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.

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

RICHTER, JOHANNES MARTIN;Branchi, Federico;VALDUGA de ALMEIDA CAMARGO, FRANCO;Cerullo, Giulio;DESCHLER, FELIX ALEXANDER
2017-01-01

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.
Chemistry (all); Biochemistry, Genetics and Molecular Biology (all); Physics and Astronomy (all)
File in questo prodotto:
File Dimensione Formato  
NatComm_Richter_2017.pdf

accesso aperto

: Publisher’s version
Dimensione 1.14 MB
Formato Adobe PDF
1.14 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1053297
Citazioni
  • ???jsp.display-item.citation.pmc??? 20
  • Scopus 129
  • ???jsp.display-item.citation.isi??? 135
social impact