Influence of gas mixture ratio on the luminous efficiency in surface discharge alternating current plasma display panels New combination of a three-component gas, Ne-Xe-Ar, for a high efficiency plasma display panelThe dependence of the efficacy of an alternating current surface-discharge plasma display panel on the gas pressure is investigated for several Xe-Ne gas mixtures. In monochrome green 4 in. test panels the efficacy trends and emission spectra are examined for increasing gas pressure and/or Xe concentration. The measured panel efficacy and emission characteristics are compared with the results of a numerical discharge model. It is found that the discharge efficiency for the cell geometry used in present-day commercial products can be increased significantly by using a larger Xe partial pressure. An increase of the electron heating efficiency and of the Xe excitation efficiency contribute about equally to the efficacy increase. The contribution of the increasing Xe dimer radiation fraction to the efficacy improvement is relatively small. These findings are applied in a 4 in. color test display with a design that resembles the one used in present-day commercial products and contains a gas mixture of 13.5% Xe in Ne at 800 hPa. For realistic operating conditions an efficacy of 3.8 lm/W at a white luminance of 2010 cd/m 2 is obtained. Furthermore, the panel chromaticity improves for increasing Xe partial pressure due to decreasing Ne emission.

The dependence of the panel efficacy of an alternating current-surface-discharge plasma display on the input power is investigated. Test panels with a design resembling the one used in main stream commercial products are used. The input power is varied in two ways: namely by changing the dielectric layer capacitance (thickness) and by changing the sustain voltage. An interesting different behavior is found: for increasing capacitance the efficacy decreases markedly, whereas for increasing sustain voltage the efficacy increases slightly. The different behavior is attributed to changes in the ion heating losses. It is found that plasma saturation, which implies a fundamental trade-off between luminance and efficacy, is not significant at practical input power values. A high luminance and a high efficacy are concurrent for a plasma panel design with a low dielectric layer capacitance and a high sustain voltage.

Transport studies of atomically thin 1T-TaS 2 have demonstrated the presence of intermediate resistance states across the nearly commensurate (NC) to commensurate (C) charge density wave (CDW) transition, which can be further switched electrically. While this presents exciting opportunities for memristor applications, the switching mechanism could be potentially attributed to the formation of inhomogeneous C and NC domains. Here, we present combined electrical driving and photocurrent imaging of ultrathin 1T-TaS 2 in a heterostructure geometry. While micron-sized CDW domains are seen upon cooling, electrically driven transitions are largely uniform, indicating that the latter likely induces true metastable CDW states, which we then explain by a free energy analysis. Additionally, we are able to perform repeatable and bidirectional switching across the intermediate states without changing sample temperature, demonstrating that atomically thin 1T-TaS 2 can be further used as a robust and reversible multimemristor material for the first time.

Plasma display panel emission measurements are correlated with panel efficacy trends, and directions for the improvement of the discharge efficiency are derived. An increase of the ratio of the phosphor emission in the visible to the Xe emission in the infrared indicates an increased Xe excitation efficiency. Also, the time dependence and the spatial distribution of the Xe emission are important discharge characteristics. Experiments reveal that a high panel efficacy is obtained, especially for design and driving conditions that govern a fast and spatially distributed discharge development. A high sustain voltage 200 V causes a "high efficiency discharge mode." It is proposed that in this mode, the cathode sheath is not, or is incompletely, formed during the rise of the discharge current. Then the electric field in the discharge cell is dominated not by the space charges, but by the externally applied voltage. The effective discharge field is lowered, resulting in a lower effective electron temperature and more efficient Xe-excitation. Under the fast discharge buildup conditions also the electron-heating efficiency increases due to a decrease of the ion heating losses in the cathode sheath. A high sustain voltage combines well with a high Xe content gas mixture, that further increases the discharge efficiency. Changes in the phosphor to Xeand Ne-emission ratio show that for higher Xe content, a lower electron temperature accounts for a more efficient Xe excitation. Further, the use of a TiO 2 -layer underneath the phosphor causes an increase of the ratio of the phosphor emission in the visible to the Xe emission in the infrared, i.e., an increased Xe excitation efficiency. As a result, a high efficacy of 5 lm/W and a high luminance of 5000 cd m 2 have been realized in a 4-in color plasma display test panel design with a 50% Xe in Ne gas mixture, a TiO 2 -layer underneath the phosphor, and a high sustain voltage 260-290 V.