Long-living nonlinear behavior in CsPbBr3 carrier recombination dynamics

• Published in: Nanophotonics (Berlin, Germany) Vol. 8; no. 9; pp. 1447 - 1455
• Main Authors: Gabelloni, Fabio, Biccari, Francesco, Falsini, Naomi, Calisi, Nicola, Caporali, Stefano, Vinattieri, Anna
• Format: Journal Article
• Language: English
• Published: Berlin De Gruyter 2019; Walter de Gruyter GmbH
• Subjects: Auger effect; Augers; Bias; Carrier recombination; Continuous radiation; Cooling rate; Cryogenic temperature; CsPbBr; cspbbr3; Energy recovery; Excitation; Excitons; inorganic perovskites; Microcrystals; non-linearity; Photoluminescence; Recovery time; Resonance; Temperature dependence; thermalization; Thermalization (energy absorption); Time constant; time-resolved optical spectroscopy
• ISSN: 2192-8606; 2192-8614
• DOI: 10.1515/nanoph-2019-0013

By means of time-resolved photoluminescence (TR-PL) spectroscopy, we present a detailed investigation of the carrier relaxation dynamics in a CsPbBr bulk sample and microcrystal ensemble at cryogenic temperature on a picosecond time scale. We provide evidence of a long temperature-dependent cooling rate for the excitons and free carriers population, with an initial cooling time constant of a few tens of picoseconds. A relaxation bottleneck in the thermalization process was found that cannot be explained by the Auger effect or hot phonon population, since we address a very low excitation regime, not commonly investigated in literature, where such processes are not effective. Adding a continuous wave optical bias to the picosecond excitation, we probed the photoinduced PL decrease of the localized states and the photoinduced PL increase of the population in the high energy states. A long recovery time from the photoinduced PL decrease was found for localized states and quite significant differences were detected, depending on the resonance/off resonance bias used in the experiment.