期刊
ACS NANO
卷 -, 期 -, 页码 -出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.2c12373
关键词
hot carriers; two-dimensional perovskites; nanoplatelets; nanocrystals; ultrafast spectroscopy
In this study, the relaxation of hot carriers in lead halide perovskites (LHPs) and the role of quantum confinement in nanosystems were examined. Ultrafast pump-push-probe spectroscopy was used to study carrier cooling in different size-controlled LHP nanomaterials. The results showed that dimensional confinement has a significant impact on carrier-phonon and carrier-carrier interactions, highlighting its potential for engineering LHP optoelectronic materials.
The relaxation of the above-gap (hot) carriers in lead halide perovskites (LHPs) is important for applications in photovoltaics and offers insights into carrier-carrier and carrier-phonon interactions. However, the role of quantum confinement in the hot carrier dynamics of nanosystems is still disputed. Here, we devise a single approach, ultrafast pump- push-probe spectroscopy, to study carrier cooling in six different size-controlled LHP nanomaterials. In cuboidal nanocrystals, we observe only a weak size effect on the cooling dynamics. In contrast, two-dimensional systems show suppression of the hot phonon bottleneck effect common in bulk perovskites. The proposed kinetic model describes the intrinsic and density-dependent cooling times accurately in all studied perovskite systems using only carrier-carrier, carrier-phonon, and excitonic coupling constants. This highlights the impact of exciton formation on carrier cooling and promotes dimensional confinement as a tool for engineering carrier-phonon and carrier-carrier interactions in LHP optoelectronic materials.
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