Migrating exciton

The impurities may capture this migrating exciton and lose its excess energy. The mutual annihilation of two or more triplet excitons occurs in the same polymer chain and delayed fluorescence is observed. 

To summarize, absorption of a photon by a conjugated polymer creates an exciton that can then sample many potential binding sites within its lifetime. Emission from the excited state is observed only if there is no bound analyte encountered by the migrating exciton. If the analyte is encountered there is quenching of the emission, and it is this amplified dimunition in emission intensity that serves as an indication (signal transduction) that the analyte is present. 

External Field. Examples are the interaction of a molecule in a solid with a phonon field83,156 or a migrating exciton.88,129,167 Both spin-free and point-group selection rules may turn out to be of some importance. (Radiative transitions are often treated in this formalism.)... 

The lifetime of migrating exciton is 10 see. During that time the exciton may "visit" several molecules over a long... 

The nature of the light emissions is influenced by the way in which the absorbed energy is transferred through the polymer matrix. In crystalline polymers, exciton migration is possible as all molecules lose their energetic individuality and all electronic and oscillation levels are coupled [20]. Thus, new exciton absorption and emission bands are formed and the excitation energy can move along the chain ... 

The role of disorder in the photophysics of conjugated polymers has been extensively described by the work carried out in Marburg by H. Bassler and coworkers. Based on ultrafast photoluminescence (PL) (15], field-induced luminescence quenching [16J and site-selective PL excitation [17], a model for excited state thermalizalion was proposed, which considers interchain exciton migration within the inhomogenously broadened density of states. We will base part of the interpretation of our results in m-LPPP on this model, which will be discussed in some detail in Sections 8.4 and 8.6. 

An approach for improving the response of conjugated polymcr/fullerene bilayer devices, which is based on an additional excitonic middle layer inserted into the D-A interface, was suggested by Yoshino el al. [94. In the middle layer light absorption produces electron-hole pairs, which migrate towards the interlace and... 

Strong exciton splitting, e.g., 1000 cm-1, indicates extremely high rates of energy migration in a lattice. Even exciton splittings of 10cm 1... 

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