• Current Photovoltaic Research
• /
• v.6 no.4
• /
• pp.91-93
• /
• 2018

Polythiophene-$TiO_2$ composite was synthesized with different molar ratios of thiophene and titaniumisopropoxide ($Ti(OPr)_4$) for flexible solar cell application as a flexible electrode or an active material. The $Ti(OPr)_4$ was stabilized by thiophene. The thiophene was polymerized by ferric chloride catalyst. The synthesized polythiophene exhibited strong UV-visible absorption in the range of the wavelength shorter than 500 nm. Field emission scanning electron microscope (FESEM) image of low concentration of $TiO_2$ film showed smooth surface. However, FESEM image of high concentration of $TiO_2$ film exhibited relatively rough surface. Polythiophene concentration dependent strong photoluminescence quenching of surfrhodamine-B was observed.

• Journal of the Microelectronics and Packaging Society
• /
• v.26 no.4
• /
• pp.75-82
• /
• 2019

Flexible solar cells have attracted enormous attention in recent years due to their wide applications such as portable batteries, wearable devices, robotics, drones, and airplanes. In particular, the demands of the flexible silicon and compound semiconductor solar cells with high efficiency and high reliability keep increasing. In this study, we fabricated a flexible InGaP/GaAs double-junction solar module. Then, the effects of the wind speed and ambient temperature on the operating temperature of the solar cell were analyzed with the numerical simulation. The temperature distributions of the solar modules were analyzed for three different wind speeds of 0 m/s, 2.5 m/s, and 5 m/s, and two different ambient temperature conditions of 25℃ and 33℃. The flexibility of the flexible solar module was also evaluated with the bending tests and numerical bending simulation. When the wind speed was 0 m/s at 25 ℃, the maximum temperature of the solar cell was reached to be 149.7℃. When the wind speed was increased to 2.5 m/s, the temperature of the solar cell was reduced to 66.2℃. In case of the wind speed of 5 m/s, the temperature of the solar cell dropped sharply to 48.3℃. Ambient temperature also influenced the operating temperature of the solar cell. When the ambient temperature increased to 33℃ at 2.5 m/s, the temperature of the solar cell slightly increased to 74.2℃ indicating that the most important parameter affecting the temperature of the solar cell was heat dissipation due to wind speed. Since the maximum temperatures of the solar cell are lower than the glass transition temperatures of the materials used, the chances of thermal deformation and degradation of the module will be very low. The flexible solar module can be bent to a bending radius of 7 mm showing relatively good bending capability. Neutral plane analysis was also indicated that the flexibility of the solar module can be further improved by locating the solar cell in the neutral plane.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07a
• /
• pp.484-487
• /
• 2005

In order to find out LC cell spacing method suitable for flexible cholesteric LCDs with high mechanical stability, we carried out bending and mechanical shock tests by using various spacing techniques: bead spacer, photo spacer, polymer wall with bead spacer and polymer wall with photo spacer. As a result, it was found that the spacing method using polymer wall incorporated with photo spacer is the best for flexible cholesteric LCDs in terms of mechanical stability. The investigation is discussed in detail.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.237.2-237.2
• /
• 2005

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.85.1-85.1
• /
• 2011

In this study, Grafoil$^{TM}$ which has comparable electric resistance and chemical stability but is flexible, fragile, and cheap material was adopted as bipolar plates for proton exchange membrane fuel cell(PEMFC) having only one straight line flow channel. Because of its flexibility, pressurizations of cell with various pressures showed different operating characteristics compared to ordinary graphite-used PEMFC. While performances of both cells decreased as these were pressurized, investigation of ohmic and faradaic resistance by electrochemical impedance measurement indicated different tendency of change. Ohmic resistance of graphite-used cell increased with increasing pressure, which is reversed in Grafoil$^{TM}$-used cell. It is speculated that effective chemical reaction area is decreased with increasing pressure in case of graphite-used one, but because of flexible property of Grafoil$^{TM}$, gas diffusion layer in Grafoil$^{TM}$-used cell was well-activated. Different rate of change of faradaic resistances in both cells support this supposition. However, although optimum point of pressurization is found, it is required to investigate other operating conditions because of low performance compared to graphite-used cell.

• Journal of IKEEE
• /
• v.22 no.2
• /
• pp.432-439
• /
• 2018

In this paper, an omnidirectional visible light detector was developed by making the detecting surface of a flexible solar cell in a cylindrical form, which has a uniform receiving pattern in the horizontal plane. This solar cell detector receives simultaneously multiple signal lights incident from different directions and provides electrical power to the ASK demodulator in the receiver. In experiments, time division transmission method was used to receive three signal lights incident from different directions to the solar cell detector. Each signal light was ASK modulated using a carrier of 40 kHz, and the synchronizing pulses required for time division transmission were generated by detecting the 120 Hz AC signal included in the indoor illumination lamp with Cds cells. This receiving structure is useful in constructing an $N{\times}1$ optical link in visible light communication.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.123.1-123.1
• /
• 2017

