We report on the temperature dependence of the photoluminescence (PL) spectrum and of the PL relaxation dynamics for colloidal $\mathrm{Cd}\mathrm{Se}∕\mathrm{Zn}\mathrm{S}$ core/shell quantum dots (QDs) embedded in an inert polystyrene matrix. We demonstrate that the confinement energy in the QDs is independent of the temperature. The coupling with both acoustic and optical phonons is also studied. Quantum confinement results in a strong increase of the exciton–acoustic-phonon coupling constant, up to $71\mu \mathrm{eV}∕\mathrm{K}$, and in a reduced exciton–longitudinal-optical (LO)-phonon coupling constant, down to $21\mathrm{meV}$, with respect to bulk CdSe. In addition, we demonstrate that the main nonradiative process that limits the quantum efficiency of the QD at room temperature is the thermal escape from the dot assisted by scattering with four LO phonons. Thermally activated trapping in surface states is also observed at low temperature, with an activation energy of about $15\mathrm{meV}$.

We show that all possible binary combinations of molecules from four different families of organics—a diamine derivative, N,N^′-bis(3methylphenyl)-N,N^′-diphenylbenzidine, an oxidiazole derivative, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, a substituted thiophene dioxide, 2,5-bis(trimethylsilyl thiophene)-1,1-dioxide, and poly(9-vinylcarbazole)—produce white or near-white emission. We suggest that this is due to exciplex formation, and that this is likely to be a general phenomenon for blends of blue-emitting aromatic organics. This implies that films of spin-coated blends of blue-emitting organics represent a general, simple, and cheap route to white-emitting organic light-emitting diodes.

We have studied the interactions in the solid phase between a blue-light-emitting organic conjugated polymer {poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-co-(9,ethyl-3,6-carbazole)]} and colloidal $\mathrm{CdSe}∕\mathrm{ZnS}$ core shell quantum dots. We demonstrate by time resolved photoluminescence measurements that efficient Förster energy transfer takes place from the polymer acting as the donor and the $\mathrm{CdSe}∕\mathrm{ZnS}$ dots, acting as the acceptors. A Förster radius of about $80\pm 15\mathrm{\AA }$ is extracted from the analysis of the relaxation dynamics based on the solution of the donor-acceptor coupled rate equations. This value is in good agreement with the value extracted from the steady state spectra and indicates that efficient energy tranfer from a polymeric host to a nanocrystal guest can occur. Our results are relevant to the application of hybrid organic/inorganic systems to light-emitting devices.