One-pot Synthesis Of Core-shell Cu@M Nanosilks And The Application As Flexible Transparent Ohmic Electrode In Deep-UV Devices

Recently,optoelectronic devices such as LED,smart phones,and wearable intelligent devices have been widely used in our daily life,however,several unresolvedcritical problems still hinder their further development due to the limitation by traditional technology.One of them is the transparent electrodes(TEs),which plays an important role in the construction of optoelectronicdevices.Uptodate,TE materials for deep ultraviolet(DUV)region still rarely exist.Traditional electrode material,ITO,because of its scarcity,high cost and other issues,exploration for novel broad-spectrum TEs materials become the main target in the past decades.Cu nanowires(Cu NWs)have been regarded as the next generation of TEs due to their excellent performance and low cost.Nevertheless,Cu NWs still face some key challenges:stability,compatibility and expansibility.In view of these issues,our work in this thesis,three aspects were studied thoroughly,including the core-shell Cu silks(NSs)synthesis,the fabrication of Cu NSs based DUV LED(LED)and the other emerging applications with superfine CuNSs.We have developed several new techniques,and important approaches have heen achieved.Firstly,we proposed and achieved multi-metal coated Cu core-shell NSs synthesis technology and system.One-pot liquid phase method is employed to prepare superfine Cu@M(M=Ni,Zn,V,Ti,Ag,Pt)core-shell NSs with ultra-high aspect ratio(>1600)and ultra-smooth(<1 nm)surface.The fabricated core-shell Cu@M NSs TEs possessed excellent photoelectric properties(T ? 93%,Rs?50-90?sq-1,FOM?81-111),which are the best results ever reporte.With the precise controlling of the shell thickness via adjusting the reactants molar ratio,the antioxidant abilityof Cu@M NSs has been greatly improved even at extreme environments.Meanwhile,the outstanding mechanical stability of Cu@M NSs inbending,twisting and stretching experiments were completely demonstrated that the Cu@M NSs are able to satisfy the demands for intelligent flexible products.Secondly,we achieved thefabrication of fully transparent DUV-LED with Cu NSs based ohmic electrode.Importantly,the tunable work function of Cu@M NSs transparent electrodes were obtained by multi-metal shell coating technique.Then,a"copper foil capsule" annealing method was proposed for achieving ohmic type contact to high-aluminum component p-type Al0.46Ga0.54N with Cu@Ni NSs transparent electrodes.After this,we used MOCVD system to epitaxially grow p-GaN-free structure of DUV LED wafer,and fabricated the first fully transparent DUV-LED chips(285 nm)with Cu@Ni NSs TEs in the world.Ultimately,the DUV-LED chips on board was successfully lit with bright emission and possess excellent light transmission.To summarize,we have successfully solved the difficulty to achieve ohmic contact to high-aluminum component p-type AlGaN,and provide an original thinking to search promising TEs materials for deep ultraviolet devices.Thirdly,We accomplished the applications of Cu@M NSs in several intelligent flexible devices,such as LED dimmer,transparent anti-frost&defogger heater and colorfulintelligent conductive textile thread.(1)Based on the metal or alloy coated Cu NSs,a high elasticity,transparent,simple,stable,and environmental compatable LED dimmer film was fabricated via thepost treatment technology with acid and low temperature annealing.(2)The Cu@Ni NSs transparentanti-frost&defogger heaterfilm with high transmittance(>80%)was prepared.The Cu@Ni NSs transparent heater could operate in a low voltage(<5 V)and remove moisture within 90 seconds in a rapid heating model.Therefore this new transparentanti-frost&defogger heater could be widely appliedto defogging for automotive front windshield,intelligent clothing heating and other fields.(3)The Cu@Ag NSs conductive networks based colorful conductive textile threads were prepared by liquid-phase dipping method.The colorful conductive threads possess excellent transparency and electric conductivity of only 2 ?/cm.Furthermore,the colorful conductive threads were applied to intelligent lighting apparel and intelligent heating apparel successfully.The research achievements of this workprovide key technologies and data,which arises new concepts and methods for exploring of novel type of optoelectronic devices.