We report measurements of photoluminescence from films of a soluble phenylenevinylene polymer that has prospective importance as the emissive material in light-emitting diodes. We show unambiguously that there is long-lived emission in this material due to excimers and estimate that the quantum yield for excimer formation is as high as 50%. Since excimers in this polymer largely decay nonradiatively at ambient temperature, their prominence serves to drastically reduce the possible efficiency of electroluminescent conjugated polymer devices.

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Stimulated emission is demonstrated by optically pumping chromophores within the liquid‐crystal domains of 1D bandgap structures that are derived from holographic polymer‐dispersed liquid‐crystal (H‐PDLC) gratings (see Figure). Electrically switchable laser resonance is also possible using the H‐PDLC, since applying an electric field across the grating aligns the directors of the liquid crystal, diminishing the refractive index profile and, consequently, the lasing action.

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