Abstract
ABSTRACTThree novel poly(2,7‐carbazole)s having hole injection and transporting pendent moieties of carbazole and triphenylamine at the N‐position were synthesized for achieving pure blue electroluminescence. The N‐pendants in the polymers correspond to N‐phenylcarbazol‐2‐yl (P1), N,N‐diphenylamino‐N‐phenylcarabazol‐2‐yl (P2), and 4‐phenyl having a hydrocarbon chain with a triphenylamine terminal (P3), respectively. Electronic, optical, and electroluminescence properties of these polymers were compared with those of a poly(2,7‐carbazole) directly connected with triphenylamine at the N‐position (P0) having an aggregation‐induced emissive property. The photoluminescence (PL) spectra suggested that they could emit in the region of blue light in the film state. Especially, P2 that has the fixed and large diphenylaminocarbazolyl pendant showed a deep‐blue fluorescence with CIE(x, y) = (0.15, 0.07). The P0, P2, and P3 based light emitting diode devices showed maximum electroluminescence wavelengths in the range of 430–450 nm. The P2 device showed pure blue emission (CIE[x, y] = [0.18, 0.16]), high luminance (1130 cd/m2) and current density (628 mA/cm2) at 8 V, whereas low‐energy emissions around 500–600 nm were emerged at higher than 9 V. The P0 and P3 devices also showed a blue electroluminescence in the range of 8–11 V, but their luminance and efficiency were low. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2526–2534
Published Version
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