Electric Field Effects on Photoluminescence of CdSe Nanoparticles in a PMMA Film

External electric field effects on spectra and decay of photoluminescence (PL) as well as on absorption spectra were measured for CdSe nanoparticles in a poly(methyl methacrylate) (PMMA) film. Electrophotoluminescence (E-PL) spectra as well as electroabsorption spectra show a remarkable Stark shift which depends on the particle size, indicating a large electric dipole moment in the first exciton state. The E-PL spectra also show that PL of CdSe is quenched by application of electric fields, and the magnitude of the field-induced quenching becomes larger with increasing size. The PL decay profiles observed in the absence and presence of electric field show that the field-induced quenching of PL mainly originates from the field-induced decrease in population of the emitting state prepared through the relaxation from the photoexcited state.