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Research On High Efficiency White LED Based On Quantum Well/quantum Dot Resonance Energy Transfer Mechanism

Posted on:2018-08-31Degree:MasterType:Thesis
Country:ChinaCandidate:Y LiuFull Text:PDF
GTID:2358330518952617Subject:Integrated circuit engineering
Abstract/Summary:PDF Full Text Request
Recently white light-emitting-diode(LED)-based solid-state lighting is commanding much attention worldwide for its promise of energy savings.The predominant white LED technology under investigation involves the employment of high quantum efficiency blue GaN LEDs and down conversion of blue radiation to yellow/green and red for white light generation by phosphor.However,a number of limits on the performance of those white LEDs due to the phosphor-conversion scheme employed,such as short lifetime,low energy tranfer efficiency etc..In this paper,we fabricate five kinds of white light LED with different structures,which are respectively fluorescent powder coating;a mixed coating of green,yellow and red quantum dots;a mixed coating of green and red quantum dots with yellow fluorescent powder;the coating with quantum dots applied over fluorescent powder;the coating with fluorescent powder applied over quantum dots.With green,yellow,and red light quantum dots of CdSe/ZnS,YAG yellow fluorescent powder as light transformation materials and InGaN blue LED chip as the excitation light source,we finish the experiment.Through analysis and comparison,it is concluded that the white light LED with the structure of the coating with quantum dots applied over fluorescent powder,at the same time,with the proportion by weight of(green dots:yellow fluorescent powder:red quantum dots)stipulated at 5:2:1,which color rendering index is up to 88,the Luminous efficacy is 113.5 lm/W.It is relatively optimum surface coating type of white light LED.Secondly,in this paper,on the basis of fluorescence resonance energy transfer between InGaN quantum well and CdSe/(Zn,Cd)S quantum dots,we fabricate the quantum dot white light LED of Nanopore arrays type.We fabricate Lloyd exposure Interferometry technology and ICP Dry etching technique to prepare the nanopore arrays with the Aperture of 250nm and cycle of 250nm,on the Epitaxial Wafer surface of GaN based blue light LED,in which we spin coated quantum dots solutions of different concentrations and proportion,then get the quantum dot white light LED of Nanopore arrays type.The experimental results show that when the rate of quantum dots is the optimal proportion of green,yellow,red = 5:2:1,the optimal luminous efficacy of prepared white LED light is 93 lm/W,the Chromaticity Coordinates of(0.3681,0.3547),color temperature for 4203K which is close to the natural light color temperature,color rendering index up to the maximum of 91.7 that are much higher than the color rendering index of common fluorescence white light LED(<75),which has reached the level of good quality.It will provide a powerful push to the application of quantum dot white LED in the display back light field,and improve the application of quantum dots as fluorescence transformation materials in white light LED.
Keywords/Search Tags:Quantum dot LED, fluorescence resonance energy transfer, White LED, Quantum dot, Quantum well
PDF Full Text Request
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