Two new poly(phenylene ethynylene)s with alkoxyphenyl substituents were synthesized and characterized. The polymers were amorphous, dissolved readily in common organic solvents, and showed glass-transition temperatures at 162-175 degreesC. They showed blue photoluminescence both in solution and in the solid state due to the steric interaction between the substituents and the main chain that caused an interruption of the conjugation length. The quantum yields in a tetrahydrofuran solution were up to 0.63. Excimer emission was the dominant product of the photoexcitation of thin films of the polymers.