The influence of external electric field was studied on the luminescence behavior of quantum-sized CdS and PbI2 nanocrystals, embedded in various polymeric films. The clear increase in the photoluminescence intensity from the quantum-sized particles was observed, as well as the spectral shift of photoluminescence bands. The mechanism proposed is based on the field-induced oxygen desorption from the nanocrystal surface which is the good photoluminescence inhibitor.