The Research Of Flexible Transparent Electrode For OLED Devices Based On Nanomaterials

As the transparent flexible organic light emitting devices(OLED)converted from theory to real products,the techniques,products diversification will be significantly improved in future.The exploration of transparent flexible electrodes with stable performances has important scientific research value because electrode is one of the very important parts of the structure of OLED.This paper research the transparent flexible electrodes based on nanomaterials which can be used in OLED,mainly divided into three parts as follows.Firstly,ultraviolet(UV)radiation was used to modify the silver(Ag)anode in ordered to improve work function of the anode interface.This greatly reduced the hole-injection barrier,improved the ability of carrier injection.The influence of ultraviolet(UV)radiation time on performance of the OLED device based on the structure of Ag/N,N'-diphenyl-N,N '-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine(NPB)/8-hydroxyquinoline aluminum(Alq3)/Lithium fluoride(Li F)/Aluminum(Al)was researched.The results showed that UV radiation generated oxidation on Ag anode surface,this thin oxide layer effectively reduced the hole-injection barrier between Ag anode and the other functional layers,improved the performance of device.The modified Ag anode surface resistance was 1.8 ?/cm~2,work function was 5.17 eV,the interface reduced from 0.80 eV to 0.53 eV.Great performance improvement of green light OLED light-emitting device was obtained.The OLED device which anode was modified for 50 s by UV was the best,the turn-on voltage was reduced from 20 v to 6 v,the maximum brightness increased from 101.6 cd/m~2 to 5609.2 cd/m~2,current efficiency was improved also,and the luminescence peak position was not changed after the modification.That has a certain application prospect in improving the Ag anode transparent flexible OLED device performanceSecondly,double-side micro dimensions OLED devices were made with Al/LiF/Ag/MoO3/Ag,Al/LiF/Aurum(Au)and Al/LiF/Ag transparent anode structure instead of Al as OLED transparent cathode.The work function of Al/Li F modification also analyzed,the evaporation of Al and LiF thin layer after of Alq3 layer caused dissociative anion form ion drift,which continuously improved the ability of the cathode electron injection and electronic transmission ability.This can be use in the subsequent preparation transparent flexible three colors of white light OLED device.Thirdly,a simple spraying method was used to prepare the transparent conductive films(TCFs)based on Ag nanowires(AgNWs).Polyvinylpyrrolidone(PVP)was introduced to modify the interface of substrate.The transmittance and bending performance were improved by optimizing the number of spraying times and the solution concentration and controlling the annealing time.The transmittance of PVP/AgNWs films was 53.4 %—67.9 % at 380 nm—780 nm,and the sheet resistance was 30 ?/cm~2 which is equivalent to that of commercial indium tin oxide(ITO).During cyclic bending tests to 500 cycles with bending radius of 5 mm,the changes of resistivity were negligible.After 180 s of ultrasonic,the surface of membrane was still intact,maintain excellent conductivity.The performance of PVP/AgNWs transparent electrodes has little change after being exposed to the normal environment for 1000 h.The optimized film-inversion technology,greatly reduced the surface roughness.We can improve the performance of the OLED devices by introducing a modified layer in later work.