Dielectric relaxation and Ac conductivity of perovskites CH₃NH₃PbX₃ (X = Br, I)

Discerning the Role of an A-Site Cation and X-Site Anion for Ion Conductivity Tuning in Hybrid Perovskites by Photoelectrochemical Impedance Spectroscopy

“…There have been many attempts to explain the σ versus frequency feature in hybrid and inorganic perovskite heterostructures. The hopping of ions and JRM are the widely analyzed phenomena for elucidating this behavior of conductivity. ,, In CH 3 NH 3 PbX 3 (X = I and Br), conductivity increases with an increase in frequency with promotion of active polaron hopping . Garcia-Barriocanal et al suggest that the colossal ionic conductivity at the interface of epitaxial ZrO 2 /Y 2 O 3 /SrTiO 3 heterostructures is the concomitant result of reduced activation energy barrier because of uncorrelated ion diffusion along the oxygen depleted/disordered interfacial plane .…”

“…There are many reports on inspection of the electronic conductivity. − However, the ionic conductivity of the HOIP materials is still unexplored. Few researchers have attempted to elucidate the ionic conductivity spectrum using IS widely. − Various theories have been proposed to explain temperature-dependent conductivity behavior of HOIP materials, via hopping models for solid-state perovskite devices. − However, accurate understanding is not possible in these geometries because of the influence of conduction properties of transport layers in PSCs, perovskite LEDs, and other solid-state device architectures. Therefore, investigation of independent conduction properties of HOIP materials using the PEIS technique is substantial.…”

“…70,72,73 In CH 3 NH 3 PbX 3 (X = I and Br), conductivity increases with an increase in frequency with promotion of active polaron hopping. 70 Garcia-Barriocanal et al suggest that the colossal ionic conductivity at the interface of epitaxial ZrO 2 /Y 2 O 3 /SrTiO 3 heterostructures is the concomitant result of reduced activation energy barrier because of uncorrelated ion diffusion along the oxygen depleted/disordered interfacial plane. 72 In most of the solidstate HOIP devices, nearly frequency-independent (flat) conductivity behavior is seen at lower frequencies.…”

Dielectric Behavior of Mechano-chemically Synthesized [(CH3NH3)3Bi2Br9]: A Lead Free Hybrid Perovskite

“…Here, one depressed semicircular arc has appeared with center below the real axis which implies relaxation process follow non-Debye type relaxation and it may be due to the bulk effect. 21 The single semicircle appreciates overall contribution of grain and grain boundary to the With increase in temperature, layer width becomes quite small as a result cgb becomes very small. Indeed, due to the fact grain boundary capacitance decreases with increase in temperature proportional to the ratio of trapped charge carriers to free carrier density.…”

“…Here, one depressed semicircular arc has appeared with center below the real axis which implies relaxation process follow non-Debye type relaxation and it may be due to the bulk effect. 21 The single semicircle appreciates overall contribution of grain and grain boundary to the capacitive and resistive part of complex impedance also. It is evident from the figure that radius of these semicircular arc decreases with the increase of temperature.…”