Flat-panel electronic displays: a triumph of physics, chemistry and engineering

Abstract

This paper describes the history and science behind the development of modern flat-panel displays, and assesses future trends. Electronic displays are an important feature of modern life. For many years the cathode ray tube, an engineering marvel, was universal, but its shape was cumbersome and its operating voltage too high. The need for a flat-panel display, working at a low voltage, became imperative, and much research has been applied to this need. Any versatile flat-panel display will exploit an electro-optical effect, a transparent conductor and an addressing system to deliver data locally. The first need is to convert an electrical signal into a visible change. Two methods are available, the first giving emission of light, the second modulating ambient illumination. The most useful light-emitting media are semiconductors, historically exploiting III–V or II–VI compounds, but more recently organic or polymer semiconductors. Another possible effect uses gas plasma discharges. The modulating, or subtractive, effects that have been studied include liquid crystals, electrophoresis, electrowetting and electrochromism.A transparent conductor makes it possible to apply a voltage to an extended area while observing the results. The design is a compromise, since the free electrons that carry current also absorb light. The first materials used were metals, but some semiconductors, when heavily doped, give a better balance, with high transmission for a low resistance. Delivering data unambiguously to a million or so picture elements across the display area is no easy task. The preferred solution is an amorphous silicon thin-film transistor deposited at each cross-point in an X–Y matrix.Success in these endeavours has led to many applications for flat-panel displays, including television, flexible displays, electronic paper, electronic books and advertising signs.

Sensitization of LnIII (Ln = Eu, Tb, Tm) Ion Luminescence by Functionalized Polycarbonate‐Based Materials and White Light Generation

“…Similarly, the T g values of the Eu III and Tb III systems of the BEP polymer shift to -7 and -8°C, respectively, from -32°C (Figure 4b). By contrast, Lu and co-workers [14] observed a decrease in the T g values of the PC films following coordination of Pr III ions, while Forster and coworkers [36] observed a decrease in the T g values of PC films doped with a [Eu(tta) 3 (H 2 O) 2 ] complex. We have attribute the decrease in the T g values observed in our polymers to the Ln III complexes acting as a plasticizer, as seen also by Lu, Forster and co-workers.…”

“…The BEP polymer is thus a better -centered emission than the BDP polymer; this lower efficiency of sensitized emission is further corroborated by the presence of f-f transitions in the excitation spectrum of the Eu III system of BDP ( Figure 7). [6] Despite similar 3 T energies of the polymers, only the BEP polymer is capable of sensitizing blue Tm III -centered emission, as can be seen from the band at 475 nm in Figure 8, corresponding to the 1 G 4 → 1 H 6 transition. [38] Recently, our group reported the first example of a metallopolymer with norbornene-based backbone and pyridine-2,6-bis(oxazoline) pendants that sensitized blue Tm III -centered emission in the solid-state.…”

“…Current displays based on organic light-emitting diodes use organic compounds, [1] metal complexes, [2] polymeric materials [1] and semiconductor materials [3] as the emissive layers. However, these emitting materials have reduced color purity due to vibrational broadening of their emission spectra, low emission efficiencies, difficulty in controlling the phase purity and size of the semiconducting materials, and a lack of long-term stability caused by photo-bleaching.…”

Synthesis and Photoluminescence Properties of HEu<SUB>1-<I>x</I></SUB>Gd<SUB><I>x</I></SUB>(MoO<SUB>4</SUB>)<SUB>2</SUB> Nanophosphor

“…Such transparent displays have been demonstrated mainly in the field of organic light-emitting devices [7]. In addition, stable low-scattering suspensions of inorganic phosphors in organic solvents have to be developed to improve the durability of flexible and transparent displays [8], [9]. However, almost all inorganic phosphors with high luminescence efficiency contain micron-sized particles, which have strong scattering characteristics.…”

Rising in the east: ‘The Liquid Crystal Display Story’, edited by N. Koide

“…That book is a fascinating read, because Castellano brings stories and science together with the flourish permitted through personal memories. Those looking for further insight into the Liquid Crystal story and its part in the flat-panel display revolution may then turn to David Dunmur and Tim SluckinÕs Soap, Science, and Flat-screen TVs: a history of liquid crystals [2], or Cyril HilsumÕs review in Philosophical Transactions [3]. My personal favourite account of the industry hereto has been Hirohisa KawamotoÕs review [4], particularly for its in depth scientific perspective but also for its history taken from a Japanese perspective.…”