Highly Luminous Sky-Blue Organic Light-Emitting Diodes Based on the Bis[(1,2)(5,6)]indoloanthracene Emissive Layer

An in-depth analysis of the electro-optical and light-emissive properties was carried out with a new fused heteroacene, the bis[(1,2)(5,6)]indoloanthracene. The compound was synthesized in a straightforward bidirectional manner from 1,4-dibromo-2,5-diodobenzene utilizing a reaction cascade of isomerization and cyclization sequences. Bis[(1,2)(5,6)]indoloanthracene exhibits bright luminescence with high quantum yield in solution as well as in the solid state. By using this novel semiconductor as active layer, an efficient organic light-emitting diode (OLED) has been fabricated for which its emission pattern resembles at least two emitters in a single emissive region originated from the same molecule. One has its origin from the single molecule and is similar to the luminescence spectra in solution, whereas the other functions through the formation of aggregates being similar to the emission pattern found with crystals of bis[(1,2)(5,6)]-indoloanthracene. As a result, bright sky-blue OLEDs with very high luminance exceeding 10 000 cd/m(2) were obtained. Such color pattern and performance have not previously been observed with low molecular weight, electron-rich fused polycyclic aromatic compounds and indicate a promising new class of materials for development.