JPS5854583A - Electric field light emitting element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electroluminescent device, and specifically relates to the structure of an insulating layer.

Conventional Example FIG. 1 is a sectional view of a main part of a conventional electroluminescent device, in which a light-emitting layer 1, which is a display medium, is placed in the first . They are supported on a glass substrate 6 by being sandwiched between a second insulating layer 2.3, and further sandwiched between an electrode 4 shaped according to the purpose of use and a metal back electrode 5 which functions as a reflective surface. It has become. In addition, 7 is a moisture-proof protective layer formed around the display surface side.

The electroluminescence is controlled by the voltage applied to display and illumination.

By the way, in such a configuration, in order to excite the luminescent center in the luminescent layer 1 and obtain luminescence with sufficient brightness, it is necessary to apply a considerable voltage between the electrodes 3 and 4, as shown by the broken line in FIG. 83. However, it had the drawback of having a high so-called light emission threshold voltage. Therefore, the power consumption is large and the circuit configuration is not easy, which poses a big problem in putting it into practical use.

This invention was made to solve the above-mentioned conventional problem, and includes a layer of one of the elements of group IV b of the periodic table of elements or any compound thereof between the second insulating layer and the light emitting layer. It is an object of the present invention to provide an electroluminescent element having a low emission threshold voltage at which luminescent centers in the luminescent layer are excited and start electroluminescence.

This invention will be explained in detail below.

Embodiment FIG. 2 is a sectional view of essential parts of an embodiment of the electroluminescent device of the present invention, in which 10 is a transparent glass substrate, and 11 is an electrode material on the glass substrate 10 depending on the purpose of use such as display or illumination. ITO was formed into a film with a thickness of 200 OA by electron beam heating evaporation method, a pattern was determined by dry etching, and heat treatment was performed.
The first insulating layer 13 is formed by electron beam thermal evaporation to a thickness of 300 OA, and the first insulating layer 13 is a Z, S thin film doped with anion as an active material to form a luminescent center on the first insulating layer 12.
14 is a light-emitting layer formed by electron beam heating evaporation to a thickness of 10A and then subjected to heat treatment.
15 is a Ge layer formed by electron beam heating evaporation to a thickness of 3000^, and Y2O is formed on the α layer 14 to a thickness of 3000^. J6 is a second insulating layer formed by electron beam heating evaporation. 2 A metal back electrode formed by depositing M to a thickness of 300 OA on the insulating layer 15 by electron beam heating vapor deposition; 17 is the transparent electrode 1;
1. First insulating layer 12, light emitting layer 13, Ge layer 14, second insulating layer 15. Sj O2 that isolates the rear substrate 16 from the outside air
This is a moisture-proof protective layer formed by electron beam heating to a thickness of 5000^.

In this configuration, when a voltage is applied between the electrodes 11.16, the luminescent center in the light emitting layer 13 interposed between the electrodes 11.16 is excited and emits yellow electroluminescence, and this light beam is emitted directly or from behind. The light is reflected by the electrodes 16 and irradiated to the user M side through the glass substrate 10, so that illumination and display operations can be obtained depending on the shape of the electrodes 11 and 16.

Moreover, when carriers are effectively injected into the light-emitting layer 13 by the Ca layer 14, the light-emitting center in the light-emitting layer 13 is excited and starts electroluminescence, as shown by the solid line B in FIG. The voltage between the electrodes 11 and 16, the so-called light emission threshold voltage, is lower than that of the conventional one.

Since the present invention has the above-described structure and function, (1) the light emission threshold voltage is lower than that of conventional elements, so power consumption is reduced when illumination or display operations are performed at low brightness; is smaller than that of the conventional one, and the driving circuit configuration can still be simplified, making it easy to put it into practical use as a commercial product.

(2) When used as a device for displaying characters, symbols, etc., getl or other
By providing wrinkles, the back surface of the light-emitting layer is blackened, increasing the absorption of external light entering from the front glass plate and increasing the contrast ratio with the electroluminescence of the light-emitting layer. Good display operation cannot be obtained even under bright conditions. (3) When driven at high voltage, the brightness is lower than conventional elements, but the increase in contrast ratio compensates for the decrease in illumination efficiency and display ability. Therefore, the desired function can be obtained, and there is no inconvenience during normal use, and performance sufficient for practical use can be obtained.

This will greatly contribute to the realization and widespread use of electroluminescent elements that can be driven at relatively low voltages and have good illumination display performance.

In the above embodiments, the case where Ge is used in the layer provided between the light emitting layer and the second insulating layer is described, but it is also possible to use one of the elements of group TVb of the periodic table of elements such as S or a compound thereof. However, you can expect to get the same effect as above.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a conventional electroluminescent device, FIG. 2 is a sectional view of a main part of an embodiment of an electroluminescent device of the present invention, and FIG. 3 is a sectional view of an essential part of a conventional electroluminescent device and an embodiment of the present invention. It is a figure which shows the measurement data of the applied voltage-luminance characteristic in a light emitting element. 10 glass substrate 11: transparent electrode 12: first insulating layer 13: light emitting layer 14: Ge layer 15: second insulating layer 16:
Back electrode I7: Moisture-proof protective layer 11 Figure M Figure 2 V Figure 3 RP application/i EV)

Claims (1)

[Claims] The light emitting layer is the first layer. In an electroluminescent element having a structure in which the electroluminescent element is sandwiched between a second insulating layer, a transparent electrode and a back electrode, and these are supported by a binding e-base, an element is provided between the light emitting layer and the second insulating layer. An electroluminescent device comprising a layer made of one of the elements of the yb group of the periodic table or a compound thereof.