CINNO Research Industry Information. Recently, scientists at Kyushu University in Japan combined thicker perovskite materials with other thinner organic layers by mixing to produce organic light-emitting diodes (micron-thickness) ( OLED). This design can reduce the cost of current high-performance TVs, and also has the potential to increase the viewing angle of various other displays.
In principle, OLED is a device that uses an organic molecular layer to efficiently convert electrical energy into light energy. Although these organic molecular layers are all very good light emitting materials, they are not very good conductors in terms of electrical properties. It is based on such problems that researchers hope to design a very thin layer (about 100 nanometers) to allow the applied current to easily reach the light emitting layer in the center of the device.
Although this very thin layer requires very little material, when developing and designing a product with an unlimited number of pixels, the problem becomes very complicated. After all, even very small defects can cause equipment problems. In addition, the two beams of light reflected from the back and front of the thin layer usually cause interference, which is known in the industry as the cavity effect. It is because of this cavity effect that the light with a large viewing angle starting from the OLED will be distorted to some extent.
Based on the above considerations, it is very difficult to develop a product with a thicker material without being affected by the cavity effect. To do this, researchers at Kyushu University designed and used a transparent and highly conductive perovskite material.
Toshinori Matsushima, principal researcher and associate professor at the International Institute of Carbon Neutral Energy at Kyushu University, said: "These perovskite materials, which are a mixture of organic and inorganic components, can be made from some inexpensive raw materials. Organic materials. This makes the perovskite materials perfectly match the traditional OLED organic materials. "
The scientists at Kyushu University deposited a dense layer of molecules in the light-emitting layer of the OLED device. These molecules are commonly used between perovskite layers in OLED devices, with a total thickness of 2,000 nm. The OLED device obtained in this way has an active layer that is 10 times thicker than a standard OLED device-although it is far less than the thickness of a human hair.
Based on the above design, the efficiency of OLED devices with thicker light-emitting layers is similar to that of traditional OLED devices with thinner active layers. In addition, the angular emission effect of these two OLED devices is also basically the same. However, in contrast, the above-mentioned OLED device with a thicker active layer cannot normally emit light under the operating voltage of a conventional OLED.
"These results overthrow the understanding of people for 30 years that OLEDs can only emit light based on thin films. At the same time, this has opened up a low cost, high reliability and better uniformity for the manufacture of OLED devices mainly used for display and lighting. Pathway, "said Professor Chihaya Adachi, director of the Center for Organic Photonics at the Institute of Electronics, Kyushu University.
Scientists have also tried to use perovskite directly as a light-emitting material, but so far, the life of OLED devices based on this design has been very short.
By using the perovskite layer material for current transmission and maintaining the light emission process of organic materials, the life span of this OLED device designed by the research team of Kyushu University has been close to that of traditional OLED devices.
"Based on this work, perovskite, a high-performance material, has demonstrated its versatility. It can not only support OLED devices to emit light, but also be used in other organic electronic devices such as lasers, storage devices, and sensors. Adachi predicted.