Intrinsic Carrier Mobility of Cesium Lead Halide Perovskites

Abstract

Inorganic cesium-lead-halide perovskites (CsPbX 3 , where X = Cl, Br, and I) have recently emerged as promising semiconductors for photovoltaic and light-emitting devices. In this study, we investigate electronic and vibrational properties of CsPbX 3 using the density-functional-theory calculations. We explicitly evaluate k-dependent electron-phonon scattering rates of the polar longitudinal-optical phonon modes. The transport property at room temperature is then computed based on Boltzmann transport theory within the relaxation-time approximation. The computational results identify the fundamental limit of the carrier mobility and its dependence on the halide species. Our results show that different choices of X lead to the variation in the mobility by a factor of 3 to 5 depending on the carrier concentration between 10 15 and 10 18 cm −3 . The preferred carrier type (electron or hole) in terms of the mobility also varies with X . Through the detailed analysis on the band structures and scattering rates, we provide insights into the role of halide species in the transport properties.

Polarons in Metal Halide Perovskites

“…This behavior can be associated to the higher ionicity and the reduced screening of charges in bromides, when compared to iodide perovskites. We note that the larger stabilization energy calculated for Br‐containing perovskite is consistent with the trends observed from recently estimated values of carriers' mobility for CsPbX 3 (X = I, Br, Cl) …”

Impact of nonparabolic electronic band structure on the optical and transport properties of photovoltaic materials

“…1,2 Recent work has also emphasised the impact of band non-parabolicity on electron transport in semiconductors. [3][4][5] There are a number of algebraic definitions for the effective mass that can be used to calculate it from the band dispersion relation, E(k); which can be obtained, for example, from ab initio electronic structure calculations. For ideal parabolic bands, these definitions give equal effective mass values.…”

Light Generation in Lead Halide Perovskite Nanocrystals: LEDs, Color Converters, Lasers, and Other Applications

“…Another advantage offered by LHP‐NCs is natural ambipolar charge carrier transport, which is comparable to hole and electron mobilities and is essential for high energy‐efficiency in electrically driven LEDs . Apart from the intrinsic factors mentioned above, both the hole and electron mobilities of a LHP‐NC film remain at a modest level of ≈0.5 cm 2 V −1 s −1 , even with extrinsic scattering from grain boundaries, impurities, and surrounding ligands.…”

“…For an LHP‐NC LED driven by imbalanced charge carriers in the recombination zone, the excess carrier species are themselves the loss, and the resulting interaction with excitons leads to an additional loss, even at a low driving current density, via the Auger nonradiative process. The comparable mobilities of electrons and the holes of LHP‐NCs are a good feature for realizing balanced opposite charge carriers in the recombination zone . However, the field‐dependent mobility of the matched functional layers makes it difficult to balance the opposite charge at all times under a changing bias …”