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Research On The Plasmon Resonance Enhanced Blue Organic Light Emitting Diode And The Working Mechanism Of It

Posted on:2017-05-02Degree:MasterType:Thesis
Country:ChinaCandidate:H W ZhouFull Text:PDF
GTID:2308330488464630Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Organic light-emitting diodes(OLEDs) have many advantages, such as high brightness, fast response, low energy consumption, soft colors, light weight, flexible, low cost, OLEDs have great potential applications in flat panel displays, solid state lighting and other fields and it is one of the topics with much concern in the 21 st century of photoelectric information technology. In order to further promote the OLED industry, its efficiency and life still need to be improved.Surface plasmon(SP) is an electromagnetic oscillations in the local metal surface, when the surface plasma resonance happen, the electric field of the metal surface can be enhanced and it can also enhance the spontaneous emission rate of fluorescent molecules which near the surface plasmon, so, the efficiency of the fluorescence can be enhanced. Since the localized surface plasmon(LSP) which produced by metal nanoparticles has many advantages, such as the simple preparation process, easy to control, low cost, so, it is widely used in optimization studies of OLED performance. However, the trapping effect of metal material make the metal nanoparticle face enormous challenges when it is applied in OLED research. In this paper, the plasmon resonance effect and trapping effect on the performance of the OLED’s influence when metal nanoparticles were introduced into the blue OLED were studied, and the working mechanism of metal nanoparticles were also studied.Firstly, the OLEDs with solution process were prepared in this paper. The influence of the annealing temperature of the light-emitting layer, the host, the guest material and the mixing ratio of them, the thickness of the charge transport layers on the performance of devices were studied. The light-emitting layer and the structure of charge transport layers were designed and the performance of the solution processed OLED were optimized. The efficiency of the optimized yellow and blue OLEDs reached 50 cd/A and 40 cd/A respectively.Then, the silver nanoparticles(SNPs) were introduced in the electron transport layer of the blue OLED by using thermal evaporation method. The influence of the local surface plasmon resonance effect and the trapping effect of the silver nanoparticles on device performance were studied. The results shows that the trapping effect of the silver nanoparticles is very seriously, which greatly reduces the current density of the devices. So, in this paper, the size of the SNPs was firstly adjusted to reduce the trapping effect. Then, this paper focuses on the effect of SNPs on the performance of OLEDs when silver nanoparticles were located in different positions in the electron transport layer: 1) When SNPs near the light-emitting layer, although the plasmon resonance is strong, the performance of the devices decreased significantly due to the trapping effect; 2) When SNPs near the cathode, the penetration of silver atoms into the electron transport layer provide an injection channel for electron, at the same time, the local electric field near the cathode is enhanced by the plasma resonance effect, which is conducive to electron injection. By optimizing the location of the SNPs, the current, brightness and efficiency of blue OLEDs are enhanced.
Keywords/Search Tags:Organic light-emitting diode, Surface plasmon, silver nanoparticles, surface plasma resonance, trapping effect
PDF Full Text Request
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