Flexible Quantum Dot Luminescent Materials And Devices

Although quantum dots(QDs)have remarkable potential application in flexible light emitting diodes(LED),the loss of solvent-protected QDs leads to low quantum yield(QY)and poor stability,severely restricting the development.To solve this problem,we proposed the strategy of grafting the QD surface ligands to the polymer matrix.We prepared three QDs of blue(CdS/ZnS)green(CdSe@ZnS/ZnS)red(CdSe/CdS),and mixed with polydimethylsiloxane(PDMS)to obtain flexible photoluminescence device.It was proved by FTIR that hydrosilylation reaction occurred between the organic ligands containing double bonds on the surface of QDs and PDMS.Suitable solvent dosage,purification times of QDs,concentration of QDs in PDMS,and oxidation on the preparation process promoted the dispersivity of QDs in PDMS,quantum yield(QY)of the composites,and the stability of the composites under extreme conditions such as VV bleaching,organic solvents(acetone,ethanol and water),and heating treatment.For CdSe@ZnS/ZnS-PDMS composite,under the optimal preparation conditions,the QY is more than 80%,and the fluorescence intensity unchanged within 60 days out of doors.At last,QD-LED hybrid lighting-emitting devices were further fabricated by molding technique demonstrating satisfied current and thermal stability.Flexible QD-LEDs can be expended to other shapes,such as fibers and blocks,indicating the huge potential of QD-polymer composites for light sources,and displays etc.Biocompatible flexible QD electroluminescent devices can be applied in the field of photodynamic therapy,etc.However,common ITO-PET conductive film has poor flexibility,irresistance of bending,complicated preparation process and high cost.We selected regenerated silk fibroin film with good light transmission,excellent biocompatibility,good flexibility,a variety of processing methods as substrate,and silver nanowire as conductive material,and prepared silk protein-silver nanowire conductive film by a spin coating method.Silver nanowires with a length of 100 ?m and a width of 100 nm were synthesized.The effects of the spin coating rate and the concentration of the silver-ethanol dispersion on the transmittance and conductivity of the conductive films were investigated,silver nanowire film has a light transmittance of 85%and a square resistance of 56 ?/sq under following preparation process:a silver concentration of 0.4 mg/mL,a spin coating rate of 3000 rpm,and a 30 min plasma treatment.The silk fibroin solution was added dropwise to the conductive film,the conductive silver wire was embedded in the silk protein after drying,and a conductive film with transmittance of 70.5%at 550 nm and a square resistance of 65?/sq was obtained.