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1594623 
Journal Article 
Novel green-light-emitting hyperbranched polymers with iridium complex as core and 3,6-carbazole-co-2,6-pyridine unit as branch 
Guan, R; Xu, Y; Ying, Lei; Yang, Wei; Wu, H; Chen, Q; Cao, Y 
2009 
Yes 
Journal of Materials Chemistry
ISSN: 0959-9428
EISSN: 1364-5501 
19 
4 
531-537 
WOS:000262440400013 
Green-light-emitting hyperbranched polymers with iridium
complex as a core and 3,6-carbazole-co2,6- pyridine as a branch were synthesized by Suzuki
polycondensation. The highest occupied molecular orbital (HOMO) and the lowest unoccupied
molecular orbital (LUMO) levels of copolymers reduced gradually with increasing content of 2,6-
pyridine units from 10 to 30 mol%. It was found that as a result of the incorporation of the
pyridine moiety into the polycarbazole backbone, the device efficiencies could be significantly
enhanced. A peak external quantum efficiency (QE), luminous efficiency (LE) and power efficiency
(PE) of 13.3%, 30.1 cd/A and 16.6 1m/W were achieved at 5.6 V, respectively, for the device
derived from PCzPy10Irppy3. Furthermore, a peak luminance of 82059 cd/m(2) was obtained at 14.0
V. The efficiency loss upon the increase of current density was considerably reduced since the
highly branched structures could significantly suppress the interchain interaction between the
facial iridium complexes and the self quenching of Ir complexes due to aggregation. The
hyperbranched framework using the charge transport balanced 3,6-carbazole-co-2,6-pyridine segment
as branch and Ir(ppy)(3) complex as core provided a novel molecular design for highly efficient
phosphorescent green light-emitting polymers.