Hot Carrier Recombination in Lead Halide Perovskite Nanocrystals

Andreas Manoli^a, Paris Papagiorgis^a, Sozos Michael^a, Caterina Bernasconi^b^,^c, Maryna I. Bodnarchuk^c, Maksym V. Kovalenko^b^,^c, Andreas Othonos^d, Grigorios Itskos^a

^aExperimental Condensed Matter Physics Lab, Department of Physics, University of Cyprus, Cyprus

^bETH Zurich, Laboratory of Inorganic Chemistry, Department of Chemistry & Applied Biosciences, Vladimir-Prelog-Weg, 1, Zürich, Switzerland

^cLaboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland, Überland Strasse, 129, Dübendorf, Switzerland

^dLaboratory of Ultrafast Science, Department of Physics University of Cyprus, Nicosia, Cyprus

Proceedings of Internet Conference for Quantum Dots (iCQD)

Online, Spain, 2020 July 14th - 17th

Organizers: Quinten Akkerman, Raffaella Buonsanti, Zeger Hens and Maksym Kovalenko

Poster, Andreas Manoli, 083
Publication date: 3rd July 2020

ePoster:

Lead halide perovskite nanocrystals (LHP NCs) have emerged as promising building blocks for optoelectronic devices due to their outstanding properties. Apart from their tunable emission across the visible with narrow linewidth, high emission quantum yields and their defect tolerant defect-tolerant electronic structure, LHP NCs display efficient slowdown of the hot carrier cooling certifying them as promising materials for hot carrier absorber and emitter applications such as hot carrier solar cells.

In this work [1] we present a comprehensive study of the optical properties of hot electron-hole gas in colloids and films of three representative LHP NCs based on the inorganic CsPbBr₃ and the hybrid FAPbBr₃ and FAPbI₃ materials. We employ a series of experiments in the high excitation density regime, where the average carrier occupancy per NC is larger than 1 and probe the nature/characteristics of the recombinations from steady state to the femtosecond regime.

In all systems in the ultrafast regime we observed evidence of prolonged carrier cooling. For the case of FAPbI₃ NCs though the retardation of the carrier relaxation appears pronounced. Previous work [2] demonstrated the presence of long lived hot carriers in such NCs. By extending the work to significantly higher fluences where the number of carriers per NC is larger than 2, the impact of hot carriers on the emission becomes evident, resulting in some cases in an oscillatory transient behavior and suppression of the ASE in favor of higher energy emission from hot carriers and recombination from localized defect states above the band-edge.

We probe the energetics and dynamics of the aforementioned radiative channels in FAPbI₃NC films and colloids. Finally we probe the impact of experimental and material factors on the mechanisms such as temperature, material purity, film quality and excitation pulse duration and wavelength.

References:

[1] Papagiorgis P.; Manoli A.; Michael S.; Bernasconi C.; Bodnarchuk M. I.; Kovalenko M. V.; Othonos A.; Itskos G. Unraveling the Radiative Pathways of Hot Carriers upon Intense Photoexcitation of Lead Halide Perovskite Nanocrystals, ACS Nano,2019,13,5,5799-5809

[2] Papagiorgis P.; Protesescu, L.; Kovalenko M. V.; Othonos, A.; Itskos, G., Long-lived hot carriers in formamidinium lead iodide nanocrystals, J. Phys. Chem. C , 2017, 121, 12434−12440.

Acknowledgements:

Research Promotion Foundation of Cyprus under the “NEW STRATEACSGIC INFRASTRUCTURE UNITS-YOUNG SCIENTISTS”

Programme INFRASTRUCTURES/1216/0004

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