TECHNOLOGY FOCUS - POLYMERS - Preparation (disclosed): No general method for the preparation of the polymer (P1) is given. WIDER DISCLOSURE - Also disclosed is an iridium complex containing a (pentaphenyl)phenyl ligand of formula (III), as new.    G'=primary ligand;    R'1 and R'2=auxiliary ligands.    EXAMPLE - A polymer (P1a) derived from 9-((pentaphenyl)phenyl)carbazole was prepared by Horner-Wadsworth-Emmons reaction (HWE reaction) as follows. Under alkaline conditions, of LiCl and potassium tert-butoxide (tert-BuOK) in dimethylformamide (DMF) and tetrahydrofuran (THF); 9-(2',3',4',5',6'-pentaphenyl-biphenyl-4-yl)-9H-carbazole-3,6-dicarbaldehyde (a) and (4-(diethoxy-phosphorylmethyl)-2-(2-ethyl-hexyloxy)-5-methoxy-benzyl)-phosphonic acid diethyl ester (b), were reacted for 30 hours, where the compounds reacted to form carbon-carbon double bond and polymerized; followed by reacting 9-(2',3',4',5',6'-pentaphenyl-biphenyl-4-yl)-9H-carbazole-3-carbaldehyde (c) for 24 hours, 90%, to obtain the polymer (P1a) of formula (Ia) (where n = not defined). The polymer (P1a) had number average molecular weight (Mn) of 24000, weight average molecular weight (Mw) of 35500, and polydispersity index (PDI) of 1.48. A comparative polymer (P2) was a polymer of formula (Ib) (where n' = not defined) having Mn of 6900, Mw of 9100, and PDI of 1.32. The effect of the thermal stability of the test/comparative polymer on the performance of device comprising the polymer was then evaluated as follows. The first part related to the stability of the fabricating process at the early stage. The film of the polymer material (P1a)/(P2) was formed by spin coating without the requirement of vacuum evaporation, such as for the small molecule material, but the electrode was formed by thermal evaporation of metal. Thus, although the film of the compound was not heated directly, the temperature was still high as the metal was deposited on the polymer film. Hence, if the thermal decomposition temperature was too low, decomposition could occur during evaporation. The second part related to the stability of the fabricating process at the later stage. An external voltage was continuously applied on the device during operation to generate heat and besides the heat of the operating environment was absorbed by the polymer in the device. Thus, if the glass transition temperature (Tg) was low, the organic material could soften and the efficiency of the device could be affected. Before fabricating the device, thermogravimetry analysis (TGA) was used to measure the thermal decomposition temperature (Td) of the compound, and differential scanning calorimetry (DSC) was used to measure the Tg of the compound so as to realize the thermal property of the material. The results for the test/comparative polymers were as follows: Tg = 432/440, and Td = 112/83. Thus for the test polymer, the Td was higher than 400 degrees C i.e. it showed good thermal stability; and the Tg was between 100-120 degrees C i.e. higher than the comparative polymer without (pentaphenyl)phenyl group on the backbone. It indicated that the steric effect of (pentaphenyl)phenyl group was so large that the rotational degree of freedom was decreased and thus Tg was increased.