A new series of full hydrocarbons, namely 4,4'-(9,9'-(1,3-phenylene) bis(9H-fluorene-9,9-diyl))bis(N,N-diphenylaniline) (DTPAFB), N,N'-(4,4'-(9,9'-(1,3-phenylene)bis(9H-fluorene-9,9-diyl))bis(4,1-phenyl ene))bis(N-phenylnaphthalen-1-amine) (DNPAFB), 1,3-bis(9-(4-(9H-carbazol-9-yl) phenyl)-9H-fluoren-9-yl)benzene, and 1,3-bis(9-(4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)-9H-fluoren-9-yl )benzene, featuring a highly twisted tetrahedral conformation, are designed and synthesized. Organic light-emitting diodes (OLEDs) comprising DNPAFB and DTPAFB as hole transporting layers and tris(quinolin-8-yloxy)aluminum as an emitter are made either by vacuum deposition or by solution processing, and show much higher maximum efficiencies than the commonly used N,N'-di(naphthalen-1-yl)-N,N'-diphenylbiphenyl-4,4'-diamine device (3.6 cd A(-1)) of 7.0 cd A(-1) and 6.9 cd A(-1), respectively. In addition, the solution processed blue phosphorescent OLEDs employing the synthesized materials as hosts and iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N, C-2] picolinate (Flrpic) phosphor as an emitter present exciting results. For example, the DTPAFB device exhibits a brightness of 47 902 cd m(-2), a maximum luminescent efficiency of 24.3 cd A(-1), and a power efficiency of 13.0 lm W-1. These results show that the devices are among the best solution processable blue phosphorescent OLEDs based on small molecules. Moreover, a new approach to constructing solution processable small molecules is proposed based on rigid and bulky fluorene and carbazole moieties combined in a highly twisted configuration, resulting in excellent solubility as well as chemical miscibility, without the need to introduce any solubilizing group such as an alkyl or alkoxy chain.