• Title/Summary/Keyword: nano-reflector

Search Result 32, Processing Time 0.033 seconds

The application of Nano-paste for high efficiency back contact Solar cell (고효율 후면 전극형 태양전지를 위한 나노 Paste의 적용에 대한 연구)

  • Nam, Donghun;Lee, Kyuil;Park, Yonghwan
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2010.11a
    • /
    • pp.53.2-53.2
    • /
    • 2010
  • In this study, we focused on our specialized electrode process for Si back-contact crystalline solar cell. It is different from other well-known back-contact cell process for thermal aspect and specialized process. In general, aluminum makes ohmic contact to the Si wafer and acts as a back surface reflector. And, silver is used for low series resistance metal grid lines. Aluminum was sputtered onto back side of wafer. Next, silver is directly patterned on the wafer by screen printing. The sputtered aluminum was removed by wet etching process after rear silver electrode was formed. In this process, the silver paste must have good printability, electrical property and adhesion strength, before and after the aluminum etching process. Silver paste also needs low temperature firing characteristics to reduce the thermal budget. So it was seriously collected by the products of several company of regarding low temperature firing (below $250^{\circ}C$) and aluminum etching endurance. First of all, silver pastes for etching selectivity were selected to evaluate as low temperature firing condition, electrical properties and adhesive strength. Using the nano- and micron-sized silver paste, so called hybrid type, made low temperature firing. So we could minimize the thermal budget in metallization process. Also the adhesion property greatly depended on the composition of paste, especially added resin and inorganic additives. In this paper, we will show that the metallization process of back-contact solar cell was realized as optimized nano-paste characteristics.

  • PDF

Optical Simulation Study of the Improvement of Color-rendering Characteristics of White Light-emitting Diodes by Using Red Quantum-dot Films (적색 양자점 필름을 이용한 백색 발광 다이오드의 연색성 개선에 대한 광학 시뮬레이션 연구)

  • Lee, Gi Jung;Hong, Seung Chan;Lee, Jung-Gyun;Ko, Jae-Hyeon
    • Korean Journal of Optics and Photonics
    • /
    • v.32 no.4
    • /
    • pp.163-171
    • /
    • 2021
  • Conventional white light-emitting diodes (LEDs) for lighting applications consist of blue LEDs and yellow phosphors, the spectrum of which lacks deep red. To improve the color-rendering characteristics of white LEDs, a red quantum-dot film was applied to the diffuser plate of LED lighting. The mean free paths of the quantum dots and the concentration of the TiO2 particles in the diffuser plate were adjusted to optimize the optical structure of the lighting. The color-rendering index (CRI) was greater than 90 for most conditions, which demonstrates that adoption of the red quantum-dot film is an effective way for improving the color-rendering properties of conventional white LEDs. The angular dispersion of color coordinates could be removed by utilizing the optical cavity formed between the diffuser plate and the reflector on the bottom of the lighting, where multiple passages of the light through the quantum-dot film reduced the differences in optical path length depending on the viewing angle.

Effects of High Neutral Beam Energy on the Properties of Amorphous Carbon Films

  • Lee, Dong-Hyeok;Jang, Jin-Nyeong;Gwon, Gwang-Ho;Yu, Seok-Jae;Lee, Bong-Ju;Hong, Mun-Pyo
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2012.02a
    • /
    • pp.477-477
    • /
    • 2012
  • The effects of argon neutral beam (NB) energy on the amorphous carbon (a-C) films were investigated, while the a-C films were deposited by neutral particle beam assisted sputtering (NBAS) system. The deposition characteristics of these films were studied as a function of NB energy (or reflector bias voltage). The film structures were investigated by Raman spectroscopy. The hardness was measured by nano-indentation tests and the optical band gap was measured by UV-visible spectroscopy.

  • PDF

Design of an Antireflection Coating for High-efficiency Superconducting Nanowire Single-photon Detectors

  • Choi, Jiman;Choi, Gahyun;Lee, Sun Kyung;Park, Kibog;Song, Woon;Lee, Dong-Hoon;Chong, Yonuk
    • Current Optics and Photonics
    • /
    • v.5 no.4
    • /
    • pp.375-383
    • /
    • 2021
  • We present a simulation method to design antireflection coating (ARCs) for fiber-coupled superconducting nanowire single-photon detectors. Using a finite-element method, the absorptance of the nanowire is calculated for a defined unit-cell structure consisting of a fiber, ARC layer, nanowire absorber, distributed Bragg reflector (DBR) mirror, and air gap. We develop a method to evaluate the uncertainty in absorptance due to the uncontrollable parameter of air-gap distance. The validity of the simulation method is tested by comparison to an experimental realization for a case of single-layer ARC, which results in good agreement. We show finally a double-layer ARC design optimized for a system detection efficiency of higher than 95%, with a reduced uncertainty due to the air-gap distance.

