Emission Properties of Polydioctylfluorene and InP/ZnS Quantum Dots Nanocomposites Devices

Two red emitters InP/ZnS quantum dots (QDs) (absorption 570 nm/emission 605 nm and absorption 597/emission 624) were inserted at different concentrations in the blue emitting polymer poly(9,9'-dioctylfluorene) (PFO). Nanocomposites were obtained by mixing the QDs as purchased and the polymer dissolved in the appropriate solvent and deposited by spin coating to give homogeneous films. The morphological properties were characterized by scanning electron microscopy (SEM), that showed a good level of dispersion of the QDs within the polymer. The study of the optical and electrooptical properties of the nanocomposites layer inserted in OLED devices (glass/ITO/PEDOT:PSS/PFO-QD/Ca/Al) is reported and compared to pure polymer based device. Photoluminescence and electroluminescence spectra show an energy transfer from the polymer to QDs in presence of the nanocomposites containing InP/ZnS quantum dots that absorb at 570 nm.