Abstract: A polymer comprising units ?, ?, ? and ? wherein: unit ? is present at 30 mole % to 60 mole % and is an optionally substituted arylene; unit ? is present at 1 mole % to 30 mole % and is a unit comprising an optionally substituted fluorene; unit ? is present at 1 mole % to 40 mole % and comprises aryl substituted nitrogen, or an optionally substituted triazine; unit ? is present at 0.5 mole % to 15 mole % and comprises an iridium complex; and optionally up to 20 mole % of other units if the total of ?, ?, ? and ? is less than 100 mole %.

Abstract: Composition having an organic semiconducting material and a triplet-accepting material of formula (I) with a triplet energy level lower than the triplet energy level of the organic semiconducting material, in which each Ar is optionally substituted aryl or heteroaryl group, n is 1-3, m is 1-5, q is 0 or 1, each R3 is H or a substituent, and each R4 is H or a substituent. Where R4 is not H, R4 and (Ar)m bound to the same carbon atom may be linked by a direct bond or a divalent group. Where n or m is at least 2, adjacent Ar groups may be linked by a divalent group. Where q=0, R3 is not H and is linked to (Ar)n by a direct bond or a divalent group.

Abstract: A polymer comprising units ?, ?, ? and ? wherein: unit ? is present at 30 mole % to 60 mole % and is an optionally substituted arylene; unit ? is present at 1 mole % to 30 mole % and is a unit comprising an optionally substituted fluorene; unit ? is present at 1 mole % to 40 mole % and comprises aryl substituted nitrogen, or an optionally substituted triazine; unit ? is present at 0.5 mole % to 15 mole % and comprises an iridium complex; and optionally up to 20 mole % of other units if the total of ?, ?, ? and ? is less than 100 mole %.

Abstract: Composition having an organic semiconducting material and a triplet-accepting material of formula (I) with a triplet energy level lower than the triplet energy level of the organic semiconducting material, in which each Ar is optionally substituted aryl or heteroaryl group, n is 1-3, m is 1-5, q is 0 or 1, each R3 is H or a substituent, and each R4 is H or a substituent. Where R4 is not H, R4 and (Ar)m bound to the same carbon atom may be linked by a direct bond or a divalent group. Where n or m is at least 2, adjacent Ar groups may be linked by a divalent group. Where q=0, R3 is not H and is linked to (Ar)n by a direct bond or a divalent group.

Abstract: A light-emissive polymer comprising the following unit: where X is one of S, O, P and N; Z is N or P; and R is an alkyl wherein one or more non-adjacent C atoms other that the C atom adjacent to Z may be replaced with O, S, N, C?O and —COO— or an optionally substituted aryl or heteroaryl group.