Ultrafast carrier thermalization in lead iodide perovskite probed with two-dimensional electronic spectroscopy.

ABSTRACT: In band-like semiconductors, charge carriers form a thermal energy distribution rapidly after optical excitation. In hybrid perovskites, the cooling of such thermal carrier distributions occurs on timescales of about 300?fs via carrier-phonon scattering. However, the initial build-up of the thermal distribution proved difficult to resolve with pump-probe techniques due to the requirement of high resolution, both in time and pump energy. Here, we use two-dimensional electronic spectroscopy with sub-10?fs resolution to directly observe the carrier interactions that lead to a thermal carrier distribution. We find that thermalization occurs dominantly via carrier-carrier scattering under the investigated fluences and report the dependence of carrier scattering rates on excess energy and carrier density. We extract characteristic carrier thermalization times from below 10 to 85?fs. These values allow for mobilities of 500?cm2?V-1?s-1 at carrier densities lower than 2?×?1019?cm-3 and limit the time for carrier extraction in hot carrier solar cells.Carrier-carrier scattering rates determine the fundamental limits of carrier transport and electronic coherence. Using two-dimensional electronic spectroscopy with sub-10?fs resolution, Richter and Branchi et al. extract carrier thermalization times of 10 to 85?fs in hybrid perovskites.

SUBMITTER: Richter JM 

PROVIDER: S-EPMC5575115 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature