Absorption (open squares) and PL (solid triangles) spectra of QDs compared to the PL spectrum of PSF (solid squares). All spectra were recorded for chloroform solutions at room temperature. The inset shows the molecular structure of PSF.
(a) PL spectra of QD:PSF composite films for different wt % of QDs (see inset) in the film. The PL intensity has been corrected for the absorbance at the excitation wavelength . (b) PL excitation spectrum of a QD:PSF film recorded at (solid triangles) together with the absorption spectrum of PSF (open squares) and the PL excitation spectrum of a pure QD film (open circles).
Relative quenching of the donor (PSF) fluorescence as function of the QD concentration in the film. The lines represent Eq. (2) for different Förster distances . The experimental data are obtained for two different batches of QDs, each measured in two sets of experiments.
Time-resolved photoluminescence. (a) PSF emission at of pure PSF (solid squares, QD) and of QD:PSF blends with 20 and QDs. (b) QD emission at of pure QDs and QD:PSF blends 20 and QDs. The red lines represent fits of a biexponential rise to the experimental data. The blue line represents the machine response of the excitation pulse.
(a) Schematic of the QD-LED device structure. The TPBI layer was not used in all devices (see text). (b) Energy levels of the various materials with respect to vacuum.
(a) EL spectra of ITO/PEDOT:PSS/QD:PSF/Ba/Al QD-LEDs for different concentrations of QDs (in wt %) measured at . (b) EL spectrum of an ITO/PDOT:PSS/QD :PSF/TPBI/Ba/Al QD-LED (open triangles). The closed triangles show the corresponding EL spectrum without the TPBI ETL. The solid line represents the PL spectrum of the same film. (c) Current density and luminance of ITO/PEDOT:PSS/QD:PSF/Ba/Al LEDs vs the bias voltage without (solid symbols) and with (open symbols) a TPBI layer.
Relative intensities of QD and PSF emission intensity from photoluminescence (open markers) and electroluminescence (closed markers) vs the concentration of QDs. At high QD wt % the PSF emission becomes very small and the error in the ratio increases.
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