Kwan Hyun Cho

Surface plasmonic controllable enhanced emission from the intrachain and interchain excitons of a conjugated polymer

We demonstrate selectively enhanced emission by controlling the intrachain and interchain excitons of a conjugated polymer through adjusting surface plasmons. Enhanced light emission from the intrachain excitons was observed by coupling the localized surface plasmon resonance with the intrachain band of the conjugated polymer using Ag nanoparticles. Light emission from the interchain excitons was enhanced by exploiting both the increased strength of the interchain dipole due to the image dipole and the coupling between excitons and surface plasmon polaritons (SPPs). As the Ag nanostructures become complete films, light emission from the interchain excitons increased.

Wall Voltage and Priming Effect Due to Auxiliary Electrode in AC PDP With Auxiliary Electrode

Variation of wall voltage and priming effect due to an auxiliary electrode are investigated with the aim of attaining a better understanding of the discharge phenomenon in an ac plasma display panel with an auxiliary electrode. A periodic positive pulse, which is applied to the auxiliary electrode during afterglow, reduced wall charges accumulated on the auxiliary and sustain electrodes so that discharge current decreased with an increase of auxiliary-pulse voltage. In addition, the auxiliary pulse influenced on the priming particles so that the optical output was not changed as much as the reduced current and sustain voltage was lowered. Based on these results, modified auxiliary-pulse waveforms, i.e., dual auxiliary pulses, were applied to the auxiliary electrode to utilize more priming particles to improve luminous efficacy. The proposed auxiliary waveforms improved IR efficiency by 10%-15% as compared to that obtained with a single auxiliary pulse.

Influence of Gold Nanoparticles on the Characteristics of Plasma Display Panels

This paper proposes a modified alternating current plasma display panel (PDP) in which gold nanoparticles are incorporated into a bare MgO layer to enhance the performance of the protective layer. The proposed structures ion-induced secondary electron yield, which is expressed in a gamma value ( value) is greater than that of a bare MgO layer; as a result, the operating voltage decreases by 10 V to 20 V. The integration of emitted infrared (IR) light and the power density consumed by the discharge current are both increased, but the ratio of increment is greater for the case of the IR light. Consequently, IR efficacy is increased. The IR response time of the sustain discharge and the address discharge time lag are reduced by the enhanced wall charge accumulation characteristic and the exoelectron emission property. The results of ultraviolet photoelectron spectroscopy show that a MgO layer with Au nanoparticles has a lower work function than a conventional bare MgO layer. Furthermore, the structure that is not flattened by nanoparticles seems to enhance the secondary electron emission property of the MgO protective layer. Consequently, the value is enhanced by the two reasons previously mentioned.

Surface plasmon-waveguide hybrid polymer light-emitting devices using hexagonal Ag dots.

We investigated surface plasmon-waveguide hybrid resonances for enhancement of light emission in polymer light-emitting diodes (PLEDs). Hybrid waveguide-plasmon resonances in the visible range for waveguide mode and near IR range for surface plasmons were observed by incorporation of hexagonal Ag dot arrays. Considerable overlap between the emission wavelength of the PLEDs and the waveguide mode by an Ag dot array with a lattice constant of 500 nm was observed. Because of enhanced light extraction by Bragg scattering of waveguide modes, photoluminescence (PL) and electroluminescence (EL) were increased by 70% and 50%, respectively.

Use of zeolites in the capture of charged particles from plasma

The zeolites NaA and 13X were introduced to a coplanar discharge cell to investigate the behavior of charged particles from plasma. The zeolite crystals were attached to the surface without blocking their nanopores. The memory margin related to the accumulated charged particles on the surface indicated that the zeolites absorb charged particles. This phenomenon was also observed at the displacement and discharge current plots. Zeolites with a different window size cause abnormally high displacement and a saturation phenomenon of discharge currents. Note in particular that NaA seems to not only absorb charged particles but also capture gas molecules.

