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S. Kahmann,O. Nazarenko,S. Shao, O. Hordiichuk, M. Kepenekian, J. Even, M. V. Kovalenko, G. R. Blake, M. A. Loi,

Negative Thermal Quenching in FASnI3 Perovskite Single Crystals and Thin Films

ACS Energy Lett. 5, 2512 (2020). 

DOI: 10.1021/acsenergylett.0c01166

Formamidinium tin triiodide (FASnI3) is a strong contender for sustainable harvesting of solar energy and further optoelectronic applications. So far, only a few studies have considered its fundamental structure–property relationships, given the challenge of ensuring a high material quality. In a concerted effort, we here study high-quality FASnI3 single crystals through a combination of X-ray crystallography, density-functional-theory-based electronic structure calculations, and photoluminescence spectroscopy from room temperature down to 4K. The luminescence exhibits irregular trends upon cooling with a generally strong intensity increase, but a range of negative thermal quenching, leading to an intensity maximum around 185K which is absent in low-quality samples. Differences in the photoluminescence peak position and density-functional-theory-calculated band-gap energies highlight the importance of dynamic processes to the observable properties of FASnI3. The presented data offer deeper insight into the temperature-dependent characteristics of this halide perovskite and present opportunities for future exploration of its optoelectronic properties.


Eduardo Lpez-Fraguas, Sofa Masi, Ivn Mora-Ser

Optical characterization of lead-free Cs2CnI6 double perovskite fabricated from degraded and reconstructed CsSnI3 films

J. Phys. Chem. Lett. 10, 6389−6398 (2019). 

DOI: 10.1021/acsaem.9b01827

Halide perovskites have experienced a huge development in the past years, but they still have two major challenges for their massive implantation: the long-term stability and the use of lead. One of the most obvious lead-free candidates to replace these perovskites is CsSnI3, but due to its poor environmental stability, it has been discarded for the fabrication of stable devices. Nevertheless, ambient degradation of CsSnI3 and ulterior reconstruction produce a relatively stable lead-free Cs2SnI6 double perovskite with interesting optical properties that have not been deeply characterized previously. In this work, the potential use for the optical properties of Cs2SnI6 is studied and compared with that of the most common halide perovskite, CH3NH3PbI3 (MAPbI3). The Cs2SnI6 films stayed in a standard atmosphere for a week without showing any signs of degradation. They also demonstrated better reflective behavior than MAPbI3 and higher absorption in the 650 and 730 nm spectral range, making this material interesting for the development of photodetectors in this region. This study demonstrates that Cs2SnI6 is a promising material for photodevices, as it highlights its main characteristics and optical parameters, giving an original view on the use of the double perovskite, but at the same time emphasizing the need to improve the electrical properties for the development of efficient optoelectronic devices.


Valencia, 17th October 2019

27th April 2020

19th November 2020

DROP-IT has received funding from the European Union’s Horizon 2020 FET-OPEN research programme under grant agreement No 862656.