期刊
ACS NANO
卷 17, 期 7, 页码 6638-6648出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.2c12373
关键词
hot carriers; two-dimensional perovskites; nanoplatelets; nanocrystals; ultrafast spectroscopy
This study investigates the carrier cooling process in size-controlled lead halide perovskite nanomaterials using ultrafast pump-push-probe spectroscopy. The results show that there is only a weak size effect on the cooling dynamics in cuboidal nanocrystals, while the hot phonon bottleneck effect commonly observed in bulk perovskites is suppressed in two-dimensional systems.
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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