Temperature-dependent dielectric properties of CsPb₂Br₅: a 2D inorganic halide perovskite

Abstract

Two dimensional (2D) CsPb2Br5 have been successfully synthesized via the chemical precipitation method. Detailed structural, morphological, optical, and dielectric studies of these materials have been performed. These 2D CsPb2Br5 plates (of thickness around 200-300 nm) are ascribed to a tetragonal lattice system with I4/mcm space group. The dielectric attributes such as dielectric constant, electrical modulus, loss factor, and the DC, and AC conductivities, are observed to be varying appreciably with temperature over an extensive frequency window of 10 Hz -50 MHz. The Nyquist plots are investigated using the Maxwell–Wagner equivalent circuit model, which shows the impact of grains and grain boundaries on the overall impedance. Both the free charge conductivity and space charge increase with an increment in temperature, as revealed from the modified Cole-Cole plot. The relaxation time and relaxation mechanism of 2D CsPb2Br5 are estimated using the Kohlrausch-Williams-Watts (KWW) equation. Variation in DC conductivity and relaxation time, as a function of temperature, closely resembles Arrhenius' behavior. Value of activation energy calculated from the DC conductivity corroborates with the same derived from relaxation time. The observation of high dielectric constant and nominal dielectric loss for CsPb2Br5 perovskite offers enormous potential in energy harvesting and storage devices.

High piezoresponse in low-dimensional inorganic halide perovskite for mechanical energy harvesting

“…These microplates are strongly oriented in a particular direction along [002], its second, third, and fourth-order planes. Due to lattice compression, the micro strain calculated in CsPb 2 Br 5 microplates is 0.21%, whereas the micro strain in CsPb 2 Br 5 nanoform synthesized in our prior study 36 was only 0.032%. For P–E loop comparison, the CsPb 2 Br 5 nanoplate was synthesized using the previously reported method.…”

“…3(a) shows the frequency-dependent dielectric permittivity for a temperature range of 313-473 K. The value of the dielectric permittivity decreases with the increase in frequency, and this can be attributed to the fact that the dipole moments are no longer capable of following the electric eld in the highfrequency region. 36 Fig. 3(b) shows that the temperaturedependent dielectric permittivity increases with the rise in temperature at a constant frequency.…”

“…For P-E loop comparison, the CsPb 2 Br 5 nanoplate was synthesized using the previously reported method. 36 The P-E loop of CsPb 2 Br 5 nanoplates gives a lossy loop with a tiny amount of polarization (Fig. S7: please see ESI †).…”

“…The CsPb 2 Br 5 crystallized in a two-dimensional tetragonal structure, with one Cs ion layer sandwiched between two Pb-Br layers. [36][37][38][39][40] Furthermore, unlike CsPbBr 3 , which has to be synthesized at a high temperature, CsPb 2 Br 5 may be easily produced at ambient temperature, making it an attractive contender for future uses.…”

High Ionic Conduction and Polarity-Induced Piezoresponse in Layered Bimetallic Rb4Ag2BiBr9 Single Crystals

“…Figure a demonstrates the variation of M′ (ω) as a function of ω in the temperature range of 303–463 K. The values of M′ (ω) are observed to be very low in the LF region; then, they start increasing with ω and finally attain the maximum saturated values at the HF region to form a plateau-like feature at all temperatures. The incremental behavior of M′ (ω) with frequency might be due to the long-range mobilities of charge carriers taking part in the conduction mechanism . We note that the frequency at which the M′ (ω) starts increasing with ω keeps shifting toward the higher frequency value with an increase in temperature.…”