Polymeric Waveguide Bio Sensors with Bragg Gratings (브래그 격자 광도파로형 바이오 센서)

  • Lee, Jae-Hyun;Kim, Gyeong-Jo;Oh, Min-Choel
    • Korean Journal of Optics and Photonics
    • /
    • v.17 no.1
    • /
    • pp.54-59
    • /
    • 2006
  • Biophotonic sensors based on polymer waveguide with Bragg reflection grating are demonstrated in this work. Waveguide Bragg reflectors were designed by using the effective index method and the transmission matrix method. The grating pattern was formed by exposing the laser interference pattern on a photoresist. On top of the inverted rib waveguide, the Bragg reflection grating was inscribed by the O2 plasma etching. In order to perform the bio-molecule detection experiment, a calixarene molecule was self-assembled on top of thin Au film deposited on the waveguide Bragg reflector. To measure the response of the sensor, several PBS solutions with different concentrations of potassium ion from 1 pM to $100\;{\mu}M$ were dropped on the sensor surface. The shift of Bragg reflection wavelength was observed from the fabricated sensor device, which was proportional to the concentration of potassium ion ranging from 1 pM to 108 pM.

Study of the Analysis Method for the Aspherical Tolerance of a Korsch Telescope Using a Q Polynomial (Q-Polynomial을 이용한 Korsch 망원경의 비구면 공차 분석 방법 연구)

  • Jun, Won-Kyoun;Lee, Han-Yul;Lee, Sang-min;Kim, Ki-hwan;Park, Seung Han;Jung, Mee-Suk
    • Korean Journal of Optics and Photonics
    • /
    • v.31 no.6
    • /
    • pp.328-333
    • /
    • 2020
  • In this paper, we study the analysis method for the aspherical tolerance of a Korsch telescope using a Q polynomial. It is important to analyze the tolerances for evaluating quality in high-precision fabrication of aspherical reflectors for high-resolution satellites. Thus we express the aspheric surface in terms of a Q polynomial in which each coefficient term is composed independently, and analyze the tolerance of a Korsch telescope. We also analyze the tolerance using Zernike fringe sag, which expresses the shape error of an aspherical mirror. By comparing the two results, we confirm that the Q-polynomial method can be used to analyze an aspherical mirror.

A Study on Performance and Sensitivity Improvement of an Off-axis TMA Telescope Optical System by Changing the Aperture-stop Position (조리개 위치 변경을 통한 비축 삼반사 망원경 광학계의 성능 및 민감도 개선 연구)

  • Lee, Han-Yul;Jun, Won-Kyoun;Lee, Sang-min;Kim, Ki-hwan;Seo, Hyun-Ju;Park, Seung-Han;Jung, Mee-Suk
    • Korean Journal of Optics and Photonics
    • /
    • v.32 no.1
    • /
    • pp.9-14
    • /
    • 2021
  • In this paper we have studied an optical system according to the aperture position of an off-axis TMA telescope for satellites. An off-axis TMA telescope should have high resolution and wide field of view (FOV). In addition, the optical system should have a wide tolerance range, because it is structurally located off-axis and is difficult to assemble. However, there are differences in performance and sensitivity according to the aperture-stop position, so it is important to select a suitable aperture-stop position. Therefore, in this paper we have designed each off-axis TMA telescope according to the aperture-stop position, and have analyzed the performance and sensitivity to suggest a suitable aperture-stop position.

Taguchi method-optimized roll nanoimprinted polarizer integration in high-brightness display

  • Lee, Dae-Young;Nam, Jung-Gun;Han, Kang-Soo;Yeo, Yun-Jong;Lee, Useung;Cho, Sang-Hwan;Ok, Jong G.
    • Advances in nano research
    • /
    • v.13 no.2
    • /
    • pp.199-206
    • /
    • 2022
  • We present the high-brightness large-area 10.1" in-cell polarizer display panel integrated with a wire grid polarizer (WGP) and metal reflector, from the initial design to final system development in a commercially feasible level. We have modeled and developed the WGP architecture integrated with the metal reflector in a single in-cell layer, to achieve excellent polarization efficiency as well as brightness enhancement through the light recycling effect. After the optimization of key experimental parameters via Taguchi method, the roll nanoimprint lithography employing a flexible large-area tiled mold has been utilized to create the 90 nm-pitch polymer resist pattern with the 54.1 nm linewidth and 5.1 nm residual layer thickness. The 90 nm-pitch Al gratings with the 51.4 nm linewidth and 2150 Å height have been successfully fabricated after subsequent etch process, providing the in-cell WGPs with high optical performance in the entire visible light regime. Finally we have integrated the WGP in a commercial 10.1" display device and demonstrated its actual operation, exhibiting 1.24 times enhancement of brightness compared to a conventional film polarizer-based one, with the contrast ratio of 1,004:1. Polarization efficiency and transmittance of the developed WGPs in an in-cell polarizer panel achieve 99.995 % and 42.3 %, respectively.

