Development of newly Thin-film EL devices by AIST
The conventional fluorescent lamps in use today pose an environmental issue due to use of mercury in them leading the manufacturer to seek an alternative lighting with energy conservation in mind. Among the candidates are inorganic EL, organic EL and LEDs. The organic EL devices have several inherent issues namely the tradeoff between their light intensity and life span as their characteristics will degrade through exposure to air resulting in special sealing process which in turn leads to high material cost. The other candidate is white LED featuring high brightness but the known problems with white LEDs are their limited viewing angle being a point light source as well as limitation of resources such as gallium in making it which comes at a high cost. On the other hand inorganic EL devices using inorganic perovskite oxides having excellent chemical stability and heat resistance offer a promising lighting alternative. In addition inorganic EL devices are hardly degraded, and there is no limitation on resources. Based on this researchers at AIST (Advanced Industrial Science and Technology) in Japan has developed a thin film electroluminescent device using inorganic oxides.
The thin-film EL devices using perovskite oxides have long been used as capacitor material for electronic circuits. With an emission starting voltage of approximately 10 V AC, the power source can be downsized due to low voltage operation of the device. A wide viewing angle is obtained by means of plane emission through the entire surface of the transparent electrode. There are no resource constraints in regard to inorganic EL devices due to the global abundance of required materials for the emitting and insulator layers. All layers including the emitting layer are made of chemically stable inorganic materials. Furthermore, characteristic degradation due to oxidation or heat is unlikely to occur resulting in a simplified sealing process according to the institute. Applying this new technology in such applications as lighting, optical sources and display is still some years away until the higher brightness and polychromic radiation can be achieved.
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[...] optical application of perovskite materials, AIST has successfully developed a perovskite thin film electroluminescent device. Through this development AIST (Advanced Industrial Science and Technology) has obtained the [...]