A nondoped device based on the PIAnTAZ emitter shows blue electroluminescence with a maximum EQE of 7.96%, a maximum luminance of 58 675 cd m−2 and negligible efficiency roll-offs.
Organic light-emitting diodes (OLEDs) have been greatly developed in recent years owing to their abundant advantages for full-color displays and general-purposel ightings. Blue emitters not only provide one of the primary colors of the RGB (red, green and blue) display system to reduce the powerc onsumption of OLEDs, but are able able to generate light of all colors, includingb lue, green, red, and white by energy transfer processes in devices. However,i t remains ac hallenge to achieve high-performance blue electroluminescence, especially for nondoped devices.I nt his paper,w ereportablue light emitting molecule, DPAC-AnPCN, which consists of 9,9-diphenyl-9,10-dihydroacridine and p-benzonitrile substituted anthracenem oieties. The asymmetrically decoration on anthracene with different groups on its 9a nd 10 positions combines the merits of the respective constructingu nits and endows DPAC-AnPCN with pure blue emission, high solid-statee fficiency,g ood thermal stabilitya nd appropriate HOMO and LUMO energy levels. Furthermore, DPAC-AnPCN can be appliedi nanondoped device to effectively reduce the fabrication complexity and cost. The nondoped device exhibits pure blue electroluminescence( EL) locating at 464 nm with CIE coordinates of (0.15, 0.15). Moreover, it maintains high efficiency at relatively high luminescence. The maximum externalq uantum efficiency (EQE) reaches 6.04 %a nd still remains 5.31% at the luminanceo f1 000 cd m À2 showing av ery small efficiency roll-off.
Chaos in nonlinear dynamical systems is featured with irregular appearance and with high sensitivity to initial conditions. Near-infrared light chaos based on semiconductor lasers has been extensively studied and has enabled various applications. Here, we report a fully-developed hyperchaos in the mid-infrared regime, which is produced from interband cascade lasers subject to the external optical feedback. Lyapunov spectrum analysis demonstrates that the chaos exhibits three positive Lyapunov exponents. Particularly, the chaotic signal covers a broad frequency range up to the GHz level, which is two to three orders of magnitude broader than existed mid-infrared chaos solutions. The interband cascade lasers produce either periodic oscillations or low-frequency fluctuations before bifurcating to hyperchaos. This hyperchaos source is valuable for developing long-reach secure optical communication links and remote chaotic Lidar systems, taking advantage of the high-transmission windows of the atmosphere in the mid-infrared regime.
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