posted on 2024-02-01, 20:15authored byClara Bujalance, Laura Caliò, Dmitry N. Dirin, David O. Tiede, Juan F. Galisteo-López, Johannes Feist, Francisco J. García-Vidal, Maksym V. Kovalenko, Hernán Míguez
Strong coupling between
lead halide perovskite materials and optical
resonators enables both polaritonic control of the photophysical
properties of these emerging semiconductors and the observation of
fundamental physical phenomena. However, the difficulty in achieving
optical-quality perovskite quantum dot (PQD) films showing well-defined
excitonic transitions has prevented the study of strong light–matter
coupling in these materials, central to the field of optoelectronics.
Herein we demonstrate the formation at room temperature of multiple
cavity exciton-polaritons in metallic resonators embedding highly
transparent Cesium Lead Bromide quantum dot (CsPbBr3-QD)
solids, revealed by a significant reconfiguration of the absorption
and emission properties of the system. Our results indicate that the
effects of biexciton interaction or large polaron formation, frequently
invoked to explain the properties of PQDs, are seemingly absent or
compensated by other more conspicuous effects in the CsPbBr3-QD optical cavity. We observe that strong coupling enables a significant
reduction of the photoemission line width, as well as the ultrafast
modulation of the optical absorption, controllable by means of the
excitation fluence. We find that the interplay of the polariton states
with the large dark state reservoir plays a decisive role in determining
the dynamics of the emission and transient absorption properties of
the hybridized light-quantum dot solid system. Our results should
serve as the basis for future investigations of PQD solids as polaritonic
materials.