Exciton splitting in thin-crystal 2D layered hybrid perovskites

Angelica Simbula^a, Luyan Wu^a, Fang Liu^b, Riccardo Pau^a^,^c, Selene Matta^a, Federico Pitzalis^a, Stefano Lai^a, Andrea Mura^a, Daniela Marongiu^a, Francesco Quochi^a, Michele Saba^a, Giovanni Bongiovanni^a

^aDipartimento di Fisica, Università di Cagliari - Cittadella Universitaria SP Monserrato-Sestu km 0.700, 09042 (CA) Italy

^bSchool of Environmental Science and Engineering, Frontiers Science Center for Transformative Molecules, Shangai Jiao Tong University, Shangai 200240, China

^cZernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4,09747 AG Groningen, The Netherlands

Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS23 & Sustainable Technology Forum València (STECH23) (MATSUS23)

#2DPERO - 2D Perovskites: Synthesis, Properties, and Applications

VALÈNCIA, Spain, 2023 March 6th - 10th

Organizers: Simon Kahmann and Loreta Muscarella

Oral, Angelica Simbula, presentation 148
DOI: https://doi.org/10.29363/nanoge.matsus.2023.148
Publication date: 22nd December 2022

Among hybrid perovskites (HP), 2D are playing a major role in many optoelectronics applications including solar cells, thanks also to their stabilizing effect. Despite their huge success, the dynamics of photogenerated carriers in these materials still needs to be fully assessed. In this work we report the result of ultrafast optical spectroscopy measurement in “tandem” configuration, combining transient absorption and time resolved photoluminescence in the same excitation conditions, as already applied to 3D and 2D HP thin films [1]. To get clearer information about intrinsic property, for the first time we apply our technique on single crystals of 2D HP (phenethylammonium (PEA)2PbI4), comparing nonresonant excitation, generating hot carriers, with resonant excitation, directly injecting cold excitons in the material. The results of our measurements show that both in the tihn film and in the crystal the photophysics consists in an initial massive formation of excitons, followed by a spontaneous ultrafast exciton splitting, occuring on a sub ps timescale. The evidences of this phenomenon are shown both in thin film and crystals wiht different excitation condition, eventually at low temperature, demonstrating that is an intrinsic effect. We believe that this results provide a better understanding in the photophysics laying under the exceptional optoelectronic properties of 2D HPs.

References:

[1] Simbula, A., Pau, R., Wang, Q., Liu, F., Sarritzu, V., Lai, S., Lodde, M., Mattana, F., Mula, G., Geddo, A., Spanopoulos, I. D., Kanatzidis, M. G., Marongiu, D., Quochi, F., Saba, M., Mura, A., Bongiovanni, G., Polaron Plasma in Equilibrium with Bright Excitons in 2D and 3D Hybrid Perovskites. Adv. Optical Mater. 2021, 9, 2100295

Acknowledgements:

The authors acknowledge CeSAR—Centro Servizi di Ateneo per la Ricerca—at the Università degli Studi di Cagliari
Fondazione di Sardegna through project 2F20000210007 “Perovskite materials for photovoltaics.”
PON “Ricerca e Innovazione” 2014–2020—Fondo sociale europeo, Attraction and International Mobility—Codice AIM1809115 Num. Attività 2, Linea 2.1.

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