Preparation Of Stable Quantum Dots And Investigation Of Their Corresponding Color Conversion Towards On Display Application

Light-emitting devices are prepared by combining QD with LED,which have a very broad prospect in the backlight field of liquid crystal displays.In the QD-on-chip structure,we need a small amount of QD materials.The QD-on-chip structure is suitable for cost-effective manufacturing.However,there are still some challenges.Poor QD stability is a problem.Oxygen and moisture are two key factors to affect the stability of QD.There are two ways to improve the stability and reliability of QD and QD-on-chip devices.One is to optimize the properties of QD,and the other is to optimize the properties of the UV-curing resin.Here,we proposed the QD core-shell design,silica encapsulation and ligand exchange strategies to enhance the reliability of QD against oxygen and moisture.Meanwhile,a highly reactive crosslinking agent can also be added to the UV-curing resin,which can increase the functional groups in the reaction in the UV-curing resin and improve the curing speed.It can reduce the permeability of oxygen and moisture to the UV-curing resin.Currently,with research and market demand for high quality displays on small areas.The appearance of micro light-emitting diode(Micro-LED)display technology has further expanded the application possibilities of display technology.Micro-LED has expanded the application possibility of QD display technology owing to their low power consumption,wide color gamut,long life,and short response time.Based on our chemically stable and photostable quantum dot materials prepared by surface modification and the technical methods to enhance the stability by using polymer compounding.Subsequently,the red and green patterned quantum dot films were realized by two micro-nano machining technology routes,quantum dot photoresist mixing and photoresist peeling.Detailed research contents are described as follows:(1)Firstly we synthesized the Cd Se/Cd S/Zn S core-shell quantum dots.For the synthesized Cd Se/Cd S/Zn S QD or Cd Se/Cd S QD samples mixed with UV-curing resin.The homogenous mixtures were acquired by stirring.Then we prepared the QD-on-chip devices by adding these mixtures dropped onto blue Ga N LED chips and solidified by UV light(365 nm).These QDon-chip structure devices were aged at 20 m A and ambient conditions.After 96 hours of aging,the light conversion efficiency of the Cd Se/Cd S/Zn S QD LED devices decayed 19.3% and the Cd Se/Cd S QD LED devices decayed 28.6%.(2)We converted the oleylamine capped QD to tetradecylphosphonic acid capped QD.Then pristine QD or the ligand-exchanged QD samples are mixed with UV-curing resin.The homogenous mixtures were acquired by stirring.Then we prepared the QD-on-chip devices by adding these mixtures dropped onto blue Ga N LED chips and solidified by UV light(365 nm).These QD-on-chip structure devices were aged at 20 m A and ambient conditions.After 288 hours of aging,The light conversion efficiency of the original QD LED devices attenuated 82%.The light conversion efficiency of the QD-TDPA LED devices attenuated 31%.The light conversion efficiency of QD-TDPA LED devices and a highly reactive cross-linking agent can also be added to the UV-curing resin decayed 28%.(3)In the process of preparing quantum dot pixel patterns using QD photoresist peeling,we formulated a series of different QD inks.This includes adding organic polymers to the ink,using two solvents in the ink,using different photoresist,and then we show the obtained QD pixel pattern,achieving a pixel size tunable from 5 μm to 100 μm.We obtained pixel patterns of 10 μm,50 μm,and 100 μm sizes in the QD photoresist co-blending system.The OD values of RQD and GQD films at 450 nm were 2.87 and 3.01.