Observation of a phonon bottleneck in copper-doped colloidal quantum dots.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31586066.
- Also identified by DOI 10.1038/s41467-019-12558-y and PMC identifier 6778069.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Hot electrons can dramatically improve the efficiency of solar cells and sensitize energetically-demanding photochemical reactions. Efficient hot electron devices have been hindered by sub-picosecond intraband cooling of hot electrons in typical semiconductors via electron-phonon scattering. Semiconductor quantum dots were predicted to exhibit a "phonon bottleneck" for hot electron relaxation as their quantum-confined electrons would couple very inefficiently to phonons. However, typical cadmium selenide dots still exhibit sub-picosecond hot electron cooling, bypassing the phonon bottleneck possibly via an Auger-like process whereby the excessive energy of the hot electron is transferred to the hole. Here we demonstrate this cooling mechanism can be suppressed in copper-doped cadmium selenide colloidal quantum dots due to femtosecond hole capturing by copper-dopants. As a result, we observe a lifetime of ~8.6 picosecond for 1P<sub>e</sub> hot electrons which is more than 30-fold longer than that in same-sized, undoped dots (~0.25 picosecond).