Abstract
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)2PbI4 (EA = HOC2H4NH3+) that correspond to a high dielectric constant organic spacer has a longer HC cooling time compared to that of (AP)2PbI4 (AP = HOC3H6NH3+) and (PEA)2PbI4 (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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 12621-12629 |
| Number of pages | 9 |
| Journal | ACS Nano |
| Volume | 13 |
| Issue number | 11 |
| DOIs | |
| State | Published - Oct 21 2019 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledgements: This work was supported by the King Abdullah University of Science and Technology (KAUST). The work at Georgia Tech was supported by the Georgia Research Alliance and the Vasser-Woolley Foundation. We acknowledge the Supercomputing Laboratory at KAUST for their computational and storage resources, as well as their gracious assistance. We also acknowledge Dr. J. Khan for the discussions.