Excimer and electromer suppression of tetraphenylsilane-derivative-based blue polymer light-emitting devices (PLEDs) was investigated. Tetraphenylsilane with a rigid bulky structure certainly but not completely suppressed excimer formation among polymer-chain segments. A poor solvent, toluene, resulted in excimer formation in the solid film during the spin-coating process, which could not be suppressed by the incorporation of a bulky moiety onto the polymer backbone. In addition, electromers or electroplexes formed by the strong inter-action between the oxadiazole and diphenyl(4-tolyl)amine groups could not be prevented by the tetraphenylsilane moiety. The influences of the bulky moiety, bipolar unit, and device fabrication conditions on the suppression of excimers or electromers in PLEDs are discussed in detail. (c) 2007 Wiley Periodicals, Inc.