A composition comprising a light-emitting material having a photoluminescent spectrum with a peak wavelength of more than 600 nm and material comprising a group of formula (I): wherein 1 2 3 4 Ar1, Ar2, Ar3 and Ar4 are each independently a C6-20 aryl group which is unsubstituted or substituted with one or more substituents, Ar5 independently in each occurrence is a heteroarylene group or a C6-20 arylene group which is unsubstituted or substituted with one or more substituents, and m is 0, 1, 2 or 3. The composition may be used in an organic light-emitting device.