Synthesis And Optoelectronic Properties Of ?-?-? Copper Indium Sulfide Based On Semiconductor Nanocrystals

Recently,the progresses in the synthesis of nanocrystals have been made from single and binary systems to the heterostructured nanocrystals,and to satisty the fast development in the yield of LED,biomedical applications and solar cells.Among these semiconductor materials,group?-?-?semiconductor nanocrystals,in particular CuInS₂,have been extensively studied because of their excellent optical and electronic properties.The detailed contents are as follows:1.A new phase of zincblende structured CuInS₂ quaternary alloyed semiconductor quantum dots were synthesized by utilizing Cu?Ac?₂,In?Ac?₃ as single source precursor.And,DDT was used to balance the reactivity of the three cationic precursors and prevent phase separation.After the growth of ZnS shells,the highest PL QY can reach as high as 30%.These quantum dots may find various applications,such as LED,biolabeling,solar cells,etc.2.With the highly monodispersed Cu₂S nanocrystals as a novel type of catalyst,Cu₂S-In₂S₃ heterostructured nanocrystals with narrow diameter distribution were constructed by high-temperature precursor injection method.It is also well known that Cu_2-xS is a p-type semiconductor which possesses an x-dependent bandgap energy ranging from 1.2eV for chalcocite to 1.8 eV for digenite and transforms from an indirect-gap semiconductor to a direct one.Whereas,In₂S₃ is an important n-type semiconductor material which has been widely used in solar cells,etc.3.The role of ZnS shell on the photo-physical properties within CuInS₂/ZnS quantum dots?QDs?is carefully studied in optoelectronic devices.Linearly increasing voltage technique?i-CELIV?has been employed to investigate the charge carrier dynamics of both CuInS₂ and CuInS₂/ZnS QDs films.This study shows that charge carriers follow a similar behavior of monomolecular recombination in these film,with their charge transfer rate correlate to the increase of applied voltage.It turns out that the ZnS shell could affect the carrier diffusion process through depressing the trapping states and would build up a potential barrier.4.The temperature-dependence of charge carrier dynamics in the films based on a novel heterostructured Cu₂S-In₂S₃ nanocrystals?NC_S?is investigated using charge carrier extraction by linearly increasing voltage?i-CELIV?technique,meanwhile the CuInS₂ nanorods?NRs?film is used as a reference.The carriers in Cu₂S-In₂S₃ NCs film follows the monomolecular recombination mechanism,which is similar to that in CuInS₂ NRs film.The corresponding diffusion rate would accelerate with the applied voltage,indicating that the Cu₂S-In₂S₃ NCs could potentially promote the movement of carrier and simultaneously affect the monomolecular recombination in comparison with that in CuInS₂ NRs film.This study would be beneficial in the development of nano-devices with NRs films and high performance Cu₂S-In₂S₃ NCs solar cells.