The use of laser diodes will make it possible to make another breakthrough in the development of technologies such as
Long time organic laser diodeswere considered 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 similar to organic diodes in many ways.Light emitting diodes (OLED), in which a thin layer of organic molecules emits light when electrical power is applied. OLEDs have become a popular choice for smartphone displays due to their high efficiency and vibrant colors that can be easily modified by creating new organic molecules.
Organic laser diodes produce much morepurer light, but to achieve the generation process requires currents higher than those used in LEDs. These extreme conditions caused previously studied devices to fail long before radiation began to be generated.
Scientists from the Organic Photonics and Electronics Research Center at Kyushu University reported that they have realized organic semiconductor laser diodes.
"I think many people in the scientific communitydoubted whether we would ever see the implementation of an organic laser diode, says Atula S. D. Sandanayaka, lead author of the paper. “But thanks to improved materials and new devices, we finally did it.”
An important step in generation is the supply of largeamount of electric current into the organic layers to achieve a state called population inversion. However, the high resistance of many organic materials makes it difficult to generate enough electrical charges before the materials themselves heat up and burn.
On top of this, various loss processes inherent in most organic materials and devices operating at high currents reduce efficiency, raising the required current 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 over one of the electrodes used to deliver electricity to the thin organic films. Such grids—called distributed feedback structures—are known to produce the optical effects needed for lasing, but the researchers took it one step further.
“By optimizing these meshes, we were able to not onlyobtain the desired optical properties, but also control the flow of electricity in the devices and minimize the amount of electricity needed to observe lasing 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.