• Title/Summary/Keyword: Light Emitting System

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Performance of Organic light-emitting diode by various surface treatments of indium tin oxide (Indium tin oxide 기판의 표면처리에 따른 유기 발광다이오드의 특성)

  • Kim, Sun-Hyuk;Han, Jeong-Whan
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.39 no.9
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    • pp.1-10
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    • 2002
  • We have done various treatments of indium tin oxide (ITO) surface for organic light-emitting diodes (OLEDs), and investigated the surface states by different surface treatments using atomic force microscopy (AFM) and Auger electron spectroscopy (AES). We have fabricated OLEDs deposited by ultra-high vacuum molecular beam deposition system and studied the characteristics of the OLEDs. We have observed the dramatical improvement of the performance of OLEDs fabricated on ITO substrates treated by $O_2$ plasma treatment reduces the carbon comtamination of ITO surfaces and increases the work function of ITO.

A Study on Realization of Visible Light Communication System for Power Line Communication Using 8-bit Microcontroller

  • Yun, Ji-Hun;Hong, Geun-Bin;Kim, Yong-Kab
    • Transactions on Electrical and Electronic Materials
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    • v.11 no.5
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    • pp.238-241
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    • 2010
  • The purpose of this study is to solve the problems of radio frequency bandwidth frequency depletion, confusion possibilities, and security that are in current wireless communications systems, and to confirm the possibility of applying those solutions for the next generation network. To solve the problems of the current wireless communications system, a visible light communications system for power line communication (PLC) via 8-bit microcontroller is created and the capacity is analyzed. The exclusive PLC chip APLC-485MA, an 8-bit ATmega16 microcontroller, high brightness 5pi light emitting diodes (LEDs), and the LLS08-A1 visible light-receiving sensor were used for the transmitter and receiver. The performance was analyzed using a designed program and an oscilloscope. The voltage change was measured as a function of distance from 10-50 cm. Blue LEDs showed the best performance among the measured LED types, with 0.47 V of voltage loss, but for a distance over 50 cm, precise data was not easy to obtain due to the weak light. To overcome these types of problems, specific values such as the changing conditions and efficiency value relevant to the light emitting parts and the visible light-receiving sensor should be calculated, and continuous study and improvements should also be realized for better communication conditions.

LED application VLC information network system configuration research (LED를 응용한 VLC 정보 네트워크 시스템 구성 연구)

  • lee, Jun-myung;Jang, Tae-su;Kang, Hyng-kil;Kim, Yong-Kab
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.10a
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    • pp.13-14
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    • 2012
  • Than fluorescent lamps or light bulbs, long life, small power consumption and to the development of modern technology, LED (Light Emitting Diode) devices have the advantage of easy control. For these reasons, using the LED device, lighting has been widely used. LED using optical fiber technology using LED lighting technology with the development of wireless communication technology is attracting attention again. Using LED lights this study analyzed the performance of the technology transfer and implementation of the information transmission system of the visible light communication using LED lighting of the White Visible Light Communication (VLC) based PC module transmitter and receiver modules. Has made a system that can transmit information more than the value of the initial distance ~ 50cm, depending on the presence or absence of the lens, in order to increase the efficiency of the LED modules with different efficiencies that could confirm the performance of the implementation of the research, analysis, and application methods. and about the possibility that you want to check.

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A LED Light Communication Transceiver Module for Ubiquitous Sensor Networks (유비쿼터스 센서 네트워크용 LED 가시광통신 송수신 모듈 및 효율 연구)

  • Jang, Tae-Su;Kwon, Jae-Hyun;Kim, Yong-Kab;Park, Choon-Bae
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.6
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    • pp.1513-1518
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    • 2012
  • This paper is implemented media transmission system of VLC transmitter and receiver module using LED of White lighting that is based on PC module and to transmission technology for performance analysis. To realize LED visible light communication receiver is used 1~12 LED light-emitting device and transmitter is used a variable sensor. Developed initial distance of the tranceiver is more than 0~1m for LED VLC and the overall system transmission speed is achieved on variable having Visible light media transmission system. Composition to PC module with LED module and infrared sensor for performance analysis, predict and analyze the communication distance, check about the possibility of application methods. Measure each performance when the lens wearing and not wearing in order to increase the overall efficiency of the LED module, can know that increase efficiency of approximately 20%.

Development of Current Control System for Solar LED Street Light System

  • Kim, Byun-Gon;Kim, Kwan-Woong;Jang, Tae-Su;Lee, Jun-Myung;Kim, Yong-Kab
    • International journal of advanced smart convergence
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    • v.1 no.1
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    • pp.52-56
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    • 2012
  • As inexhaustible clean energy, solar energy will be the most ideal green energy in the 21st century. The effective method to convert solar energy into electrical energy is by solar photovoltaic power generation technologies. LED Emitting Diode is a kind of component which can transform electricity into visible light. As the smart current control system for photovoltaic street lights, the proposed system has improved the battery charging and discharging mechanism to extend the lifespan and effectively controls the LED discharge current according to battery charge state and lighting.

