PCPP Derivatives Containing Carbazole Pendant as Hole Transporting Moiety for Efficient Blue Electroluminescence

Abstract

The syntheses and characterization of poly((2,6-(4,4-bis(4-((2-ethylhexyl) oxy)phenyl)-4H-cyclopenta[def]phenanthrene))-co-(2,6-(4,4-bis(4-(((9-carbazolyl)hexyl) oxy)phenyl))-4H-cyclopenta[def]phenanthrene)) (BCzPh-PCPPs) and poly((2,6-(4,4-bis (4-((2-ethylhexyl)oxy)phenyl)-4H-cyclopenta[def]phenanthrene))-co-(2,6-(4-(4-(((9-carbazolyl)hexyl)oxy)phenyl)-4-(4-((2-ethylhexyl)oxy)phenyl)-4H-cyclopenta[def]phenan-threne))) (CzPh-PCPPs), with carbazole unit as pendants, are presented. The carbazole moiety, which can improve the hole injection ability, was introduced as a pendant on the PCPP backbone. The devices of the polymers with the configurations of ITO/PEDOT:PSS/polymers/Ca/Al generate EL emission with maximum peaks at 400450 nm, CIE coordinates of (x = 0.11-0.29, y = 0.11-0.33), low turn-on voltages of 4-6 V, maximum brightness of 60-810 cd/m(2), and luminescence efficiencies of 0.04-0.22 cd/A. The PL spectra of CzPh-PCPPs films did not show any peak at around 550 nm, which corresponds to keto defect or aggregate/excimer formation, even after annealing for 30 h at 150 degrees C in air. Out of the series, CzPh-PCPP1 (PCPP derivative with 10% of carbazole moiety as pendant) shows blue emission with the maximum brightness of 810 cd/m(2) at 9 V, and the highest luminescence efficiency of 0.22 cd/A at 395 mA/cm(2). (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1327-1342, 2009