MAPbI3 may be dramatically delayed by the addition of nano MgO powders. (Received November 03, 2014)

실링하지 않은 염료감응형 태양전지의 효율 신뢰성 평가

노윤영 ( Yun Young Noh ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.9

A detachable working electrode on different counter electrodes without sealing is proposed for dye-sensitized solar cells (DSSCs) to reduce the time needed for characterizing the photovoltaic properties. The photovoltaic properties were measured with time immediately after injecting the electrolyte and with the number of repetitions of reassembling the DSSC devices. The photovoltaic properties, such as the current density, open circuit voltage, fill factor, and energy conversion efficiency (ECE), were measured using a solar simulator apparatus. The microstructure was examined by optical microscopy. The ECE was checked every two minutes immediately after electrolyte injection. The photovoltaic properties were determined reliably at 10-20 minutes after electrolyte injection due to a trade-off between the diffusion of the electrolyte into the TiO2 layer and the degradation of the electrolyte with time. With the repetition of reassembly, the detachable electrodes might show a reliable ECE until four repetitions. ECE degraded abruptly after five repetitions of the test because of the broken TiO2 layers and spacers. These results suggest that the proposed detachable electrodes without sealing will be suitable for repeated measurements for photovoltaic properties.

나노급 Al/Pt 또는 Ti/Pt 이중 촉매층 도입에 따른 염료감응태양전지의 물성

노윤영 ( Yun Young Noh ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.1

Al/Pt and Ti/Pt bilayers to a flat glass substrate were employed as a counter electrode to improve the energy conversion efficiency of a dye-sensitized solar cell device with a structure of glass/FTO/blocking layer/TiO2/N719(dye)/electrolyte/(50 nmPt-50 nmAl) or (50 nmPt-50 nmTi)/glass. For comparison, a 100 nmthick Pt counter electrode on a flat glass substrate was also prepared using the same method. The sheet resistance was examined by a four point probe. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, energy conversion efficiency, and impedance, were characterized using a solar simulator and potentiostat. The phases of the bilayered films were identified by X-ray diffraction. The measured energy conversion efficiencies of the dye-sensitized solar cell devices with Al/Pt and Ti/Pt bilayer counter electrodes were 5.36% and 5.03%, respectively. The interface resistance at the interface between the counter electrode and electrolyte decreased when the Al/Pt and Ti/Pt bilayer thin films were applied. The new phases of AlPt3 and Pt3Ti led to a decrease in resistivity and an increase in catalytic activity. This suggests that Al/Pt and Ti/Pt bilayer thin films might improve the efficiency of dye-sensitized solar cells.

나노급 Mo/Pt 이중 촉매층 도입에 따른 염료감응태양전지의 물성

노윤영 ( Yun Young Noh ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.3

A Mo/Pt bilayered catalytic layer on a flat glass substrate was used as a counter electrode to improve the energy conversion efficiency of a dye-sensitized solar cell device with the structure of effective area of 0.45 cm2 glass/FTO/blocking layer/TiO2/N719(dye)/electrolyte/50 nm Pt/50 nm Mo/glass. For comparison, 100 nm-thick Pt and Mo counter electrodes on flat glass substrates were also prepared using the same procedure. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, energy conversion efficiency, and impedance, were characterized using a solar simulator and poten-tiostat. The phases and microstructures of the catalytic layers were examined by X-ray diffraction and field emission electron microscopy. The measured energy conversion efficiency of the dye-sensitized solar cell devices with only Pt and Mo/Pt bilayer counter electrodes was 4.60% and 6.30%, respectively. The interface resistance at the interface between the counter electrode and electrolyte decreased when a Mo/Pt bilayer thin film was used. The new phase of Pt3Mo led to an increase in catalytic activity. This suggests that the Mo/Pt bilayered catalytic layers may provide better efficiency in the dye-sensitized solar cells than the conventional Pt layers.

나노급 Cr/Pt 이중 촉매층 도입에 따른 염료감응태양전지의 물성

노윤영 ( Yun Young Noh ),송오성 ( Oh Sung Song ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.4

A Cr/Pt bilayered catalytic layer on a flat glass substrate is used as a counter electrode in order to improve the energy conversion efficiency of a dye-sensitized solar cell device with an effective structure area of 0.45 cm2 glass/FTO/blocking layer/TiO2/N719(dye)/electrolyte/50 nm Pt/50 nm Cr/glass. For comparison, 100 nm-thick Pt and Cr counter electrodes on flat glass substrates are also prepared using the same procedure. The sheet resistance is examined using a four-point probe. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, energy conversion efficiency, and impedance, are characterized using a solar simulator and potentiostat. The phases of the bilayered films are examined using X-ray diffraction. Furthermore, the microstructure of the bilayered films is characterized via field emission electron microscopy. The measured energy conversion efficiencies of the dye-sensitized solar cell devices with only Pt and Cr/Pt bilayer counter electrodes are 4.60% and 6.68%, respectively. The interface resistance at the interface between the counter electrode and electrolyte decreases when a Cr/Pt bilayer thin film is applied. The new phases of Pt3Cr enable an increase in the catalytic activity. This suggests that the Cr/Pt bilayer catalytic layers might improve the efficiency of dye-sensitized solar cells compared with the conventional Pt layers.

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.