Temperature effects on the vibrational properties of the Cs2SnX6 ‘defect’ perovskites (X = I, Br, Cl)

Mapping the Real-Time Vibrational Infrastructure of Cs2SnI6 Nanocrystals through Coherent Phonon Dynamics

“…Similar conclusions stand true for the other F 1u modes: “C–D” and “K–L” modes. The experimental findings obtained in our present investigation, thereby, suggest anharmonicity prevalent in the Sn–I cage in accordance with earlier reports which have predicted anharmonicity in this system . The vibrational feature at 108 cm –1 , a combination mode corresponding to the parent lattice modes at 29 and 84 cm –1 is a confirmation of this fact.…”

“…But the number of modes remains the same, and there is no emergence of new modes even at lower temperatures indicating that the crystals retain their highest possible symmetry, which is average cubic symmetry (Figure E). This immediate finding reconciles well with the temperature-dependent Raman investigations executed very recently by Belessiotis et al, where no impression of restructuring or phase transformation is noticeable in the acquired data . Our study indeed disproves any kind of phase transition that occurs along the range of investigated temperatures.…”

“…Also, there is no phonon softening observed in the residual vibrations drawn from the TA data for Cs 2 SnI 6 NCs upon subjecting its lattice to a wide range of temperatures (300–5 K). The results obtained are contrary with respect to the theoretically predicted phase transition at 44 and 137 K (Figure D) . If there would have been any transition into a lower symmetry phase, there should have been a higher number of Raman modes observable (nine, suggested by the irreducible representation from group theory analysis) .…”

“…It has emerged as a potential light-absorbing layer in photovoltaic (PV) devices because of its optimal energy band gap and high absorption coefficient. Photoconversion efficiency (PCE) exceeding 10% has already been reported for Cs 2 SnI 6 -based solar cells. − Indeed, it has also illustrated exotic candidature as a hole transporting layer. − Aside from the potent candidature displayed for solar cell applications, thermo-electrics is another such classified field where Cs 2 SnI 6 by virtue of its low thermal conductivity ( k ) has witnessed commendable success. , Such low magnitudes of “ k ” have often been linked to vibrational chaos stemming from anharmonicity in the lattice dynamics. − Even more, recent literature has attributed the photoconversion efficiencies of PV devices to lattice anharmonicity. − …”

Magnetic Metal Oxide-Based Photocatalysts with Integrated Silver for Water Treatment

“…The physicochemical characterization of materials, and especially compounds, is vital for their understanding [20,[128][129][130]. In general, for efficient magnetic/silver nanocomposites, a uniform positioning of the silver particles on the surface of the base magnetic material with low agglomeration is optimal [12,20].…”