First-principles prediction of charge mobility in carbon and organic nanomaterials

Abstract

We summarize our recent progresses in developing first-principles methods for predicting the intrinsic charge mobility in carbon and organic nanomaterials, within the framework of Boltzmann transport theory and relaxation time approximation. The electron-phonon couplings are described by Bardeen and Shockley's deformation potential theory, namely delocalized electrons scattered by longitudinal acoustic phonons as modeled by uniform lattice dilation. We have applied such methodology to calculating the charge carrier mobilities of graphene and graphdiyne, both sheets and nanoribbons, as well as closely packed organic crystals. The intrinsic charge carrier mobilities for graphene sheet and naphthalene are calculated to be 3 × 10(5) and ∼60 cm(2) V(-1) s(-1) respectively at room temperature, in reasonable agreement with previous studies. We also present some new theoretical results for the recently discovered organic electronic materials, diacene-fused thienothiophenes, for which the charge carrier mobilities are predicted to be around 100 cm(2) V(-1) s(-1).

A theoretical investigation on the transport properties of armchair biphenylene nanoribbons

“…The deformation potential theory has been successfully applied to similar one-dimensional structures, such as graphene nanoribbons [27,28].…”

Intrinsic Charge Transport in Stanene: Roles of Bucklings and Electron–Phonon Couplings

“…The intrinsic room-temperature mobility of stanene (2-3 × 10 3 cm 2 V −1 s −1 ) is two orders of magnitude lower that of graphene (2 × 10 5 cm 2 V −1 s −1 ). [21,24,25] It is noted that the intrinsic mobility of stanene is smaller compared to graphene, although the weaker el-ph couplings in stanene favor high carrier mobility. However, this is not obscure because the phonon frequency of stanene is one order of magnitude lower than that of graphene.…”

“…However, by implementing the Wannier-Fourier interpolation scheme, accurate electronic energies, phonon frequencies, and el-ph coupling matrix elements can be obtained with reasonable computational burden. Within this scheme, the electronic Hamiltonian [30] 2800 [38] D 3d ZA, TA [38] Silicene 2 × 10 5 [29] 2100, [36] 1200, [37] 750 [38] D 3d ZA, [36,38] TA [38] Graphene (2-3) × 10 5 , 3 × 10 5 , [24] 1 × 10 5 [27] (2-3) × 10 5 , 2 × 10 5 , [25] 1.5 × 10 5 [36] D 6h LA [25] α-Graphyne 3 × 10 4 [31] 1.6 × 10 4 [25] D 2h LA [25] Monolayer MoS 2 72-200 [32] 400, [36] 130, [37] 410, [50] 150, [52] 230 [51] D 3h LA, [37,50] LO 2 [50] Figure 5. The classification of nonplanarity for a) stanene and b) monolayer MoS 2 .…”

“…For evaluating the intrinsic carrier mobility of 2D materials, Long et al [21,22] have first applied the deformation potential approximation (DPA) proposed by Shockley and Bardeen [23] as a first-principles method, where only the scattering by longitudinal acoustic (LA) phonons are taken into account. This approach is conceptually simple but has been extremely successful as has been widely applied in calculating the intrinsic carrier mobility of 2D sheets or nanoribbons, such as graphene, [24][25][26][27][28] silicene, [29] germanene, [30] graphdiyne, [22,24] α-graphyne, [31] transition metal dichalcogenide (TMD), [32] phosphorene, [33,34] as well as perovskites. [35] DPA can overestimate the intrinsic room-temperature mobility because it only considers the longitudinal acoustic phonon scattering process.…”

Determination of crystal orientation in organic thin films using optical microscopy

“…The thermal expansion coefficient is inversely proportional to the Young's modulus [29]. The Young's modulus of C 8 -BTBT is larger along the axis a rather than b [30], which results in thermal expansion coefficient being smaller along the axis a rather than b. Therefore, cracking is most likely to occur along the plane (010).…”