Visible red random lasing centered at ∼611 nm has been observed in Y2O3:Eu3+/ZnO films at room temperature. Using a 355 nm laser source to excite the ZnO films, ultraviolet (UV) random lasing has been observed. The UV lasing spectrum can be tuned to overlap strongly with the F70-L56 excitation spectrum of Eu3+ ions centered at ∼394 nm by controlling the pump power, leading to very efficient radiative energy transfer from the ZnO films to Eu3+ ions. As a result, a red random lasing centered at ∼611 nm corresponding to the D50-F72 transition of Eu3+ ions was observed.

We report a bright cadmium-free, InP-based quantum dot light-emitting diode (QD-LED) with efficient green emission. A maximum brightness close to 700 cd/m2 together with a relatively low turn-on voltage of 4.5 V has been achieved. With the design of a loosely packed QD layer resulting in the direct contact of poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl) benzidine] (poly-TPD) and 2,2′,2″-(1,3,5-benzinetriyl)-tris(1- phenyl-1-H-benzimidazole) (TPBi) in the device, a ternary complementary white QD-LED consisting of blue component (poly-TPD), green component (QDs), and red component (exciplex formed at the interface between poly-TPD and TPBi) has been demonstrated. The resulting white QD-LED shows an excellent color rendering index of 95. © 2012 American Institute of Physics

Large improvement in random lasing action at ultraviolet wavelength has been achieved from highly disordered ZnO films with Ag coating. The lasing threshold can be reduced by two times and slope efficiency can be increased by 5.5 times. The improvement is due to the presence of Ag coating, which enhances the surface coupling of lasing emission from the ZnO films by surface-plasmon resonance and reduces the scattering loss experienced by the random cavity modes. Furthermore, the enhancement of lasing efficiency is dependent on the Ag coating’s surface roughness, which can be controlled through the surface morphology of ZnO films.

We report a hybrid, quantum dot (QD)-based, organic light-emitting diode architecture using a noninverted structure with the QDs sandwiched between hole transporting layers (HTLs) outperforming the reference device structure implemented in conventional noninverted architecture by over five folds and suppressing the blue emission that is otherwise observed in the conventional structure because of the excess electrons leaking towards the HTL. It is predicted in the new device structure that 97.44% of the exciton formation takes place in the QD layer, while 2.56% of the excitons form in the HTL. It is found that the enhancement in the external quantum efficiency is mainly due to the stronger confinement of exciton formation to the QDs.

Articles you may be interested inHigh-temperature lasing characteristics of randomly assembled ZnO nanowires with a ridge waveguideWe report the high-temperature ultraviolet random laser action in ZnO nanoneedles. The characteristic temperature of the ZnO nanoneedle lasers was derived to be 138 K in the temperature range from 300 to 615 K. The cavity length of the random lasers as a function of temperature was determined by Fourier transform spectroscopy. The cavity length decreased with an increase in temperature from ϳ14 m at 300 K to ϳ 2 m at 550 K. The optical gain of the ZnO nanoneedle lasers at high temperature is attributed to a self-compensation mechanism in the cavity length.