Nonsan, South Korea


Nonsan, South Korea
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Cho J.-Y.,Korea University | Kim J.-S.,Korea University | Kim Y.-D.,Korea University | Cha H.J.,Hunetplus | Lee H.,Korea University
Japanese Journal of Applied Physics | Year: 2015

In this study, an oxide-based nano-patterned sapphire substrate (ONPSS) was used as the substrate for a nitride-based light emitting diode (LED) in order to enhance the LED's internal quantum efficiency and light extraction efficiency. The ONPSS was fabricated by a direct spin-on-glass printing technique, which is simple, easy, and relatively low-cost technique. Conventional PSSs are generally fabricated by photolithography and a sapphire etching process. However, the process reported here, it is possible to fabricate an oxide-based PSS without the sapphire etching process. After a GaN-based blue LED device was grown on the ONPSS, we measured the photoluminescence and electroluminescence intensity to confirm the light extraction efficiency and internal quantum efficiency of the LED. Compared to a GaN LED grown on an unpatterned sapphire, the ONPSS-based LED exhibited a 100% increase in light output power without electrical degradation. © 2015 The Japan Society of Applied Physics.

Shin J.-H.,Korea University | Go B.-N.,Korea University | Choi H.-J.,Korea University | Cho J.-Y.,Korea University | And 4 more authors.
Journal of Materials Chemistry C | Year: 2014

UV-curable polysilsesquioxane materials were used to incorporate moth-eye structures on photovoltaic (PV) protective glass. These patterns were formed using a hybrid nanoimprint lithography technique and annealed at 100 °C to evaporate the solvent (xylene). Compared to the bare, un-patterned PV protective glass, the PV protective glass patterned on both sides had superior optical properties. Transmittance of the PV protective glass patterned on both sides increased by up to 3.13% and reflectance decreased by up to 3.42%, and the transmittance was increased for all angles of incidence. Furthermore, the J SC of devices with the PV protective glass patterned on both sides increased by up to 3.15%. Finally, a monitoring system was set up to measure electricity generated by PV modules. The efficiency of the PV module with PV protective glass patterned on both sides was enhanced by up to 12.16% compared with that of the PV module with un-patterned PV protective glass. © the Partner Organisations 2014.

Sun Ryu M.,Kyung Hee University | Jin Cha H.,Hunetplus | Jang J.,Kyung Hee University
Solar Energy Materials and Solar Cells | Year: 2010

We have studied the lifetime improvement of organic solar cells based on conjugated polymer:fullerene blends using a UV absorbing film. The cell using P3HT and PCBM-71 exhibited a conversion efficiency of ∼4.3%, but it decreased with increase in illumination time. The conversion efficiency of the cells with and without UV film decreased to 6.6% and 37.6%, respectively, after 24 h of light exposure under AM1.5. The UV exposure appears to change the P3HT polymer network such that the defects are generated, resulting in the degradation of cell efficiency. It is found that the conversion efficiency of the cell having a 4 um UV blocking layer is higher than that without a UV layer after 12 h of illumination under 120 mW/cm2. © 2009 Elsevier B.V. All rights reserved.

Ryu M.S.,Kyung Hee University | Cha H.J.,Hunetplus | Jang J.,Kyung Hee University
Current Applied Physics | Year: 2010

We studied the performance improvement of organic solar cells by optimizing annealing temperature and time. Thermal annealing enables crystallization and diffusion of the component in the blend. Furthermore, thermal annealing improves the nanoscale morphology which can strongly affect the transport pathways for free charge and also the contact to the electron collecting electrode. We could obtain the high efficiency organic solar cell having the J SC of 14.1 mA/cm 2, the V OC of 0.65 V, the fill factor of 0.6, and the power conversion efficiency of 5.5% by introducing the TiO x interlayer and applying the thermal annealing at 130 °C for 30 min and using regioregular poly(3-hexylthiophene, P3HT) and a soluble fullerene derivative (PCBM-71). © 2009 Elsevier B.V. All rights reserved.

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