Blue light-emitting organic electroluminescent devices

Abstract

Organic electroluminescent (EL) devices with multilayered thin-film structures which emitted bright blue light were constructed. Two empirical guides for the selection of blue-emitting materials were established. The keys to obtain the EL cells with high EL efficiency were excellent film-forming capability of an emitter layer and the appropriate combinations of emitter and carrier transport materials for avoiding the formation of exciplexes. In one of our organic electroluminescent devices, blue emission with a luminance of 700 cd/m 2 was achieved at a current density of 100 mA/cm 2 and a dc drive voltage of 10 V.

Improved electron injection in polymer light-emitting diodes using anionic conjugated polyelectrolyte

“…͓DOI: 10.1063/1.2989133͔ Electroluminescent ͑EL͒ devices based on conjugated polymers continue to be of interest as potential elements for flexible displays. [1][2][3][4] Although encouraging progress has been made in recent years, injection from the electrodes into the luminescent conjugated polymers continues to be a problem. The mismatch between the work function of the metallic electrode ͑cathode͒ and the lowest occupied molecular orbital energy level of the semiconducting polymer controls charge injection into the devices, thereby limiting the device efficiency.…”

Some Features of Liquid Crystalline Oxadiazoles

“…In 1990, it was found that a compound with 1,3,4-oxadiazole is an excellent electron transport material in an organic electroluminescent diode [21]. After this report, the research to use various oxadiazole molecules to obtain high electroluminescence performances strongly increased.…”

Non-doped, blue-emitting, color-stable, organic light-emitting diode based on 2,2′:6′,2″-ternaphthalene

“…Since the first reports of organic electroluminescent (EL) devices in the late 1980s [1][2][3][4], there has been significant interest in the field of organic light-emitting diodes (OLEDs) driven by questions related to fundamental research as well as by proposed industrial applications. An example is solid-state lightning [5][6][7], which holds great promise as an energy-efficient light source.…”

“…Another problem related to the issue of a high band gap is the consequence that the lowest unoccupied molecular orbital (LUMO) is close to the vacuum energy level, which reduces the lifetimes of blue OLEDs because the material is susceptible to oxidation. Nevertheless, there are many reports on blue-emitting OLEDs [4,[11][12][13][14][15][16][17][18][19][20] and the optimization of device structure as well as the investigation of new blue emitters is still in progress.…”