Band gap, effective masses, and energy level alignment of 2D and 3D halide perovskites and heterostructures using DFT-1/2

Abstract

We revisit the Slater half-occupation technique within the DFT-1/2 method to provide improved accuracy of 2D and 3D halide perovskites band gaps at a moderate computational cost. We propose an electron removal scheme from the halide states that drastically improve the predicted band gaps of 2D compounds. Concurrently, we compute the effective masses of the considered structures and show that DFT-1/2 describes them with a nice degree of accuracy when compared to available experimental data. Moreover, we assess the suitability of DFT-1/2 to compute the energy level alignments of this family of compounds. We compare the results in light of those we predict using the hybrid functional HSE06 and the many body perturbation theory within the G0W 0 approximation. We discuss the limitations of our refined DFT-1/2 scheme, which tends to overestimate the downshift of the absolute valence energy levels of the layered perovskite systems.We anticipate that our results would be useful to initiate benchmark studies and investigate large systems such as heterostructures for which other approaches may be out of reach.

Direct Characterization of Type‐I Band Alignment in 2D Ruddlesden–Popper Perovskites

“…The reduced masses were then calculated using the electron and hole effective masses ($$\mu = \frac{{{m_e}{m_h}}}{{{m_e} + {m_h}}}$$); the results for n = 1–5 are summarized in Table 1 . We find the hole effective masses are in general slightly larger than the electron effective masses, which agrees with previous reports for 2D [ 39 ] and 3D [ 40,41 ] perovskites. The calculated reduced masses are on the order of 0.1 m 0 (where m 0 is the free electron mass), which is somewhat smaller than the experimentally derived values (0.23–0.2 for n = 1–4).…”

First-Principles Study of Electronic Properties of Cesium Chloride Double Perovskites Using a DFT-1/2 Approach

“…This behavior is consistent with previous results of DFT-1/2 effective masses for other materials . Recently, Traore et al showed that PBE functionals severely underestimate the effective masses of different halide perovskites and that DFT-1/2 provides results in better agreement with experimental data . The results in Table also confirm the relatively large carrier effective masses of double perovskites, which may be related to the low electronic dimensionality of these compounds .…”

“…28 Recently, Traore et al showed that PBE functionals severely underestimate the effective masses of different halide perovskites and that DFT-1/2 provides results in better agreement with experimental data. 54 The results in Table 4 also confirm the relatively large carrier effective masses of double perovskites, which may be related to the low electronic dimensionality of these compounds. 55 We also note that, for all compounds studied, the effective masses of holes are highly anisotropic.…”

Landé g factors in tetragonal halide perovskite: A multiband k.p model

“…Our k.p values for MAPbI 3 compare favorably to the masses obtained by Traore et al [59]. Very recently, Su et al [60] derived the carrier masses for the tetragonal phase in CsPbBr 3 .…”