Study Of Surface Photovoltage Characteristics And Synthesis About ZnSe Nanocrystals

In this thesis, a series of ZnSe nanocrystals powder was synthesized respective by theusing of mercapto organic compounds as the modifier agent in aqueous solution. Withusing surface photovoltage as the index and designing the five factors and four levels ofthe orthogonal experiment, established the best plan that Zn concentration was0.05mol/L,nZn:nSe:nTGA=1:0.5:1.5, pH=11, temperature was90℃, reflux time is3h as preparing ZnSenanocrystals. The effects of test factors from primary to secondary order was: Znconcentration, reflux time, temperature, nZn:nSe:nligand, pH. And discussed the effect ofdifferent reflux time on the size and optical properties of ZnSe nanocrystalline grains withreaction time as a single variable. Then a series of ZnSe nanocrystals was synthesizedrespective by the using of TGA, TG, MPA and L-Cys as the modifier agent in aqueoussolution, by testing of different ligand effects on ZnSe nanocrystalline structurecomposition and optical property of the situation.By X-ray diffraction of ZnSe quantum dots prepared under optimum conditions thephase retrieval and particle size calculations, and the results showed that the ZnSenanocrystalline cubic zinc blende structure, a diffraction peak (220) plane of the ZnS largeangular offset, indicating ZnS along ZnSe (220) crystal face coated, Jade software tocalculate an average particle size of the sample is about2.5nm; By transmission electronmicroscopy, microscopic appearance of HRTEM and electron diffraction pattern analysisof the sample, sample preparation was found to be approximately spherical, with a clearlattice fringes, is a multi-crystalline phase, consistent with the results of X-ray diffraction;Fourier transform infrared spectroscopy (FT-IR) and Raman spectra (Raman) analyzed thecomponent and bonding conditions of the sample, the results indicated that the ligand inthe sample prepared for the core-shell-type ZnSe/ZnS/ligand structure; Using surfacephotovoltage spectroscopy, field-effect surface photovoltage spectroscopy andfluorescence spectroscopy to analyze TGA, TG, MPA and L-Cys four kinds of ligandmodification electronic transition behavior of ZnSe surface samples, and found that thesurface of the sample expressed as N-type photovoltaic properties; Also analyzed the different reflux time of ZnSe nanocrystals prepared from X-ray diffraction patterns andUV-Vis absorption spectra, the results show with increasing refluxing time, the averageparticle size increases, the UV absorption peak red shift.The band structure, partial density of states and optical properties were calculatedabout the (110) plane of the ZnSe crystal with doped S ratio was25%,50%,75%,100%by CASTEP module of Materials Studio software. Analysis the electron orbital structure,surface bonding and spectral absorption of the (110) plane of the ZnSe crystal with dopedS.