Photoluminescence thermal quenching of yellow-emitting InP/ZnS quantum dots

Photoluminescence of the QDs ensemble with an average particle size of 2.1 nm are investigated in 6.5–296 K range. A low-energy shoulder appears in the spectrum with temperature decrease and at 6.5 K two maxima with energies Ed = 2.07 eV and Ex = 2.35 eV are observed. These bands are shown to stem from defect-related and exciton transitions. Temperature shift of the latter is caused by interaction with effective phonons of 18 meV energy. The spectrum is suggested to experience strong inhomogeneous broadening. A Stokes shift of the Ex peak drops from 360 to 330 meV with temperature increase implying exciton fine structure. An analysis of quenching processes indicates the dominant contribution of the Ed band and the presence of two nonradiative relaxation channels with Eq1 = 95 meV and Eq2 = 16 meV activation energies. Emission chromaticity changes from yellow with (0.42, 0.54) coordinates to yellow-green with (0.34, 0.60) ones upon heating in the specified temperature range.Photoluminescence of the QDs ensemble with an average particle size of 2.1 nm are investigated in 6.5–296 K range. A low-energy shoulder appears in the spectrum with temperature decrease and at 6.5 K two maxima with energies Ed = 2.07 eV and Ex = 2.35 eV are observed. These bands are shown to stem from defect-related and exciton transitions. Temperature shift of the latter is caused by interaction with effective phonons of 18 meV energy. The spectrum is suggested to experience strong inhomogeneous broadening. A Stokes shift of the Ex peak drops from 360 to 330 meV with temperature increase implying exciton fine structure. An analysis of quenching processes indicates the dominant contribution of the Ed band and the presence of two nonradiative relaxation channels with Eq1 = 95 meV and Eq2 = 16 meV activation energies. Emission chromaticity changes from yellow with (0.42, 0.54) coordinates to yellow-green with (0.34, 0.60) ones upon heating in the specified temperature range.