History of Electroluminescence

1907 - Electroluminescence was first observed in silicon carbide (SiC) by Captain Henry Joseph Round, Round was an employee of the Marconi Company and a personal assistant to Guglielmo Marconi. he reported that a yellow light was produced when a current was passed through a silicon carbide detector.

1923 - second reported observation of electroluminescence by O.V. Lossev. Again with silicon carbide.

Late 1920s - B. Gudden and R.W. Pohl conducted experiments in Germany with phosphors made from zinc sulfide doped with copper

1936 - Georges Destriau published a report on the emission of light from zinc sulfide powders after applying an electrical current. Destriau worked in the laboratories of Madame Marie Curie in Paris and first coined the word "electroluminescence" to refer to the phenomenon he observed.

1939-1945 - During World War II, a considerable amount of research was done on phosphors in connection with work on radar displays (which was later to benefit the television industry in the form of better cathode ray tubes).

1950 - GTE Sylvania fired various coatings, including EL phosphors onto heavy steel plates to create ceramic EL lamps. During this period, most research focused on powder EL phosphors to get bright lamps requiring minimal power and with a potentially long lifetime. Research funding was cut back when it was determined that product lifetimes were too short (approximately 500 hours).

Late 1950s - first thin-film EL structures were fabricated by Vlasenko and Popkov. These two scientists observed that luminance increased markedly in EL devices when they used a thin film of Zinc Sulfide doped with Manganese. Luminance was much higher in thin film EL (TFEL) devices than in those using powdered substances. Such devices however were still too unreliable for commercial use

Mid-1960s - There was a revival of EL research in the United States focused on display applications.

1968 - Aron Vecht first demonstrated a direct current (DC) powered EL panel using powdered phosphors.

1974 - Toshio Inoguchi and his colleagues at Sharp Corporation introduced an alternating current (AC) thin film EL approach to ELDs at the annual meeting of the Society for Information Display (SID).

1976 - Tektronix' research on EL began

1981 - Okamoto reported that a rare-earth doped ZnS could be used in the phosphor layer of a thin film EL device

1984 - William Barrow of Planar and his colleagues announced that they were able to get blue-green emissions from strontium sulphide doped with cerium.

1985 - Shosaku Tanaka at Tottori University and his colleagues managed to get calcium sulphide to emit a deep red colour.

1988 - Tanaka's group announced that they had gotten white light. The idea here was to use the white light in connection with a colour filter to produce a full colour display analogously to the way that it is done in liquid crystal displays. The advantage of doing this with ELDs was that such a display would not require a backlight. The main disadvantage was the added cost and difficulty of introducing a colour filter.

1994 - Soininen and coworkers at Planar International in Finland announced that a white phosphor deposited by atomic layer epitaxy achieves sufficient luminance and stability for use in colour EL display products.

1997 - Sey-Shing Sun of Planar reported a blue phosphor showing improved blue colour and efficiency.

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