Liquid crystal displays, the dominant flat panel display technology, are limited in brightness and energy efficiency because of the use of absorbing polarizers and color filters. Liquid crystal-based photoluminescent display devices have been fabricated that use thin, polarized photoluminescent layers that have highly anisotropic absorption or emission. These layers both polarize light and generate bright color. This approach can simplify device design and substantially increase device brightness, contrast, efficiency, and (in specific configurations) viewing angle.

Nature © Macmillan Publishers Ltd 1998 8 letters to nature NATURE | VOL 392 | 19 MARCH 1998 261and get a glimpse of the structure of the proton excited states 29,30 . The results depicted in Fig. 4 as a function of pressure further strengthen our conclusions. Upon compressing ice VIII, we find that the protons become increasingly compact, ground-state dominated and thus localized. Overstepping the phase boundary to ice VII (long dashed line), their spatial extent increases rapidly and is accompanied by a strong delocalization: that is, extended protonic states contribute significantly in addition to the ground state. Such behaviour is also characteristic immediately after crossing the phase transition to ice X (short dashed line), but there is a clear trend for protons to become strongly localized again at the highest pressure, where the underlying potential is of the single-well type.Our essential findings can be summarized as follows: (1) The sequence of the transitions is antiferroelectric ice VIII to paraelectric ice VII and finally to symmetric ice X at about 100 K; (2) the isotope effect on the antiferroelectric disordering transition (VIII → VII) is caused by translational proton tunnelling, whereas that on symmetrization (VII → X) is a qualitative zero-point motion effect; and (3) there are two 'forms' of ice X, both characterized by a unimodal proton distribution centred at the bond midpoint, the one at lower pressure being characterized by an underlying double-well proton transfer potential and a very broad proton distribution, whereas the high-pressure form has a single-well potential with a sharper proton localization. We hope that the insight we have gained from the different regimes of a 'clean' and relatively simple system, ice under controlled high pressure, will be useful in understanding quantum effects in other proton-transfer systems. Ⅺ

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Photoluminescent polarizers that comprise uniaxially oriented photoluminescent species which absorb and emit light in highly linearly polarized fashion, can efficiently combine the polarization of light and the generation of bright colors. We here report the preparation and characterization of such polarizers by simple melt-processing and solid-state deformation of blends of a photoluminescent guest and a thermoplastic matrix polymer. The orientation behavior of a poly(2,5-dialkoxy-p-phenyleneethynylene) derivative (EHO-OPPE), 1,4-bis(phenylethynyl )benzene, and 1,4-bis(4-dodecyloxyphenylethynyl )benzene was systematically compared in different polyethylene grades. Experiments suggest that if phase-separation between the photoluminescent guest and the matrix polymer is reduced during the preparation of the pristine (i.e. unstretched) blend films, photoluminescent polarizers can be produced which exhibit unusually high dichroic properties at minimal draw ratios. In connection with this finding, an optimized, melt-processed blend based on 1,4-bis(4-dodecyloxyphenylethynyl )benzene and linear low-density polyethylene was developed that allows efficient manufacturing of photoluminescent polarizers which at draw ratios of only 10 exhibit dichroic ratios exceeding 50.