Spectral narrowing of emission in di-substituted polyacetylene

We studied spontaneous and stimulated optical emission in films of di-substituted trans-polyacetylene (t-PA). We found that di-substitution of t-PA drastically changes the polymer optical emission properties, so that photo-generation of exciton and photoluminescence (PL) quantum yields become much higher than those measured in unsubstituted and mono-substituted t-PA. The strong PL is accompanied by high optical gain and emission spectral narrowing at high excitation intensities; the emission spectrum changes from a broad PL band of 100 nm at low intensities to a narrow stimulated emission band of similar to 8 nm at high intensities. These properties show that di-substituted t-PA films can be good candidates for laser medium in the green and blue spectral ranges.