Research On Microcavity Adjustment And View Angle Of High Color Gamut Blue OLED Device

In recent years,OLED display with self-illuminated,thin,high contrast,fast response time,bending and other advantages,has caused extensive research and attention within the industry.High color gamut display is an important direction for the future development of the display industry,the larger the color gamut,the richer the display pieces can be rendered in color.High color gamut displays require light-emitting devices with narrower light-emitting spectra,while the electroluminescent spectrum of organic light-emitting materials is generally greater than 40 nm,hindering the development of OLED displays to high color gamut displays.Based on the above problems,this thesis designs the top light-emitting blue light-emitting device.Reasonable regulation of the internal microcavity effect of the device to narrow the spectrum to make it close to the CIE color coordinates of the BT.2020 high color gamut display,and at the same time to explore the changing laws of the device.1.Based on the TTA blue fluorescence light-emitting system,the design and preparation of the bottom light-emitting device and the top light-emitting device,and preliminary investigation of the top light-emitting device performance.By experiment: the bottom light-emitting device light-emitting peak wavelength is located at 458 nm,half-peak width of 44nm;and the top light-emitting device due to the role of the microcavity effect,the light-emitting peak wavelength is located at 461 nm,half-peak width of 22 nm,the spectrum is effectively narrowed,but the top light-emitting device there is a blue shift in the peak wavelength with increasing angle and diminishing brightness of the problem.2.To regulate the microcavity thickness and microcavity order of the device by taking advantage of the fact that the cavity transfer rate in organic materials is much larger than the electron transfer rate.Experimentally,it was found that: the thickness of the microcavity increases,which causes the spectral redshift of the device,and the color coordinates and half-peak width of the device also change;the spectral narrowing ability of the third-order microcavity device is stronger than that of the second-order microcavity device,and it is easier to obtain the dark blue coordinates at the same wavelength,but the electrical properties and viewing angle of the third-order microcavity device are poor,which is not suitable for practical application.A second-order microcavity device with a cavity transport layer thickness of 110 nm was selected as more suitable for the application.3.To investigate the effect of cathode thickness on the device by changing the cathode thickness based on the second-order microcavity device.The greater the cathode thickness,the smaller the device CIE-y,while the efficiency of the device also decreases as the cathode thickness increases.When the cathode thickness is 11 nm,the CIE color coordinates of the device reach(0.1410,0.0445),closest to the blue CIE color coordinates(0.131,0.046)required for the BT.2020 high color gamut display.4.To study the effect of capping layer on device characteristics.By preparing devices with different capping layer thickness and combining the top transmittance of the device for analysis,it is obtained that: the change of optical layer thickness will cause the top transmittance of the device to change,and the increase of transmittance will reduce the microcavity effect of the device,so that the viewing angle problem can be improved,while the decrease of transmittance will enhance the microcavity effect of the device,so that the viewing angle problem can be aggravated.When the capping thickness is 40 nm,the transmittance at the top of the device is maximum and the color shift at each viewing angle is minimum.