Research On Organic Light-emitting Devices Based On Ag Nanomesh Electrode Fabricated By Nanosphere Lithography

Over the past few decades,optoelectronic devices have entered the consumer electronics market in an unprecedented trend,revolutionizing the way people live.Recent years,Organic Light-Emitting Devices(OLEDs)have been rapidly adopted in the mobile and TV display markets due to its ultrahigh efficiency,large color gamut,lightweight,thinner,flexibility and enough lifetime.As an important component of OLEDs,Transparent Conductive Electrodes(TCEs)has always been a research hotspot in the field of optoelectronic devices.Both optical and electrical properties of OLEDs are affected by the conductivity and transmittance of TCEs.Tin-doped indium oxide(ITO)is usually chosen as the transparent conductive electrode of OLEDs,but ITO is not the best choice due to its high price due to insufficient indium reserves in the earth's crust.In addition,the high refractive index in ITO leads to waveguide mode light loss and reduces the light extraction efficiency of OLEDs.The transmittance of ultra-thin continuous metal film electrode is also affected by film thickness.Due to its excellent conductivity and good compatibility with organic materials,a metal thin film has been considered as one of the most promising candidates for TCEs.However,the inferior transmittance and surface plasmon-polariton(SPP)mode of the interface between the metal electrode and the organic layer will make part of the photons unable to be coupled out of the device lead to limitation of extraction efficiency.Therefore,it is necessary to improve the transmittance of metal film electrodes and reduce the SPP loss to improve the efficiency of OLEDs.This paper focuses on the research of metal conductive anode of OLEDs,and improves the performance of OLEDs by introducing nanomesh structure.Our work is mainly divided into the following two parts:1.Transparent ultra-thin silver(Ag)nanomesh electrode was prepared by nanosphere lithography technology combined with wetting layer.The electrode has simple structure and low cost.Compared with the continuous ultrathin Ag film electrode,the transmittance of the ultrathin Ag nanomesh electrode is obviously improved and the FOM of the ultrathin Ag nanomesh electrode is higher(3.01×10^-3?^-1)under the premise of high conductivity.Compared with traditional ITO anodes,the maximum luminance and current efficiency of OLEDs using ultra-thin Ag nanomesh electrodes have improved 56.2%and 41.4%respectively It is worth noting that the ultrathin Ag nanomesh electrode has been proved able to resolve the emission intensity roll-off of OLEDs with dual metal electrodes as the enlargement of viewing angle due to the redistribution of the light emission direction derived from strong scattering.2:We have prepared an Ag nanomesh electrode with subwavelength period,which is used to excite SPP resonance at the metal electrode/organic interface coupling into the photons to extract from the devices.We realized the manipulation of the SPP peak by adjusting the duty ratio of the nanomesh structure.In the future work,we would try to apply this nanomesh electrode to the OLEDs to clarify the effect on the extraction efficiency.