Efficient Deep-Blue Electroluminescence from an Ambipolar Fluorescent Emitter in a Single-Active-Layer Device

Abstract

A new ambipolar molecule based on a carbazole−fluorene−oxadiazole triad is reported. In a single-active-layer device, the compound reveals a deep-blue electroluminescence with CIE coordinates of (0, 157, 0.079). An external quantum efficiency of 4.7% is achieved if the ambipolar material is formed into a thin layer by thermal evaporation.

Effective management of intramolecular charge transfer to obtain from blue to violet-blue OLEDs based on a couple of phenanthrene isomers

“…[9] Thus, it will lead to many functional groups with high fluorescent yields which cannot be introduced owing to their large π conjugation, such as anthracene, [10] fluorene, [11] styrylarylene [12] and pyrene [13] derivatives and so forth. Furthermore, the weak D-π-A type emitters will either decrease the fluorescent quantum yield and charge-transporting ability, [14] or to some extent increase the synthetic difficulty when large molecular weight and/or bulky structure are usually required for good thermal and morphological stability.…”

Switching and memory characteristics of thin films of an ambipolar organic compound: effects of device processing and electrode materials

“…The organic compound used in this study was 2-(4-(7-(9H-carbazol-9-yl)-9,9-dihexyl-9H-fluoren-2-yl)phenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole; the material was synthesized as described previously and has been used in the fabrication of organic light-emitting devices [21]. This compound is an ambipolar molecule, incorporating both electron transporting (oxadiazole) and hole transporting (carbazole) chemical groups.…”

“…Other variations in the memory device processing conditions were also explored, including evaporating (instead of spin-coating) the ambipolar organic compound [21] or treating the bottom Al electrode with an oxygen plasma prior to coating with the organic film. The results of these studies remain inconclusive.…”

New limb-structured blue light-emitting material comprising an anthracene core with bulky substituents at its 2, 3, 9, and 10-positions

“…To date, many fluorescent blue emitters have been reported, such as the derivatives of anthracene [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], phenylene [19,23,24], pyrene [25][26][27][28], fluorene [29][30][31][32][33][34], carbazole [35][36][37][38], triarylamine [21,41,42] as well as other aromatic hydrocarbons [39,40]. In spite of this, there is still a clear need for further improvement in terms of efficiency and color purity compared to red and green emitters.…”