LITVIN Aleksandr Saint Petersburg National Research University of Information Technologies, Mechanics and Optics

Temperature Dependences of Spectral and Kinetic Properties of PbS QD Photoluminescence

Co-authors PARFENOV Peter. S., USHAKOVA Elena V., GAMBOA Ana L. Simões, FEDOROV Anatoly V., BARANOV Alexander V.

Variation of spectral and kinetic properties of photoluminescence (PL) of PbS quantum dots (QDs) with temperature has to be study for further design of QD-based devices operating at reduced temperatures. Shift of the PL peak position and modification of the PL dynamics may change an efficiency of physical processes which are responsible for functioning of different appliances. For example, shift of PL band with temperature may significantly increase or decrease an efficiency of devices which exploit fluorescence resonance energy transfer (FRET) process. Moreover, if PL and absorption bands have different coefficients of temperature shift, we have a possibility to tune a spectral overlap between them, varying temperature. In the present work we performed steady-state and transient PL analysis of 3.2–6.9 nm QDs in a porous matrix in the temperature range of 77–300 K. We found up to 2 PL components in PbS QDs PL spectra for QDs of different size and estimated temperature coefficients of PL peak position shift for each one. Obtained temperature coefficients and their size-dependencies differ for these PL components due to the different origin of corresponding electronic states. According to the spectral data, temperature dependence of PL lifetime was explained using the model with two emissive low energy electronic states. These states are coupled with nonradiative transitions of excitons; besides, efficiency of the transition with energy increase depends on the temperature, leading to strong variation of PL lifetime with temperature.

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