Segmented Flow for a Continuous Flow Microwave Reactor

Technology Description

This invention is a continuous, segmented flow reactor system and method for the production of high quality NCs with microwave radiation. The system for NCs synthesis consists of an NC precursor configured to include an NC precursor solution with the ability to include a microwave reactor, segmentation fluid source, or other configurations depending on the nature of the application. The method for synthesizing NCs includes the step of providing and then segmenting the NC precursor solution with an immiscible segmentation fluid. The segmented NCs precursor solution is then continuously flowed through the microwave zone where it can be irradiated to produce NCs, which can be further processed in a growth zone. These continuous flow reactors (CFRs) This invention is unique in introducing a segmentation fluid prior to the microwave reaction zone. Segmentation results in recirculation of the solution in the microwave reaction zone, which minimizes material depositions in passageway side walls and tubing, as well as the resistive forces responsible for reducing fluid velocity near the walls. Thus the system and methods presented reduce the magnitude and variability in nanoparticle residence time, as well as increase uniformity in the size, shape, and composition of the product.

Features & Benefits

• Reduce cost per mass of NCs
• Reduce variability in size and quality of NCs
• Increased quality of production increases applicability in downstream applications

Applications

• Light emitting diodes
• Lasers - easily managed economic optical amplification media
• Quantum dots - for example consumer products utilizing semiconductor quantum dots (QDs) in displays (to improve efficiency and color gamut) - more scalable synthetic techniques (than the injection process) are desired at the industrial production scale to make these products more cost affordable
• Solar cells - semiconducting materials displaying photovoltaic effect

Background of Invention

As the demand of, and applications for Colloidal nanocrystals (NCs) increase, the development of low-cost processing systems that do not compromise nanocrystal quality become critical. Additionally important is the ability to limit variability in the shape, size, composition, and crystal structure of NCs. Generally high quality NCs are synthesized through the thermal decomposition of a mixture of molecules, specifically a “hot injection” method characterized by burst nucleation. This process is inefficient at a commercial scale due to the inability to control vessel temperature and mass transfer, two critical factors to maintaining optimal throughput (and reducing NC production time and cost). Continuous flow microwave reactor systems have highly controllable reaction conditions and thus can be used for large scale NC production. Although microwaves can direct energy input and uniformly heat the solution (eliminating problematic thermal gradients present in the hot injection method), deposition and early precipitation of the NCs in the microwave zone can result in unstable reaction conditions and sparking inside the microwave flow path. This invention eliminates the risk of catastrophic failure through sparking and increases efficiency in NC production cost and quality by the minimization of the material deposition in the reactor.

Status

U.S. Patent Application No. 14/582,514