Recently, the research team of Professor Sun Hongbo and Associate Professor Lin Linhan from the Department of Precision Instruments of Tsinghua University proposed a new nano particle laser 3D printing technology, which uses a new printing principle and mechanism to endow 3D nano printing technology with more magical characteristics. This technology is expected to improve the VR display resolution, so that people can see a high-definition virtual reality world.
This achievement is entitled "Photoexcitation Induced Chemical Bonding to Realize 3D Nanoprinting of Semiconductor Quantum Dots", which was recently published in the journal Science.
Nanoscience and technology, as one of the hottest research fields in the 21st century, plays an important role in promoting the current integrated and intelligent development. The application of nanotechnology can be seen everywhere in advanced electronic equipment, biomedical detection and other fields.
Of course, the principle behind these frontier applications is based on a series of strange physical and chemical effects generated by the reduction of material size to nanometer scale, including quantum confinement effect and quantum tunneling effect in semiconductor materials, surface plasmon resonance in metal materials, etc. The preparation of existing nano devices is mainly based on micro nano manufacturing technologies such as photolithography and electron beam exposure, which is only applicable to a limited variety of nano materials. As a planar preparation process, it is difficult to achieve three-dimensional manufacturing of nano materials.
On the other hand, chemical synthesis can be used to achieve the preparation and precise cutting of colorful (different sizes, morphologies, compositions) nanoparticles, and these nanomaterials have high crystal quality, good surface quality, and superior optical, electrical, magnetic and other properties. However, these chemically synthesized nanoparticles lack effective device based preparation technology, which has become the technical bottleneck of their wide application.
In view of the above problems, the research team proposed a new principle of photo induced chemical bonding, realized the laser three-dimensional assembly technology of nanoparticles, and used various nanoparticles as raw materials to assemble three-dimensional nano devices. Taking semiconductor quantum dots with core-shell structure as an example, the laser excited quantum dots are used to generate electron hole pairs. Through energy level matching, the tunneling and surface migration of photogenerated holes are driven, which promotes the desorption of ligands on the surface of quantum dots and the formation of active chemical sites, thereby inducing chemical bonding on the surface of quantum dots and realizing efficient assembly between quantum dots.
It is reported that based on the above principles, the research team further focused and programmed the laser beam, and achieved the precision molding of the complex three-dimensional structure of nanomaterials.
"Compared with the existing micro/nano processing and preparation technology, this technology has distinctive features: first, the printing material has high purity, which breaks through the principle limitation of photopolymerization, does not need any optical bonding components, and realizes 3D printing of nearly 100% functional nano particle components; second, the 3D processing ability is strong, which can realize nano printing of multiple 3D structures such as complex linear, bending and volume structures, so as to construct new functional 3D optoelectronic devices ； Third, it has multi-component printing function, using quantum dots of different sizes as raw materials. This technology demonstrates the multi-component heterogeneous composite printing capability; Fourth, the printing resolution is high. The use of nonlinear light excitation makes the printing resolution break through the optical diffraction limit. The density of the printing point array exceeds 20,000 ppi, and the printing limit resolution reaches 77 nm, which helps to achieve ultra-high resolution display devices and promote the development of VR. " The relevant responsible person of the team said.
It is understood that the micro nano manufacturing principle of photo induced chemical bonding has a wide range of material and structural adaptability. Through energy level design, high-precision micro nano manufacturing of a variety of semiconductor and metal materials can be realized, which opens up a new way to prepare nano devices. It has important application prospects in the fields of on chip optoelectronic device integration, high-performance sensing materials, etc.
Source: Guangming Daily
