Photoinduced absorption spectral feature as well as their temporal profiles on PPV thin film in femtosecond time regime exhibit a strong pump power density dependence. The increase in pump power density also results in the spectrally narrowed emission (SNE) band superimposed to the well-known photoluminescence from PPV. The dependencies on both pump- and probe densities denote much lower saturation intensity in photoinduced absorption as compared with that in stimulated emission from the identical primary photoexcitations, the singlet excitons. We have also discussed the nature of SNE, which has a correlation with an appearance of ultrafast decay component (τ approx. 1 ps) in temporal decay profile of the photoinduced absorption signal.
|Number of pages||2|
|Publication status||Published - 1999 Jun|
|Event||Proceedings of the 1998 International Conference on Science and Technology of Synthetic Metals (ICSM-98) - Montpellier|
Duration: 1998 Jul 12 → 1998 Jul 18
Bibliographical noteFunding Information:
Finally, it is interesting to see the SNE appeared only at high pump-power density. It should be noted that SNE have strong correlation with the appearance of ultrafast decay time constants (ca. 1 ps) in the temporal profiles of transient absorption signal regardless of the probe wavelength, which is responsible for PA and ground-state bleaching recovery (see the inset (a) and (b) of Fig. l(A) and (B). The absence of any structure due to SE in the transient absorption spectra under this high pump-power density led us to propose that neither an amplification of spontaneous emission nor SE is probable candidates to explain the nature of SNE. We tentatively propose that SNE is likely to result from the radiative recombination from the correlated emitters which produced in photoexcited PPV films under high pump-power density. The further work related on this topic is in progress. This work has been financially supported by Star Project (SCJ) and Creative Research Initiatives (DK) of the Ministry of Science and Technology of Korea.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry