Temperature Dependence of the Photoluminescence of InP/ZnS Quantum Dots

Colloidal InP/ZnS core−shell nanocrystals were prepared via a non-organometallic approach in a non-coordinating solvent. The energy shift and line broadening of the e1−h1 (HOMO−LUMO) transition have been investigated using photoluminescence studies in the temperature range 300−525 K. The energy of the e1−h1 transition decreases with increasing temperature due to the exciton−phonon interaction and has been fitted to phenomenological equations, from which the Huang−Rhys factor and the average phonon energy are extracted. The photoluminescence line width increases with temperature and is analyzed with respect to the standard equation describing the temperature dependence of the width of the lowest-lying exciton. The results show that, in the temperature range 300−525 K, the variation of both the energy band gap and the photoluminescence line broadening are predominantly due to coupling of the e1−h1 transition to the acoustic phonons.