Tesi di dottorato di ricerca
Dynamics of Strongly Coupled Organic Microcavities
Settore scientifico disciplinare
Corso di studi
Relatore Prof. La Rocca, Giuseppe
- optical microcavities
- thin films
Data inizio appello
Data di rilascio
In this thesis we have studied the physics of strongly coupled J-aggregate microcav-<br>ities.<br><br>We addressed the problem of disorder in organic microcavities,<br>previously approached only with a classical macroscopic method. <br>We numerically<br>analyzed the effect of disorder at a microscopic level, characterizing the polariton localization properties. <br>The localization at the bottom of lower polariton branch has been<br>studied in detail, for its importance in view of the polariton condensation.<br>We also addressed the timescales on which the localization is expected to be of experimental relevance, calculating the time evolution of a polariton wavepacket.<br><br>A second issue of this thesis is the construction of a model for the optical dynamics<br>of J-aggregate microcavities.<br>We build our model from a<br>microscopic approach: first describing the optically active material, the J-aggregate<br>film, following a well-known and successful approach, and then generalizing the model<br>for the bare film to the microcavity case.<br>We simulated the bare film absorption and<br>emission spectra, fitting our parameter to recover their FWHM behavior with the<br>temperature.<br>We calculated the polariton relaxation dynamics following the scattering with molecular vibrations, we built a rate equation, solved it and the angle-resolved photoluminescence.<br>Our model explains the thermal activation of the<br>upper polariton photoluminescence and its dependence on the Rabi splitting value, demonstrating the occurrence of a relaxation bottleneck inside the, so-called, exciton reservoir.
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