Lead-free orange to red light emitters based on two- dimensional TEA2SnX4 micro and nanocrystals
Raul Ivan Sanchez Alarcon a, Omar Eduardo Solís Luna a, María Cristina Momblona Rincon a, Teresa Ripolles Sanchis a, Rafael Abargues a, Pablo Pérez Boix a, Vladimir Chirvony a, Juan Martínez Pastor a
a UMDO Instituto de Ciencia de los Materiales- Universidad de 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, Raul Ivan Sanchez Alarcon, presentation 016
Publication date: 15th November 2022

Currently, two-dimensional tin-based halide perovskites (2D- THP) have drawn attention owing to improved ambiental stability, low toxicity, thickness dependant optical properties, and high exciton energy binding [1, 2], showing great potential to be exploited as lead-free visible light emitters on optoelectronic and photovoltaic devices [3]. Moreover, optical properties and carrier mobility can be adjusted as a function of organic cations length, opening a full gamut of possibilities for the design and development of new Ruddlesden Popper perovskite nanostructures [4]. Among 2D- THPs reported now, TEA2SnI4 perovskite has shown some interest in LED applications because of its high exciton energy binding (calculated in 51.1 meV) and low exciton- phonon interactions [5]. In the literature, 2D- TEA2SnI4 has been prepared by LARP and anti-solvent approaches, showing a PLQY record of 18.85% and 23 % on nanodisks solution [6,7] and thin film [8] respectively. Although, the development of nano- and microcrystals have not been completed and explored for this material because of uncontrollable crystallization rate, the formation of native defects, and poor passivated surfaces [9]. Moreover, the synthesis and physical properties of TEA2SnBr4 and TEA2SnCl4 nanomaterials have not been reported yet. For the first time, TEA2SnX4 (X= Cl, Br, I) micro and nanocrystals were synthesized by the hot injection method. We determine that the size and physical properties of TEA2SnX4 micro and nanocrystals are determined by parameters such as temperature and molar ratio of precursors. For the case of TEA2SnCl4 and TEA2SnBr4, we observe a broad PL band emission centered at 595 nm and 608 nm respectively. In both cases, we recorded a high Stokes shift (approximately 300 nm), and hence, it might be indicative of self-trapped excitons recombination mechanisms. The maximum PLQY measured in these samples was 50 % for TEA2SnBr4, 20 % for TEA2SnCl4, and 3% for TEA2SnI4. For TEA2SnI4 micro and nanocrystals, optical properties are a bit similar to the reported in the literature [6,7], represented by a sharp band emission centered at 647 nm with an FWHM = 38 nm at 300 K. PL and TRPL measurements were conducted at different temperatures to understand the optical properties of TEA2SnX4 micro and nanocrystals. In all cases, we observe an X-ray diffraction pattern characterized by strong reflections which is consistent with the quantum well like the structure of 2D hybrid tin halide perovskites . Additionally, 1H,13C and 119Sn nuclear magnetic resonance, Raman spectroscopy, X- ray photoelectron spectroscopy and transmision electron microscopy measurements were carried out.

This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 862656 (project DROP-IT), by the Spanish MICINN through project no. PID2020-120484RB. We acknowledge the support of the Spanish MINECO through the project Nirvana (no. PID2020-119628RB-C31) by MCIN/AEI/10.13039/501100011033 and the CIDEGENT contract.

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