Effects of Neutral Particle Beam on Nano-Crystalline Silicon Thin Film Deposited by Using Neutral Beam Assisted Chemical Vapor Deposition at Room Temperature

  • Lee, Dong-Hyeok;Jang, Jin-Nyoung;So, Hyun-Wook;Yoo, Suk-Jae;Lee, Bon-Ju;Hong, Mun-Pyo
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2012.08a
    • /
    • pp.254-255
    • /
    • 2012
  • Interest in nano-crystalline silicon (nc-Si) thin films has been growing because of their favorable processing conditions for certain electronic devices. In particular, there has been an increase in the use of nc-Si thin films in photovoltaics for large solar cell panels and in thin film transistors for large flat panel displays. One of the most important material properties for these device applications is the macroscopic charge-carrier mobility. Hydrogenated amorphous silicon (a-Si:H) or nc-Si is a basic material in thin film transistors (TFTs). However, a-Si:H based devices have low carrier mobility and bias instability due to their metastable properties. The large number of trap sites and incomplete hydrogen passivation of a-Si:H film produce limited carrier transport. The basic electrical properties, including the carrier mobility and stability, of nc-Si TFTs might be superior to those of a-Si:H thin film. However, typical nc-Si thin films tend to have mobilities similar to a-Si films, although changes in the processing conditions can enhance the mobility. In polycrystalline silicon (poly-Si) thin films, the performance of the devices is strongly influenced by the boundaries between neighboring crystalline grains. These grain boundaries limit the conductance of macroscopic regions comprised of multiple grains. In much of the work on poly-Si thin films, it was shown that the performance of TFTs was largely determined by the number and location of the grain boundaries within the channel. Hence, efforts were made to reduce the total number of grain boundaries by increasing the average grain size. However, even a small number of grain boundaries can significantly reduce the macroscopic charge carrier mobility. The nano-crystalline or polymorphous-Si development for TFT and solar cells have been employed to compensate for disadvantage inherent to a-Si and micro-crystalline silicon (${\mu}$-Si). Recently, a novel process for deposition of nano-crystralline silicon (nc-Si) thin films at room temperature was developed using neutral beam assisted chemical vapor deposition (NBaCVD) with a neutral particle beam (NPB) source, which controls the energy of incident neutral particles in the range of 1~300 eV in order to enhance the atomic activation and crystalline of thin films at room temperature. In previous our experiments, we verified favorable properties of nc-Si thin films for certain electronic devices. During the formation of the nc-Si thin films by the NBaCVD with various process conditions, NPB energy directly controlled by the reflector bias and effectively increased crystal fraction (~80%) by uniformly distributed nc grains with 3~10 nm size. The more resent work on nc-Si thin film transistors (TFT) was done. We identified the performance of nc-Si TFT active channeal layers. The dependence of the performance of nc-Si TFT on the primary process parameters is explored. Raman, FT-IR and transmission electron microscope (TEM) were used to study the microstructures and the crystalline volume fraction of nc-Si films. The electric properties were investigated on Cr/SiO2/nc-Si metal-oxide-semiconductor (MOS) capacitors.

  • PDF

Study of the Optical System Design of a Reflective LED Stand to Reduce Glare (눈부심 감소를 위한 반사형 LED 스탠드 광학계 설계에 관한 연구)

  • Kong, Mi-Seon;Jung, Mee-Suk
    • Korean Journal of Optics and Photonics
    • /
    • v.31 no.6
    • /
    • pp.334-343
    • /
    • 2020
  • In this paper, a study of the design of a lighting optical system to form indirect light was conducted, to reduce the glare caused by the hot spot of the LED. In the case of using an LED for indoor lighting, glare is caused because of the high luminance and non-uniform luminance distribution. In particular, LED stands are located close to the user's eyes and are used for a long time, so research to reduce glare is essential. Therefore, in this paper an optical system structural study and the design of an LED stand for glare reduction were conducted. Afterward, the luminance analysis and comparison to an existing LED stand product confirmed that the reflective LED stand proposed in this paper had better performance in terms of glare.