Synthesis Technology And Optical Properties Of Low Dimensional PbS Nanocrystals By Hydro-and Solvothermal Methods

Lead sulfide(PbS)is an important semiconductor material,which has been widely concerned in solar cells and infrared detectors owing to its unique photoelectric properties.Among the synthesis methods of PbS,hydro-and solvothermal methods have many advantages,such as green environmental protection and low cost.In this paper,PbS nanocrystals(NCs)with various morphologies were synthesized by hydro-and solvothermal methods,and the morphology evolution mechanism and optical properties of the products were characterized and analyzed.Additionally,PbS thin films were synthesized by one-step hydro-and solvothermal methods,and the effect of reaction conditions on the morphologies of the thin films were characterized.The effect of PbS thin films on the photoelectric properties of PbS based perovskite solar cells(PSCs)was also studied by FDTD(finite-difference-time-domain)method.The main conclusions of this paper were as follows:(1)In hydrothermal method,hexapod/octapod dendritic and face center concave cube PbS NCs were synthesized.The results showed that the morphology of the products was affected by the change of precursor molar ratios,reaction time,reaction temperature and L-cysteine contents.Moreover,the light absorption of the PbS NCs were influenced by their multiple morphologies.(2)In solvothermal method,various morphologies of PbS NCs were synthesized in ethylenediamine(en),such as "magic cubes",and octagonal dendrites.With the increasing of reaction temperature,the morphologies of PbS NCs in deionized water and en showed almost contrary evolution process:in deionized water,the products changed from dendrites to face center concave cubes;while in en,the initial morphology were cubes,and finally evolved into octagonal shape.Therefore,it is found that the chelation of en to Pb2+is the main reason for the evolution mechanism of product morphologies.(3)PbS thin films were synthesized on alumina(Al2O3)ceramics by hydro-and solvothermal methods.The change of reaction conditions were the important factors affecting the film morphology.Octagonal structures were obtained in deionized water,cubic structures were obtained when eg(ethylene glycol)and en were used as solvent.(4)The effect of PbS thin films on the photoelectric performance of perovskite solar cells with the surface morphology of dendrites,cubes and face center concave cubes were studied by simulation(FDTD),the results showed that the light absorption performance of solar cell units changed obviously.