Fabrication And Doping Of NiO Nanocrystals

The compositional regulation of nanocrystal has a great effect on the change of its properties.The doped nanocrystals have a great difference in performance compared to undoped ones.Therefore,it is important to develop an efficient systhesis method for nanocrystal doping.In this paper,nickel oxide nanocrystals were synthesized by the solution method,including "one-pot" method,"hot-injection"method and seed method.Meanwhile,the properties of synthesized nickel oxide nanocrystals were investigated.We studied doping and corresponding changes to properties of NiO nanocrystals.The main results are summarized following:1.The size and morphology of NiO nanocrystals can be controllled by adjusting the precursor and temperature during systhesis.Monodisperse spheroidal(2-5 nm)and nano-flower(15-20 nm)NiO nanocrystal can be obtained via an "one-pot"approach by using nickel stearate(NiSt)or nickel acetate tetrahydrate(Ni(Ac)2·4H2O)as precursors,respectively.On the other hand,dendritic(5-10 nm)and larger spheroidal(30-40 nm)NiO nanocrystal can be obtained by controlling the precursor and the injection temperature by the "hot-injection" method.It was attributed to the effect of the total surface energy,atomic migration,crystalline surface reaction,and the relative growth rates of different crystal planes for variety of the size and morphology,because those growth thermodynamics and kinetics’ factors were adjusted by changing factors such as precursor,temperature,and synthesis method.2.Li-doped NiO nanocrystals were synthesize by used the“one-pot”method and“hot-injection" method.Through the "one-pot" method,NiO nanocrystals with lithium concentration ranging from 1.20%to 11.04%are obtained.Besides,through the "hot-injection" method,the NiO nanocrystals with a lithium concentration range from 0.23%to 11.03%were obtained.3.Transparent conductive films were prepared by spin-coating from the Li-doped NiO nanocrystals synthesized by the "one-pot" method and"hot-injection" method.By the "one-pot" method,the thickness of the Li-doped NiO film was 24.7 nm,51.3 nm,and 69.8 nm,and the film transmittance was 95.7%,93.3%,and 88.1%respectively.The film conductivity was 6.5*10-2S/cm,which was 390 times larger than undoped ones.On the other hand,the electrical and optical properties of NiO film consisted by NiO nanocrystals synthesized by "hot-injection”method was found that the doping concentration affected the electrical and optical properties.And the film with conductivity of 5 S/cm and transmittance of about 70%was obtained.