ELECTROLUMINESCENCE IN THIN SOLID FILMS OF CLOSELY-PACKED CDS NANOCRYSTALS

An all-inorganic structure has been prepared with thin 200-300 nm soli d films of closely packed 1.6-1.8 nm CdS nanocrystals sandwiched betwe en ITO and Ag contact layers and electroluminescence behavior has been examined at room temperature. The spectral position of the electrolum inescence band is voltage-dependent and exhibits blue shift at increas ed bias demonstrating the color tunability of electroluminescence outp ut. Voltage-current and bias-intensity curves indicate the hopping con ductivity of carriers through the nanogranular semiconductor film. The mechanism of electroluminescence in nanogranular CdS film is suggeste d to be an impact ionization of deep radiative centers in CdS nanocrys tals. (C) 1998 Elsevier Science B.V. All rights reserved.