Light-emitting composition

A composition comprising a light-emitting compound having a peak wavelength of at least 650 nm and a material comprising a group of formula (I):

• wherein Ar1, Ar2 and Ar3 in each occurrence are independently selected from a C6-20 aromatic group and a 6-20 membered heteroaromatic group of C and N ring atoms, and at least one of Ar1, Ar2 and Ar3 is a 6-20 membered heteroaromatic group of C and N ring atoms;
• x, y and z are each independently at least 1;
• n, m and p are each independently 0 or a positive integer;
• R1, R2 and R3 in each occurrence is independently a substituent or a single bond to a polymer chain, wherein the group of formula (I) has no more than 3 single bonds to a polymer chain;
• and
• R1, R2 and R3, if present, independently in each occurrence is selected from the group consisting of F;
• CN;
• NO2;
• and C1-20 alkyl wherein one or more non-adjacent, non-terminal C atoms of the alkyl group may be replaced with O, S, NR2, SiR22, COO or CO wherein R2 in each occurrence is a C1-20 hydrocarbyl group.