| With the shift of semiconductor industry focus and the limitation of traditional fluorescent materials,exploring new fluorescent materials has become the key to the rise of China’s semiconductor industry and enhance China’s core technology competitiveness.As a novel semiconductor fluorescent material,quantum dots(QDs)have excellent properties,such as narrow and tunable emission spectrum,wide absorption spectrum and high light conversion efficiency.These outstanding properties have shown them to be promising prospects of applications in optoelectronics or other related fields,and attract more and more attention from academia.However,traditional high-quality QDs are usually based on small-capacity milliliters and batch preparation,resulting in uneven reaction temperature and poor manipulation,poor preparation stability and repeatability,low production efficiency per unit time and high cost,which has become a bottleneck restricting the rapid and mass production of high-quality quantum dots.Therefore,how to design and fabricate a preparation reactor that facilitates the synthesis of high-quality QDs is crucial.To address these issues,a functional structure composite microreactor is proposed to synthesize QDs,which can realize rapid,efficient and large-scale preparation.The realization of these functions depende on the design and fabrication of functional structures in the reaction process.In this thesis,structure design,fabrication and function mechanism of microchannel were symmetrically studied.The main research contents and conclusions are summarized as follows:(1)Design and fabrication of the flow field structure of microreactorAiming at the heat transfer performance requirements of microchannel,a heat transfer type microchannel was designed.The microchannel flow field structure was optimized.The theoretical calculation method of flow field structure equivalent resistance network model and flow rate uniformity evaluation strategy were proposed.The accuracy of the theoretical model was verified by the finite element simulation method.The influence of microchannel geometry parameters on the velocity distribution was systematically analyzed,and the function mechanism of microchannel flow field structure on flow velocity uniformity is revealed.The advantages and disadvantages of microchannel and porous structure materials and machining properties were comprehensively compared,and the reasonable processing process route of microchannel and the forming scheme of porous functional structure were made.(2)Microreactor design and function mechanism for CQDsBased on the optimized results of microchannel theory calculation,three kinds of microchannels with linear-like,double-snake-like and snake-like shapes were designed to study the effects of different flow field structures on the performance of CQDs.The distributions of velocity,pressure and temperature in different flow structures were studied by finite element method.In addition,the function mechanism of three microreactors on CQDs was explored.The effects of key process parameters such as flow rate,reaction temperature and surface modification on the performance of CQDs were systematically studied.The qualitative analysis of CQDs was carried out based on spectroscopy and microscopy,and the differences of material structure and formation mechanism of CQDs prepared by microreactor with different flow field structures were revealed.(3)Porous structure microreactor design and function mechanism for CQDsThe method of preparing high-efficiency CQDs by metal fiber and foam copper porous structure composite microreactor was proposed for the first time.The microchannel reaction system and testing platform were constructed.The effects of porosity,flow velocity,reaction temperature and other parameters on the morphology and optical properties of CQDs were systematically analyzed.Additionally,the effects of surface morphology of porous functional structure and the fluorescence efficiency of CQDs prepared with or without porous functional structure were studied.The material composition and surface state of CQDs were deeply analyzed by using Transmission Electron Microscopy and Fourier Transform Infrared Spectroscopy.(4)Ultrasound/microreactor composite design and function mechanism for perovskite QDsAiming at the hybrid performance requirements of microchannels,a typical multi-bend snake-like microchannel was analyzed,and the influence mechanism of key parameters on the hybrid performance of microchannels was studied by simulation method.In the process of preparation,sonication was introduced to effectively control the directional growth of perovskite by using the cavitation and thermal effects of ultrasound,and to realize the crossscale morphology control of perovskite.In addition,the energy bandgap and optical properties of the perovskite QDs are tailored stepwise by ultrasonic and microreactor to realize the full spectrum preparation of perovskite QDs.Aiming at the problems that perovskite QDs are easily degraded,traditional solvents are highly toxic and the preparation cost is high,the preparation method of perovskite QDs using polymer coating and green non-polar solvents was proposed to achieve green,low-cost preparation.This method significantly improves their stability and lays the foundation for large-scale production and application of perovskite QDs.(5)Application of novel QDs in optoelectronicsThe applications of CQDs and perovskite QDs in optoelectronics were mainly studied.White-light CQDs were combined with ultraviolet light emitting-diode(LED)chips to optimize the relevant parameters so as to obtain white-light LED devices with high CRI.In addition,the green perovskite QDs film,red phosphor film and blue LED chip were combined to obtain WLEDs.The packaging structure was optimized.The maximum luminous efficiency of WLEDs is 62.9 lm/W with good operation and current stability... |
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