The use of laser diodes will make another breakthrough in the development of technologies such as
Long time organic laser diodesconsidered an unattainable goal in the field of light-emitting devices. They use organic materials to emit light instead of inorganic semiconductors, such as gallium arsenide and gallium nitride, used in traditional devices.
Laser diodes are a lot like organiclight-emitting diodes (OLED), in which a thin layer of organic molecules emits light when power is applied. OLED has become a popular choice for smartphone displays because of their high performance and vibrant colors that can be easily changed by creating new organic molecules.
Organic laser diodes produce muchcleaner light, but to achieve the generation process, currents are required, the magnitudes of which are higher than those used in LEDs. These extreme conditions led to the fact that the previously investigated devices failed long before the generation of radiation began.
Scientists from the Organic Photonics and Electronics Research Center at Kyushu University reported that they implemented organic semiconductor laser diodes.
"I think that many people in the scientific communitydoubted whether we would ever see the realization of an organic laser diode, ”says Atula S.D. Sandanayaka, lead author of the article. “But thanks to improved materials and new devices, we finally did it.”
An important step in generating is to feed a largethe amount of electrical current in the organic layers to achieve a state called population inversion. However, the high resistance of many organic materials makes it difficult to obtain a sufficient amount of electrical charges before the materials themselves heat up and burn.
On top of that, the various loss processes inherent in most organic materials and devices operating at high currents reduce efficiency, increasing the current required even higher.
To overcome these obstaclesThe research team used high-performance organic light-emitting material (BSBCz) with relatively low resistance to electricity and small losses - even with large amounts of electricity. But the right material alone was not enough.
Photo: Schematic representation of an organic semiconductor laser diode producing blue laser radiation when electrically excited.
They also developed a device design witha grid of insulating material on top of one of the electrodes used to supply electricity to thin organic films. It is known that such grids - the so-called distributed feedback structures - create the optical effects necessary for generation, but the researchers took another step forward.
“By optimizing these grids, we could not onlyto obtain the desired optical properties, but also to control the flow of electricity in the devices and minimize the amount of electricity needed to observe the generation from an organic thin film, ”says Adachi.
Researchers are so confident in the promise of theseThe new devices that founded the start-up company KOALA Tech Inc. to accelerate research and overcome the last obstacles remaining for the use of organic laser diodes in mass production.