New hyperbranched conjugated polymers containing hexaphenylbenzene and oxadiazole units: convenient synthesis and efficient deep blue emitters for PLEDs application.
In this article, four "A(3)+B(2)+C(2)"-type hyperbranched conjugated polymers (P1-P4) containing hexaphenylbenzene as the core were synthesized successfully for the first time with high yields through one-pot Suzuki polymerization reaction. The copolymerization percent of 1,3,4-oxadiazole units was adjusted to investigate the effect of polymer composition on the physical, optical, and EL properties. All polymers were well-characterized and exhibited good solubility, film-forming ability, and thermal stability. Both the solution and the films of these hyperbranched polymers emitted pure and stable deep-blue light emission, and their PL spectra did not change after annealing at 150 degrees C for 0.5 h in air, indicating that the hyperbranched structure, coupled to the introduced hexaphenylbenzene moieties, effectively suppressed the formation of aggregation excimer and keto defects. Two-layer PLED devices were fabricated to investigate the electroluminescence properties of these hyperbranched polymers, and P3 demonstrated a maximum luminance efficiency of 0.72 cd/A and a maximum brightness of 549 cd/m(2) at 16.5 V.
Li
Zhong'an
Z
Department of Chemistry, Hubei Key Lab on Organic and Polymeric Opto-Electronic Materials, Wuhan University, Wuhan 430072, China.
Ye
Shanghui
S
Liu
Yunqi
Y
Yu
Gu
G
Wu
Wenbo
W
Qin
Jingui
J
Li
Zhen
Z