Electroluminescence (EL) and photoluminescence (PL) have been studied in po
lyacetylene derivatives with various substituents. Intense green and blue E
Ls are observed in poly(diphenylacetylene)s and in poly(1-alkyl-2-phenylace
tylene)s, respectively. While, red PL and EL in mono-substituted polyacetyl
ene derivatives are much weaker. Detailed dependence of EL and PL on molecu
lar structure of substituents have been discussed. Spectral narrowing of PL
and lasing have also been realized with intense excitation.