Cs2SnI6 nanoparticles: a lead-free perovskite material with outstanding nonlinear properties
Isaac Suárez a, Juan P. Martínez-Pastor a, Marek F. Oszajca b, Norman A. Lüchinger b, Brian Graves b, Said Agouram a, Carles Milián c, Albert Ferrando a
a Institut de Ciències de Materials (ICMUV), c/ Catedràtic José Beltrán, 2, Paterna (València), Spain
b Avantama Ltd, Staefa, Switzerland, Laubisrütistrasse, 50, Stäfa, Switzerland
c Polytechnic University of Valencia
Proceedings of Sustainable Metal-halide perovskites for photovoltaics, optoelectronics and photonics (Sus-MHP)
València, Spain, 2022 December 12th - 13th
Organizers: Teresa S. Ripolles and Hui-Seon Kim
Oral, Isaac Suárez, presentation 026
Publication date: 15th November 2022

Lead-free metal halide perovskites (LFP) have emerged as a promising family of semiconductors to develop a new green technology for optoelectronics. This manuscript demonstrates that Cs2SnI6 (a vacancy ordered double perovskite) nanocrystals (NCs) present an extraordinary self-defocusing response not yet observed up to now. The near field characterization of nanosecond pulses traversing the cuvette filled by a solution of NCs indicates that there is a certain threshold of excitation intensity from which the width of the beam experiences a fast growth with the formation of the rings. Furthermore, the dependence of the traversing beam with the intensity and concentration of nanocrystals in the solvent indicates four different regions where the beam broads, diffracts on concentric rings or saturates. This complex behavior is reproduced by a nonlinear beam propagation method (BPM) incorporating a particular nonlinearity based on two saturation Kerr effects not observed up to now. The associated refractive index change indicates (Δn) a giant self-defocusing response, Δn=-0.05, whose magnitude is tunned with the intensity and concentration. Moreover, under certain conditions Δn exhibits a crossover from self-defocusing to self-focusing with the propagation distance, leading to a self-induced waveguide. This crossover between low-to-giant negative Kerr effect is perfectly reversible and can be explained by a laser trapping of NCs that increases the effective concentration of NCs.  The strong Kerr nonlinearity and this unexpected low-to-giant negative Kerr transition has never been observed and can be the base towards the optical signal processing fascinating opportunities in sensing and light–matter interactions for a future ecofriendly photonic technology.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 62656 (project DROP-IT) and by the Spanish MINECO through projects no. TEC2017-86102-C2-1-R and PID2020-120484RB-I00.

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