We report on the morphological aspects of thin films prepared from a blue–green light‐emitting conjugated polymer, (methyl‐substituted ladder‐type poly(p‐phenylene, mLPPP)), blended with a solid‐state electrolyte composed either by a crown ether, dicyclohexano‐18‐crown‐6 (DCH18C6), or a high‐molecular‐weight poly(ethylene oxide) (HMWPEO), and a Li salt, lithium trifluoromethanesulfonate (LiCF3SO3, Li triflate (LiTf)), as they have been successfully applied in light‐emitting electrochemical cells (LECs). The surface morphologies of the blend layers were investigated using atomic force microscopy (AFM) in tapping mode, and the ion distribution was probed using X‐ray analysis by means of energy‐dispersive X‐ray spectrometry (EDXS) in the scanning electron microscope (SEM). We show that the two different phase‐separation processes, the complexation tendencies of the ionic species as well as the ionic transport numbers, have tremendous influence on the performances of the corresponding LECs, revealing either rectifying or symmetric optoelectronic characteristics in forward and reverse bias directions. This opens up new possibilities for tuning the optoelectronic properties of ion‐supported organic electronic devices.
For further improvements to the reliability and the white light quality of phosphor‐converted light‐emitting diodes (LEDs), it is imperative to understand how the compositional, optical, and thermal properties of the materials constituting the color‐conversion elements (CCEs) affect their respective thermal loads. By means of a combined optical and thermal simulation procedure, a comprehensive discussion is given on the underlying coherences of the absorption profile of the blue LED light, the phosphor concentration, the quantum efficiency of the phosphor, and the thermal conductivities of the CCEs. Some general strategies of material composition and design are deduced in order to minimize the thermal load of the CCEs, which is a prerequisite for correlated color temperature maintenance and long‐term material reliability of phosphor‐converted white LEDs.
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