Hot-injection Synthesis Of Lead Selenide Colloidal Quantum Dots

IV-VI group compound colloid quantum dots (CQDs) is a series of novellow-dimension semiconductor materials. They possess remarkable quantum size effect,surface effects and multiple exciton generation so that they can be used to fabricate solarcells, NIR photodetectors, biomedical imaging and fiber communications. Then the solutionprocess is simple and effective with low environment condition requirement, substrate free.It helps to produce large-area quantum dots devices in convenient, convenience way.Bulk lead selenide crystals take a forbidden bandwidth of0.28eV and its exciton Bohrradius is46nm. Thus the absorbance peak of the NCs can be modulated by controlling PbSeNCs size in larger spectra area for quantum size effect. In this thesis, we utilize hot-injectionprocess to produce PbSe CQDs and analyze their characterizations. Then we do advancedresearch on PbSe CQDs thin films and provide experience parameters.To synthesis PbSe CQDs, we dissolved Se powder in Tri-n-octylphosphine (TOP) andheat up in Schlenk line to produce Se precursor. Then we mixed phenyl ether (oroctadecylene), oleic acid, lead actetate (lead oxide) and/or TOP to synthesize lead precursor.Then TOPSe precursor was injected into180lead precursor for PbSe growth.As-synthesized quantum dots were passivated by oleic ligands and stable dispersed inorganic solvent. Through mass experiments, we obtain different shaped stable PbSe CQDswith size distribute in the arrange of10nm~30nm, and they all gain Rock-salt structure,absolute blue shift of absorption peaks and strong symmetrical fluorescence peaks. In thesis,we focus on recipe to synthesize monodispersed CQDs, stability, self-assemble structure,growth mechanism and effect of TOP in lead precursor, conclude experience parameters andnotice of experiment to direct PbSe synthesis in high efficiency.In this project, we still study the process of fabricate PbSe CQDs thin films as utilizedspin coating and dip coating. The experience parameter: in spin coating, the concentration ofPbSe CQDs in organic solvent is50~100mg/mL, compared to5~20mg/mL of dip coating;in general, spin coating at least20times can achieve good performance thin films, and to dipcoating with speed of10cm/min, this number is at least15times.