Enhancement of Light Extraction Efficiency of GaN Light Emitting Diodes Using Nanoscale Surface Corrugation (나노크기 표면 요철을 이용한 GaN LED의 광추출효율 향상)

  • Jung, Jae-Woo;Kim, Sarah;Jeong, Jun Ho;Jeong, Jong-Ryul
    • Korean Journal of Materials Research
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    • v.22 no.11
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    • pp.636-641
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    • 2012
  • In this study, we have investigated highly efficient nanoscale surface corrugated light emitting diodes (LEDs) for the enhancement of light extraction efficiency (LEE) of nitride semiconductor LEDs. Nanoscale indium tin oxide (ITO) surface corrugations are fabricated by using the conformal nanoimprint technique; it was possible to observe an enhancement of LEE for the ITO surface corrugated LEDs. By incorporating this novel method, we determined that the total output power of the surface corrugated LEDs were enhanced by 45.6% for patterned sapphire substrate LEDs and by 41.9% for flat c-plane substrate LEDs. The enhancement of LEE through nanoscale surface corrugations was studied using 3-dimensional Finite Different Time Domain (FDTD) calculation. From the FDTD calculations, we were able to separate the light extraction from the top and bottom sides of device. This process revealed that light extraction from the top and bottom sides of a device strongly depends on the substrate and the surface corrugation. We found that enhanced LEE could be understood through the mechanism of enhanced light transmission due to refractive index matching and the increase of light scattering from the corrugated surface. LEE calculations for the encapsulated LEDs devices also revealed that low LEE enhancement is expected after encapsulation due to the reduction of the refractive index contrast.

A Study on ZnSSe : Te/ZnMgSSe DH Structure Blue and Green Light Emitting Diodes

  • Lee Hong-Chan
    • Journal of Advanced Marine Engineering and Technology
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    • v.29 no.7
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    • pp.795-800
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    • 2005
  • The optical properties of $ZnS_{y}Se_{1-x-y}:Te_x\;(x\;<\;0.08,\;y\∼0.11$) alloys grown by molecular beam epitaxy (MBE) have been investigated by photoluminescence (PL) and PL-excitation (PLE) spectroscopy. Good optical properties and high crystal quality were established with lattice match condition to GaAs substrate. At room temperature, emission in the visible spectrum region from blue to green was obtained by varying the Te content of the ZnSSe:Te alloy. The efficient blue and green emission were assigned to $Te_{1}$Tel and $Te_{n}$ (n$\geq$2) cluster bound excitons, respectively. Bright blue (462 nm) and green (535 nm) light emitting diodes (LEDs) have been developed using ZnSSe:Te system as an active layer.

Efficient Deep-Blue Organic Light-emitting Diodes with Double-Emission Layers

  • Seo, Ji-Hoon;Park, Jung-Sun;Seo, Bo-Min;Lee, Kum-Hee;Park, Jung-Keun;Yoon, Seung-Soo;Kim, Young-Kwan
    • Journal of Information Display
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    • v.10 no.3
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    • pp.107-110
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    • 2009
  • Efficient deep-blue organic light-emitting diodes were demonstrated using 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl doped in double-emission layers (D-EMLs). The D-EML system, which consists of 2-methyl-9,10-di(2-naphthyl)anthracene and 1,4-(dinaphthalen-2-yl)-naphthalene as blue hosts, was employed to broaden the recombination zone and to ensure the good confinement of the holes and electrons. The optimized device showed a peak current efficiency of 4.47 cd/A, a peak external quantum efficiency of 4.09%, and Commission Internationale de L'Eclairage coordinates of (0.16, 0.10).

Blue Light Emitting Electroluminescence Diode (Coronene을 이용한 청색 유기전계 발광 소자의 개발)

  • Lim, Sung-Taek;Shin, Dong-Myung;Roh, Suk-Won
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1377-1378
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    • 1998
  • Blue light emitting electroluminescence(EL) diodes were fabricated utilizing Coronene and some organic materials. Coronene showed photoluminescence(PL) peak at 450nm in solution with high quantum efficiency. Multi layer system was applied to fabricate EL diode utilizing Coronene. The device showed didode-like applied voltage-current relationship. And blue light emitting was observed. The decay time of device was in a scale of some seconds. The trun-on voltage of device was about 9 V.

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Development of the Light Emitting System embedded Concrete Curb (발광체 인입형 콘크리트 경계블록 개발)

  • Bae, Hyun-Ung;Yun, Kyung-Min;Sung, Ik-Hyun;Lee, Chin-Ok;Lim, Nam-Hyoung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.8
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    • pp.3741-3746
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    • 2012
  • The safety accidents due to the insufficient visibility are frequently occurred at the coastal zone. Therefore, safety facilities that provide visibility are certainly required to prevent accidents. In order to solve this demand, the concept of the light emitting system embedded concrete (LESeCON) are established and then concrete curb is produced for application to the coastal zone. To investigate the mechanical and functional performance of concrete curb developed in this study, the bending strength test and the visibility test are conducted.