A comparative study on temperature-dependent photoluminescence (PL) of InGaN/GaN multiple-quantum-well (MQW) violet-blue light-emitting diodes (LEDs) is presented. For the violet-blue LEDs, the peak energy exhibits a well-established S-shaped temperature behavior. The redshift at low temperatures is explained by carrier relaxation into lower energy states, which leads to dominant radiative recombination occurring mostly at localized states. The temperature-dependent PL was attributed to the localization effects in the MQW region of the samples. Up to three phonon replicas were also observed in the side-band of the quantum well luminescence with an energy separation similar to the GaN longitudinal-optical (LO)-phonon energy (similar to 91 meV). The properties of LO-phonon satellites were investigated as a function of the indium fraction and the well-width in a active layer at low temperatures. (C) 2009 Elsevier Ltd. All rights reserved.