Photoluminescence of CdTe colloidal quantum wells in external electric field

We investigated emissive properties of CdTe colloidal quantum wells (CQWs) in applied electric fields in the range of 0-90 kV/cm. Photoluminescence spectra and time-resolved intensities of the excitonic peak were studied. The emission was centered at 2.47 eV with a width of 40 meV. No visible broadening or redshifts were detected in the whole range of applied fields. We obtained the dependencies of integrated intensity and maximum intensity of interband luminescence on the magnitude of applied electric field with the decrease of these characteristics by 15-20% at 90 kV/cm due to field-controlled charge carrier separation. Deceleration of the radiative decay rates with increasing electric field provides the evidence of field-controlled temporary exciton storage as two-fold increase of the number of photons registered in the 1-40 ns time range is observed. This assertion is also confirmed by the growth of the luminescence integrated intensity in the electric fields in the range 30-60 kV/cm. These findings are an important step toward understanding of the influence of electric fields on the operation of hybrid organic-inorganic LEDs with CQW-based emissive layers.