NOVELTY - Composition comprises: a dopant capable of electroluminescence and having an emission maximum of 380-750 nm; a host compound having at least one substituted (1,3,5)triazine unit (I); and a second host compound.    USE - The composition is useful in an organic electronic device, an organic thin-film transistor (claimed), light-emitting diode, light-emitting diode display, light emitting luminaire, diode laser, photodetectors, photoconductive cells, photoresistors, photoswitches, phototransistors, phototubes, photovoltaic device or solar cell.    ADVANTAGE - The composition provides devices with improved efficiency.    DETAILED DESCRIPTION - Composition comprises: a dopant capable of electroluminescence and having an emission maximum of 380-750 nm; a host compound having at least one substituted (1,3,5)triazine unit of formula (I); and a second host compound.    Ar1, Ar2, Ar3 = H, deuterium or aryl.    Provided that at least two of Ar1, Ar2 and Ar3 are aryl and none of Ar1, Ar2 and Ar3 includes an indolocarbazole moiety. INDEPENDENT CLAIMS are also included for:    (1) an organic electronic device comprising a first electrical contact layer, a second electrical contact layer and a photoactive layer between the contact layers, where the photoactive layer comprises the composition; and    (2) an organic thin-film transistor comprising: a substrate; an insulating layer (104); a gate electrode (102); a source electrode (106); a drain electrode (108); and an organic semiconductor layer (110) comprising (I), where the insulating layer, the gate electrode, the semiconductor layer, the source electrode and the drain electrode can be arranged in any sequence provided that the gate electrode and the semiconductor layer both contact the insulating layer, the source electrode and the drain electrode both contact the semiconductor layer and the electrodes are not in contact with each other.    DESCRIPTION OF DRAWING(S) - The Figure illustrates a schematic diagram of an organic field effect transistor showing the relative positions of the electroactive layers of the device in bottom contact mode.    Gate electrode (102)    Insulating layer (104)    Source electrode (106)    Drain electrode (108)    Organic semiconductor layer (110)