A type of soluble and thermally stable semiladder polyphenylenes containing carbazole moieties (SLPFCs) have been prepared with a facile and short synthetic route, The full characterizations of structures and properties as well as the performances of electrolumineseence devices of the new polymers are presented. The conjugated backbone of the SLPFCs contained three kinds of constituents: fluorene, ladder-type tetraphenylene, and ladder-type hexaphenylone. The SLPFCs exhibit pure-blue fluorescence (lambda(max) = 445 nm) with high efficiency up to 90% in solution. Electrochemical studies indicate that the introduction of carbazole moieties raises the HOMO energy levels, Furthermore, the single-layer light-emitting devices: using the SLPFCs as the active layer show pure-blue emission (lambda(max) = 447 nm, CIE coordinates: 0.15, 0.05) with maximum luminescence of 5500 cd/m(2) and maximum luminance efficiency of 0.556 cd/A. The attractive properties exhibited by the new semiladder polymers establish them as good candidates for active layers in stable pure-blue light-emitting devices.