Charge‐Transporting Polymers based on Phenylbenzoimidazole Moieties

Abstract

A series of novel styrene functionalized monomers with phenylbenzo[d]imidazole units and the corresponding homopolymers are prepared. These side‐chain polymers show high glass‐transition temperatures that even exceed the corresponding value for the common electron‐transporting material 1,3,5‐tris(1‐phenyl‐1H‐benzo[d]imidazol‐2‐yl)benzene (TPBI). Similar electronic behavior between the polymers and TPBI is shown. The polymers are used as matrices for phosphorescent dopants. The fabricated devices exhibit current efficiencies up to 38.5 cd A−1 at 100 cd m−2 and maximum luminances of 7400 cd m−2 at 10 V with a minimum turn‐on voltage as low as 2.70 V in single‐layer devices with an ITO/PEDOT:PSS anode (ITO = indium tin oxide, PEDOT:PSS = poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonate)) and a CsF/Ca/Ag cathode.

New polymer matrix system for phosphorescent organic light‐emitting diodes and the role of the small molecular co‐host

“…Recently, we presented a series of polymer matrices for phosphorescent dopants using a polystyrene‐like backbone carrying hole and electron transporting side groups. These new materials led to efficient PLEDs with low onset voltage 10–12. We also presented a new ambipolar matrix for phosphorescent PLEDs 13.…”

Silicon-based electron-transport materials with high thermal stability and triplet energy for efficient phosphorescent OLEDs

“…Initially, 2-(4-bromophenyl)-1-phenyl-1H-benzo[d]imidazole was prepared in quantitative yield from 4-bromobenzaldehyde and N-phenylbenzene-1,2-diamine as the starting materials [17]. Compounds 1e4, which were the final products, were synthesized by conducting a direct substitution reaction between (4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl)lithium and Me n SiCl m (n ¼ 0, 1, 2, 3, and m ¼ 4Àn) according to the protocol in the literature [16].…”

“…n-BuLi (2.5 M solution in nhexane), trimethylchlorosilane, dimethyldichlorosilane, trichloromethylsilane, and tetrachlorosilane were purchased from Aldrich and used in this experiment without further purification. 2-(4-bromophenyl)-1-phenyl-1H-benzo[d] imidazole was synthesized according to the protocol mentioned in literature [17].…”

New Class of Wide Energy Gap Benzotriimidazole Optical Materials

“…One commonly-reported strategy to improve the yield for the synthesis of benzimidazoles is a two-step condensation reaction [26]. This strategy was adapted to the benzotriimidazole synthesis to improve the overall yield, as well as to improve the ratio of the product mixture in favor of the desired triple-condensed product.…”