Journal
ACS NANO
Volume 13, Issue 11, Pages 12621-12629Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.9b04085
Keywords
2D hybrid perovskites; dielectric confinement; hot carrier cooling; nonadiabatic molecular dynamics; electron-phonon coupling
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Funding
- King Abdullah University of Science and Technology (KAUST)
- Georgia Research Alliance
- Vasser-Woolley Foundation
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Hot carrier (HC) cooling is a critical photophysical process that significantly influences the optoelectronic performance of hybrid perovskite-based devices. The hot carrier extraction at the device interface is very challenging because of its ultrashort lifetime. Here, ultrafast transient reflectance spectroscopy measurements and time -domain ab initio calculations show how the dielectric constant of the organic spacers can control and slow the HC cooling dynamics in single -crystal 2D Ruddlesden-Popper hybrid perovskites. We find that (EA)(2)PbI4 (EA = HOC2H4NH3+) that correspond to a high dielectric constant organic spacer has a longer HC cooling time compared to that of (AP)(2)PbI4 (AP = HOC3H6NH3+) and (PEA)(2)PbI4 (PEA = C6H5C2H4NH3+). The slow HC relaxation process in the former case can be ascribed to a stronger screening of the Coulomb interactions, a small nonradiative internal conversion within the conduction bands, as well as a weak electron -phonon coupling. Our findings provide a strategy to prolong the hot carrier cooling time in low-dimensional hybrid perovskite materials by using organic spacers with reduced dielectric confinement.
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