Synthesis And The Application In Electrical Bistable Device Of PbS Quantum Dots

With the breakthrough of the synthesis and technology research of inorganic nanomaterials, the semiconductor devices based on the polymer/inorganic nanomaterials composite film have attracted the interests of international researchers. In this thesis, lead sulfide (PbS) quantum dots (QDs) with mean particle size from 3 run to 18 nn were synthesized by the thermal injection method. Meanwhile, the action conditions and key factors determine the particle size and crystalline of PbS QDs. Furthermore, organic-inorganic composite electrical bistable devices have been prepared by utilizing PbS QDs and poly(N-vinylcarbazole) (PVK) film. The main contents are listed as follows:(1) The PbS QDs were prepared using a thermal injection method. Attributing to the processes via fast nucleation at high temperature and slow growth at low temperature, we obtained the PbS QDs with the particle size distributions in the range of 3 nm to 18 nm by controlling the reaction conditions. The particle size, morphology and crystalline structures of PbS QDs were characterized by TEM, HRTEM, XRD, Vis-NIR spectra, and photoluminescence.(2) An organic/inorganic composite electrical bistable device has been fabricated by utilizing composite of PVK and PbS QDs as the active layer. The device exhibits significant electrical bistability and repeatable operation of "read-write-read-erase" is also achieved. Current-voltage characteristics were employed to study the electrical bistability properties of the device by varying the mass ratios of PbS QDs to polymer. The maximum current ratio between the high-conducting state (ON state) and low-conducting state (OFF state) can reach up to 104. The carrier transport mechanisms in the positive voltage region of the ON state and OFF state are described by using different transport models, respectively. The observed conductance switching is attributed to the electric-field-induced charge transfer between the nanocrystals and the polymer, and charge trapping/detrapping in the nanocrystals.