Search

Abstract: 3-Cyano-4,6-dimethyl-2-pyridone and 3-cyano-4-methyl-6-phenyl-2-pyridone were synthesized effectively by the reaction of readily available 1,3-diketone and malononitrile directly and in good yield. Upon photoexcitation, 3-cyano-4-methyl-6-phenyl-2-pyridone in ethanol shows strong blue emission. The ground- and excited-state geometries, charge distributions, and excitation energies of 2-pyridone derivatives were evaluated by ab initio calculations. Organic light-emitting diodes (OLED) made using 3-cyano-4-methyl-6-phenyl-2-pyridone as dopant showed blue light emission with a maximum electroluminescence (EL) emission at around 456nm. [Copyright &y& Elsevier]

Exciplex is a well-known charge transfer excited-state complex formed between electron-donor and electron-acceptor molecules. The exciplex studied here is resulted from between the donor mCP and the acceptor PO-T2T, which acts as the host of orange emitting OLEDs. The emitter is orange phosphor Ir(pq)2acac. Our device based on the exciplex host and orange phosphor is very simple, but excellent EL performance was observed. That is, peak current efficiency of 35.3 cd/A, power efficiency of 31.0 lm/W and EQE of 18.7% at a 1.5 wt% orange phosphor, respectively. To date this is the highest orange OLED compared with other orange OLEDs with identical color performance. The better results were ascribed to reasonable device design and contribution from both singlet and triplet of exciplex host as well efficient energy transfer from exciplex host to the orange phosphor. The conclusion is based on the fact that exciplex emission comes from TADF process in which there is small ΔE s-t . This strategy enables to resolve the problem of the lower reverse intersystem crossing (RISC). Besides, warm white OLED was also achieved by lowering the dopant concentration, by which incomplete energy transfer from exciplex host to the orange phosphor could take place. [ABSTRACT FROM AUTHOR]

Abstract: A novel blue-light organic electroluminescence material (OEM) derived from 8-hydroxyquinoline lithium (Liq), bis[(8-hydroxyquinolin)lithium·8-hydroxyquinolin] sodium ([Liq·q−]2·2Na+), was synthesized and investigated. For stereo molecular structure and presence of sodium ions, [Liq·q−]2·2Na+ exhibits higher quantum yield and longer fluorescence lifetime than Liq. When used as light-emitting layer in organic light-emitting diode (OLED), [Liq·q−]2·2Na+ shows the maximum emission peak at 489nm in electroluminescence spectra and emits bluer light with higher current efficiency stability than Liq. Moreover, [Liq·q−]2·2Na+ exhibits excellent thermal stability and film formability. [Copyright &y& Elsevier]