This work is devoted to the analysis of the voltage dependence of the luminescence of n-type nanoporous films. The correlations between the behaviour of the photoluminescence and electroluminescence signal obtained from the same sample allow one to confirm that the emission quenching mechanism is related to the injection of electrons into the crystallites. When the samples are partially oxidised, the injection conditions are strongly modified, leading to significant changes in the observed voltage dependence of the emission.