A compound of the formula wherein: A represents a phenyl group, a naphthyl group, a biphenyl group or two phenyl groups linked by a C 1 -C 8 alkyl chain; B 1 and B 2 in each occurrence are independently selected side chains of the structure -(Y 1) n -L-(Y 2) m -X wherein: Y 1 and Y 2 in each occurrence are independently selected from O, CO 2 - and CH 2 O; m and n in each occurrence are independently selected from 0 or 1; L in each occurrence is a C 2 -C 14 straight chain alkyl group; and X in each occurrence is an independently selected cross linkable group; C is a side chain of the structure -(Z 1) p -M-(Z 2) q -E wherein: Z 1 and Z 2 are independently selected from O, CO 2 - and CH 2 O; p and q in each occurrence are independently selected from 0 or 1; M is a C 1 -C 14 straight chain alkyl group; and E comprises a charge transport group; D is a side chain of the structure -(W 1) r -N-(W 2) s -F wherein: W 1 and W 2 are independently selected from O, CO 2 - and CH 2 O; r and s in each occurrence are independently selected from 0 or 1; N is a C 1 -C 14 straight chain alkyl group; and F comprises a charge transport group or light emitter group; and wherein the charge transport group E does not contain a fluorene group other than those that form part of a spirobifluorenearylamine motif. A represents a phenyl group, a naphthyl group, a biphenyl group or two phenyl groups linked by a C 1 -C 8 alkyl chain; B 1 and B 2 in each occurrence are independently selected side chains of the structure -(Y 1) n -L-(Y 2) m -X wherein: Y 1 and Y 2 in each occurrence are independently selected from O, CO 2 - and CH 2 O; m and n in each occurrence are independently selected from 0 or 1; L in each occurrence is a C 2 -C 14 straight chain alkyl group; and X in each occurrence is an independently selected cross linkable group; Y 1 and Y 2 in each occurrence are independently selected from O, CO 2 - and CH 2 O; m and n in each occurrence are independently selected from 0 or 1; L in each occurrence is a C 2 -C 14 straight chain alkyl group; and X in each occurrence is an independently selected cross linkable group; C is a side chain of the structure -(Z 1) p -M-(Z 2) q -E wherein: Z 1 and Z 2 are independently selected from O, CO 2 - and CH 2 O; p and q in each occurrence are independently selected from 0 or 1; M is a C 1 -C 14 straight chain alkyl group; and E comprises a charge transport group; Z 1 and Z 2 are independently selected from O, CO 2 - and CH 2 O; p and q in each occurrence are independently selected from 0 or 1; M is a C 1 -C 14 straight chain alkyl group; and E comprises a charge transport group; D is a side chain of the structure -(W 1) r -N-(W 2) s -F wherein: W 1 and W 2 are independently selected from O, CO 2 - and CH 2 O; r and s in each occurrence are independently selected from 0 or 1; N is a C 1 -C 14 straight chain alkyl group; and F comprises a charge transport group or light emitter group; W 1 and W 2 are independently selected from O, CO 2 - and CH 2 O; r and s in each occurrence are independently selected from 0 or 1; N is a C 1 -C 14 straight chain alkyl group; and F comprises a charge transport group or light emitter group; and wherein the charge transport group E does not contain a fluorene group other than those that form part of a spirobifluorenearylamine motif.