A light emitting device comprising an anode, a cathode, a first light emitting layer between the anode and the cathode, and a second light emitting layer between the anode and the cathode is provided. The first light emitting layer comprises a metal complex represented by formula (1):

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In formula (1), M.sup.1 represents an iridium atom, n.sup.1 represents an integer of 1 or more, n.sup.2 represents an integer of 0 or more, n.sup.1+n.sup.2 is 2 or 3, ring R.sup.1A represents a triazole ring containing a nitrogen atom, E.sup.1, E.sup.11A, E.sup.12A, and a carbon atom, ring R.sup.2 represents an aromatic hydrocarbon ring, E.sup.1, E.sup.2, E.sup.11A, and E.sup.12A each represent a nitrogen atom, R.sup.11A and R.sup.12A represent an aryl group, R.sup.13A represents an aryl group, A.sup.1-G.sup.1-A.sup.2 represents an anionic bidentate ligand, A.sup.1 and A.sup.2 each represent a nitrogen atom, and G.sup.1 represents a single bond.

An organic light-emitting device comprising an anode (101), a cathode (105) and an homogeneous organic light-emitting layer (103) between the anode and the cathode wherein: the light-emitting layer comprises a first light-emitting material mixed with an inert material; the inert material has a HOMO level (HOMO.sub.IM) that is further from vacuum than a HOMO level (HOMO.sub.LEM) of the first light-emitting material and a LUMO level (LUMO.sub.IM) that is closer to vacuum than a LUMO level(LUMO.sub.LEM) of the first light-emitting material; and the inert material comprises up to 25 weight % of the light-emitting layer.

Nanoparticle compositions comprising nanoparticles formed from -conjugated cross-linked polymers are disclosed, together with their methods of manufacture and their applications. Owing to the nature of the cross-links formed therein, the nanoparticle compositions afford a high degree of manufacturing flexibility and control, as well as being amenable to facile purification for the purpose of imaging and electronics applications.