The Effect of Disordered Microscale Holes in the Front Dielectric Layer of AC Plasma Display Panels

Using polymethyl methacrylate (PMMA) beads, disordered microscale holes were fabricated in the front dielectric layer of ac plasma display panels. The density of the disordered microscale holes was easily controlled by varying the weight percentage of the PMMA beads. As their density increased, the voltage of self-erasing discharge and the minimum sustain voltage decreased. In addition, the sustain discharge time lag was improved according to the measurement results of the response time and spatiotemporal infrared emission from an intensified charge-coupled device camera. The wall voltage at the state of sustain discharge was investigated by measuring the threshold voltage using wall voltage measurement system. In the test panel of the front dielectric layer with disordered microscale holes, the wall voltage increased. In addition, the increase in the wall voltage at the state of sustain discharge was improved as the density of the disordered microscale holes increased. The decrease in the self-erasing discharge and minimum sustain voltage and the improvement of the sustain discharge time lag resulted from a strong electric field that originated in the increase in the wall voltage.

Effects of Various Sustain Electrode Gaps on the Discharge Characteristics of an AC PDP With an Auxiliary Electrode

The effects of sustain electrode gap variation on discharge characteristics were investigated in an ac plasma display panel (PDP) with an auxiliary electrode. In this experiment, the following variations were used for the sustain electrode gap of the PDP with an auxiliary electrode: 120, 140, 170, and 200 mum. Static margin, IR intensity, luminance, and power density were measured and investigated in relation to the sustain electrode gap variation. In all the various sustain electrode gaps, when a proper pulse is applied to an auxiliary electrode, luminous efficacy exceeds the levels achieved in the case of a floated auxiliary electrode. In the case of the shorter sustain electrode gaps of 120 and 140 mum, the improved luminous efficacy is mostly due to an increase in luminance. In the case of the longer sustain electrode gaps of 170 and 200 mum, the improved luminous efficacy is mostly due to a decrease in power density. As the sustain electrode gap increases, the operating sustain voltage becomes higher. On the other hand, the luminous efficacy increases when a proper pulse is applied to the auxiliary electrode.

Analysis of the driving characteristics for an ACPDP with an auxiliary electrode using the voltage-transfer closed surface

— The driving characteristics and wall-charge model of an ac plasma-display panel (ACPDP) with an auxiliary electrode were investigated by using voltage-transfer closed-surface modeling. To understand the wall-charge behavior of an ACPDP with an auxiliary electrode qualitatively, voltage-transfer closed-surface analysis was applied to a test panel under the full driving waveform. The voltage-transfer closed surfaces were obtained after the sustain, reset, and address periods, when the full-stage driving waveform was employed with the test panel. As a result, it was proven that the wall-charge model predicted in the previous work corresponded with the wall-charge behavior of an ACPDP with an auxiliary electrode. Also, based on the resultant form after the address period, the wall-charge model after the address period was recently added and the entire wall-charge model was completed in this work. In addition, by investigating the trajectory of the cell-state movement during the reset period, it was confirmed that the priming effect affected the reduced discharge time lag of an ACPDP with an auxiliary electrode under the newly proposed driving waveform for reducing address time lag.

P‐91: AC Plasma Display Panel with Gold Nano‐particles Inserted into an MgO Protective Layer

A modified MgO structure incorporating gold nano-particles is proposed in this work. By inserting gold nano-particles into the MgO protective layer, dozens of nanometer-scale bumps are created on its surface. The change in the morphology due to these bumps induces a higher secondary electron emission rate, which both increases the luminous efficacy and causes a 20 V reduction of the driving voltage.

P‐134: Dependency of Auxiliary Pulse Width on Luminous Efficacy in AC Plasma Display Panel

The width of the pulse applied to an auxiliary electrode was varied to investigate the characteristics of luminous efficacy of an AC plasma display with an auxiliary electrode in accordance with the frequency and duty factor of the sustain pulse. The auxiliary voltage margin increased with an increase in the sustain pulse width and a decrease in the auxiliary pulse width. In addition, the luminous efficacy increased with a decrease in the sustain pulse width and an increase in the auxiliary pulse width, except when the time interval between the auxiliary pulse and the subsequent sustain pulse is zero.