Semiconductor-polymer composite with strong nonlinear optical properties

Photoluminescence (PL) characteristics of CdTe nanocrystals (NCs) adsorbed into polymer films are presented compared to the PL of bulk CdTe. Using the dependence of PL on excitation power we determined the carrier lifetime at 80K which indicates that carrier trapping in surface and polymer states was the main decay mechanism of excitation. The occurrence of at least two deep defect induced luminescence bands in CdTe NCs was demonstrated for the first time. Our investigation also revealed changes in PL properties induced by the visible light irradiation or by the preparation conditions. These results were explained by an increase of nonradiative recombination in the surface states of NCs and in the polymer.