Hot-hole cooling controls the initial ultrafast relaxation in methylammonium lead iodide perovskite

Hedley, G. J. , Quarti, C., Harwell, J., Prezhdo, O. V., Beljonne, D. and Samuel, I. D. W. (2018) Hot-hole cooling controls the initial ultrafast relaxation in methylammonium lead iodide perovskite. Scientific Reports, 8, 8115. (doi: 10.1038/s41598-018-26207-9) (PMID:29802309) (PMCID:PMC5970208)

Abstract

Understanding the initial ultrafast excited state dynamics of methylammonium lead iodide (MAPI) perovskite is of vital importance to enable its fullest utilisation in optoelectronic devices and the design of improved materials. Here we have combined advanced measurements of the ultrafast photoluminescence from MAPI films up to 0.6 eV above the relaxed excited state with cutting-edge advanced non-adiabatic quantum dynamics simulations, to provide a powerful unique insight into the earliest time behaviour in MAPI. Our joint experimental-theoretical approach highlights that the cooling of holes from deep in the valence band to the valence band edge is fast, occurring on a 100–500 fs timescale. Cooling of electrons from high in the conduction band to the conduction band edge, however, is much slower, on the order of 1–10 ps. Density of states calculations indicate that excited states with holes deep in the valence band are greatly favoured upon photoexcitation, and this matches well with the fast (100–500 fs) formation time for the relaxed excited state observed in our ultrafast PL measurements. Consequently we are able to provide a complete observation of the initial excited state evolution in this important prototypical material.

• Item Type: Articles
• Additional Information: We are grateful to the EPSRC (grants EP/J009016 and EP/L017008) and the European Research Council (grant 321305) for financial support. The work was also supported by the Interuniversity Attraction Pole program of the Belgian Federal Science Policy Office (PAI 6/27) and FNRS-F.R.S. Computational resources have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifique de Belgique (F.R.S.-FNRS) under Grant No. 2.5020.11. DB is a FNRS Research Director. IDWS acknowledges a Royal Society Wolfson Research Merit Award. O.V.P. acknowledges support of the U.S. National Science Foundation, award number CHE-1565704.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hedley, Dr Gordon
• Authors: Hedley, G. J., Quarti, C., Harwell, J., Prezhdo, O. V., Beljonne, D., and Samuel, I. D. W.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Scientific Reports
• Publisher: Nature Research
• ISSN: 2045-2322
• ISSN (Online): 2045-2322
• Copyright Holders: Copyright © 2018 The Authors
• First Published: First published in Scientific Reports 8:8115
• Publisher Policy: Reproduced under a Creative Commons License