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We report an ultra-bright, highly efficient, low roll-off, inverted quantum dot-based red light emitting device (QLED) using solution-processed zinc oxide nanoparticles and cesium carbonate films as the electron injection and hole blocking layers, respectively. Record luminance of 165,000 Cd/m 2 has been obtained at a current density of 1000 mA/cm 2 with a low driving voltage of 5.8 V for deep red device with CIE coordinates of (0.69, 0.31).

Low thresholds (∼500 W/cm2) for amplified spontaneous emission (ASE) are reported in films of soluble poly(paraphenylene vinylene)-based conjugated polymer blends. Efficient Förster energy transfer from the absorbing host polymer to the emitting guest polymer is observed. Emission in the blends originates predominantly from the guest polymer. The large spectral shift between the absorption and emission wavelengths lowers the self-absorption losses and results in low ASE thresholds. Initial results show an enhancement in photoluminescence quantum efficiency of the blends.

We report on low threshold photopumped amplified spontaneous emission (ASE) in blends of derivatives of poly (p-phenylene vinylene) and distributed feedback (DFB) lasers fabricated from the same materials. Förster energy transfer is used to spectrally shift the emission away from the absorption band, thereby reducing the optical losses. The concentration of the guest polymer in the blend determines the rate of energy transfer and, thereby, has a strong effect on the observed emission spectrum. The photoluminescence quantum efficiencies (ηPL) of the blends are higher than the ηPL of the pure emissive species (ηPL decreases with increasing amount of the guest polymer in the blends). The blends exhibit optical losses ∼3 cm−1 compared to ∼85 cm−1 in pure host. As a result, the ASE thresholds are reduced from 5000 W/cm2 in the host to 200 W/cm2 in the blends. The corresponding lasing threshold in the DFB structures is 100 W/cm2.

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