Hybrid solar cells have intensively studied in recent years due to their advantages such as cost effectiveness and possibility of applications in flexible and transparent devices. It is critical to fabricate individual layer composed of organic and inorganic materials in the hybrid solar cell at low cost. Therefore, it is required to manufacture cheaply and enhance the photon-to-electricity conversion efficiency of each layer in the flexible solar cell industry. In this research, we fabricated pure Cu metal mesh electrode prepared by using electroplating and/or electroless plating on the Ni mold which was manufacture through photolithography, electroforming, and polishing process. Copper mesh was formed on the surface of nickel metal working master when pulsed electrolytic copper deposition were performed at various plating parameters such as plating time, current density, and so on. After electrodeposition at 2ASD for 5~30seconds, the line/pitch/thickness of copper mesh sheet was $1.8{\sim}2.0/298/0.5{\mu}m$.

• Journal of the Korea Society for Simulation
• /
• v.17 no.4
• /
• pp.249-257
• /
• 2008

This paper shows the Applied Q-learning Algorithm which supports selecting the waiting position of a robot and the part serviced next in the Flexible Manufacturing Cell (FMC) that consists of one robot and various types of facilities. To verify the performance of the suggested algorithm, we design the general FMC made up of single transfer robot and multiple machines with a simulation method, and then compare the output with other control methods. As a result of the analysis, the algorithm we use improve the average processing time and total throughputs as well by increasing robot utilization, reversely, by decreasing robot waiting time. Furthermore, because of ease of use compared with other complex ways and its adoptability to real world, we expect that this method contribute to advance total FMC efficiency as well.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.58.1-58.1
• /
• 2011

CIS(CuInSe2)계 화합물 태양전지는 높은 광흡수계수와 열적 안정성으로 고효율 태양전지 제조가 가능하여 태양전지용 광흡수층으로 매우 이상적이다. 미국 NREL에서는 이러한 CIGS 태양전지를 Co-evaporation 방법으로 제조 20%이상의 에너지 변환 효율을 달성하였다고 보고하였다. CIGS 태양전지의 경우 기존의 유리 기판 대신 유연한 철강 기판을 사용해 태양 전지를 flexible하게 제조 할 수 있다는 장점이 있다. 이러한 flexible 태양전지의 경우 기존의 rigid 태양전지의 적용분야 뿐만 아니라 BIPV, 선박, 장난감, 군용, 자동차등 더욱 더 많은 분야에 활용이 가능하다. 본 연구에서는 기존의 rigid한 기판인 soda lime glass와 flexible 기판인 stainless steel 기판으로 소자를 제조하여 효율을 비교 분석 및 stainless steel 기판의 표면 처리 방법에 따라서 표면 조도의 특성을 분석하여 stainless steel 기판별 효율 특성도 비교 분석 하였다. 후면전극으로는 약 $1{\mu}m$의 Mo를 DC Sputtering 방법을 이용하여 증착하였고, CIGS 광흡수층은 약 $2.5{\mu}m$의 두께로 미국의 NREL과 같은 3 stage 방식을 이용하여 광흡수층을 Co-Evaporation 방법으로 제조하였고, 버퍼층인CdS는 약 50nm의 두께로 CBD 방법으로 제조 하였으며, 창층인 ZnO는 약 500nm 두께로 RF Sputtering 방법으로 제조 하였고, 마지막으로 약 $1{\mu}m$ 두께의 Al 전면전극은 Thermal Evaporation 방법으로 제조 하였다. 소자의 물리적, 전기적 특성을 분석하기위해 FE-SEM, AFM, Solar Cell Simulator 분석을 실시하였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.285-288
• /
• 2007

박막형 태양전지 및 플렉서블 태양전지 기판으로 사용되는 금속기판의 우수성은 잘 알려져 있다. 그러나 상용 금속기판이 직면하고 있는 문제점을 보완하기 위해서 전주법으로 제조된 2원합금 금속포일을 개발하였으며, 박막형 및 플렉서블 태양전지의 기판재로 적용가능성을 확인하였다. 일반적으로 태양전지를 제조할 때 열 공정이 수행되며, 이때 기판재와 cell을 구성하는 반도체의 열팽창 계수 차이에 의한 열변형으로 결함이 발생될 수 있고, 태양전지 효율 및 수명을 저하시키는 원인이 될 수 있다. 이러한 원인이 될 수 있는 구성 재료간의 열팽창계수 차이에 의한 cell 의 변형량을 추정하기 위해 유한요소해석 방법을 사용하였다. 유한요소해석을 수행하기 위해 ALGOR 라는 해석 tool 을 사용하였다. 유한요소해석 수행에 사용된 상용 금속인 Mo, Ti, Al, SUS 포일과 전주법으로 제조된 2원합금 금속포일의 열팽창 계수는 실험을 통한 측정치이며, cell을 구성하는 반도체의 열팽창 계수와 열특성은 참고 문헌에 있는 자료들이다. 이 값들을 기반으로 cell 의 구성을 단순화시킨 가상의 태양전지가 제조 공정 온도에서 상온으로 냉각될 때의 열변형량을 계산하였다.