Temperature-induced shift of the exciton absorption band in InP/ZnS quantum dots

Abstract

Using the second-order derivative spectrophotometry method, we have determined the energy of optical transitions of colloidal InP/ZnS core-shell quantum dots at room temperature: E1 = 2.60 eV corresponds to a first exciton absorption peak of the InP core, E2 = 4.70 eV appears to meet the processes in the ZnS shell. We have investigated E1(T) temperature dependence within 6.5 - 296 K range for the first time. The obtained experimental data have been approximated by means of a linear model and Fan's expression. Also, it has been shown that the interaction between excitons and longitudinal acoustic phonons causes the energy E1 to change with temperature. In this case, the peak's FWHM remains invariant and amounts to 0.39 eV, which indicates the inhomogeneous broadening character and a high degree of static disorder in the ensemble of the quantum dots studied. © 2017 Optical Society of America.