We designed and synthesized a three-branched isophorone-based compound, 4,4',4"-tri[2-(3-dicyanomethylene-5,5-dimethylcyclohex-1-enyl)vinyl]trip henylamine, as well as its one- and two-branched analogues. Their photophysical, electrochemical and electroluminescent characters showed a regular change with increasing branches. Density functional theory was employed to study their electron density distribution. Using the dyes as light-emitting layers without doping, organic light-emitting diodes showed appropriate red emission at lambda(max) = 647-670 nm and a maximum brightness of 1801 cd m(-2). Moreover, the results shows that the device using the single-branched material as a pure emitting layer has higher efficiency and lower turn-on voltage than using multi-branched materials. (c) 2006 Elsevier B.V. All rights reserved.