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Graphene + quantum dots, new hybrid materials will help next-generation display research
Researchers at the Indian Institute of Science (IISc) have created a novel hybrid of graphene and quantum dots, a breakthrough that may inspire research into the next generation of efficient and controllable displays and LED displays. Quantum dots are nanoscale semiconductor crystals that have the potential to revolutionize a variety of technologies, including photovoltaics, medical imaging, and quantum computing. Quantum dots can absorb ultraviolet light to produce clear and bright colors, which are especially suitable for the production of next-generation TV sets, smartphones and LED displays. However, they are not good electrical conductors and are therefore inefficient when used alone on equipment. To improve efficiency, the researchers tried combining them with graphene, an excellent conductor. The added graphene compensates for the product's ability to conduct electricity, even after manufacturing or turning the device on and off at will. While this combination would work well for photodetectors and sensors, it's practically useless for displays and LED displays because the quantum dots lose their ability to emit light when fused with graphene. By modifying some experimental conditions, IISc scientists have found a way to eliminate this effect and develop a highly tunable hybrid material. The results published by ACS Photonics open the door to a new generation of state-of-the-art displays and LEDs. Quantum dots are very small particles that perform far better than conventional semiconductors. When activated by UV light, they can produce different colors of visible light depending on their size. For example, small dots produce blue light, while larger ones emit red light. They absorb light well, but they are not good conductors of electricity, so devices based on quantum dots that convert light into electricity are not very efficient. In contrast, graphene is almost transparent to light, but it is an excellent electrical conductor. When the two are combined, graphene can theoretically quickly draw the energy absorbed by the quantum dots away from it, reducing energy loss and converting it into an electrical signal. This makes it possible to create extremely efficient devices such as photodetectors. Jaydeep Kumar Basu, professor of physics at IISc and first author of the paper, said:“Both are the best.”In the above case, the transfer of energy to graphene leaves the quantum dots with little energy left to emit light, making them unusable in displays or LEDs. Basu said:“Due to these effects, the application of these hybrid materials has not yet begun, and in the case of quantum dots, graphene acts like a sponge, not allowing any energy to be emitted.”Basu's team attempted to overcome this by exploiting a reaction known as superradiance“quench”effect. When a single atom or emitter (such as a quantum dot) in a layer is excited, each emits light independently. Under certain conditions, all atoms or emitters can cooperate to emit light. This produces a very bright light whose intensity is significantly greater than the sum of the emissions of the individual ones. In previous studies, Basu's team produced superradiance on a thin layer of quantum dots by combining with metal nanoparticles under certain experimental conditions. They reproduced these conditions in the new quantum dot-graphene hybrid material to generate ultra-strong radiation strong enough to counteract quenching. Using data models, they found that this happens when individual quantum dots are 5nm or less apart, and the quantum dot layer and graphene are separated by a distance of 3nm or less. Basu said:“We are the first to be able to eliminate this”sponge“effect and keep the signal source active. When superradiance dominated, the light emitted in the presence of graphene was three times as intense as what could be achieved with quantum dots alone. Basu said:“The advantage of graphene is that one can also tune it electronically. The intensity can be changed by simply changing the voltage or current.”The study also opens up new avenues for understanding how light and matter interact at the nanoscale, the authors say. The article comes from the phys website. The original title is Novel hybrid material may inspire highly efficient next-gen displays, which is compiled and organized by Materials Science and Technology Online.
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