The invention provides a photopolymerisable or photocrosslinkable reactive mesogen for forming a charge transporting or light emitting polymer network, the mesogen having an asymmetric structure (II): B1-S1-A1-M-(A-S-B)n (II) wherein: A and A1 are chromophores; S and S1 are spacers; B and B1 are endgroups which are susceptible to photopolymerisation or photocrosslinking; M is a non-chromophoric aliphatic, alicyclic or aromatic moiety; and n is an integer from 1 to 3; wherein, when the value of n is greater than 1, each of the groups A, S and B may be the same or different. Preferably, M is of the formula Y−Zm, wherein Y is an aliphatic, alicyclic, aromatic or heterocyclic moiety, Z is an aliphatic linking group and m is an integer from 2 to 4, and wherein each of the Z groups may be the same or different. The invention also provides a material for forming a light emitting or charge transporting polymer network comprising the photopolymerisable or photocrosslinkable reactive mesogen, a charge transporting or light emitting polymer network which is obtained by polymerisation or crosslinking of the mesogen, a process for the preparation of the polymer via photopolymerisation or photocrosslinking of suitable end-groups of the mesogen, a device comprising a polymer layer formed from the charge transporting or light emitting polymer network, a process for applying a charge transporting or light emitting polymer network to a surface and a backlight or display comprising a charge transporting or light emitting polymernetwork.