Hopping and band mobilities of pentacene, rubrene, and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) from first principle calculations

Abstract

Hopping and band mobilities of holes in organic semiconductors at room temperature were estimated from first principle calculations. Relaxation times of charge carriers were evaluated using the acoustic deformation potential model. It is found that van der Waals interactions play an important role in determining accurate relaxation times. The hopping mobilities of pentacene, rubrene, and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) in bulk single crystalline structures were found to be smaller than 4 cm(2)∕Vs, whereas the band mobilities were estimated between 36 and 58 cm(2)∕Vs, which are close to the maximum reported experimental values. This strongly suggests that band conductivity is dominant in these materials even at room temperature.

Small Molecule/Polymer Blend Organic Transistors with Hole Mobility Exceeding 13 cm2 V−1 s−1

“…[5] [7] [22] As the complementary polymer binder we selected the indacenodithiophene-benzothiadiazole (C16IDT-BT) [ Figure 1(a)] primarily due to its good solubility, high hole mobility (3.6 cm 2 /Vs) [23] [24] [25] and comparable highest occupied molecular orbital (HOMO) energy level to that of the C8-BTBT [ Figure 1(b)]. [26] [27] Using this unique combination of materials we have demonstrated solution-processed OTFTs with hole mobility values in excess of 13 cm 2 /Vs. Key to our success is the incorporation of a [28] [29] which acts as both a p-dopant and an electron scavenger.…”

Mobility enhancement in polymer organic semiconductors arising from increased interconnectivity at the level of polymer segments

“…Nevertheless, the values obtained in recent measurements 14,15 of mobility in small molecule single crystals are similar in magnitude to the predictions made with the 2D deformation potential model. 6,10 Of course, polymers are significantly more disordered than single crystal small molecules, so one does not expect quantitative agreement between the model and experimental mobility obtained for polymers.…”

“…[6][7][8][9][10] A 2D model is appropriate in the case that electronic coupling in the direction perpendicular to stacked lamellae is negligible. This is the case for polymers such as P3HT and PBTTT, where the lamellae are separated by electronically insulating alkyl chains.…”

“…In the two-dimensional deformation potential model, [6][7][8][9][10] the in-plane mobility is given by…”

Molecular Orbital-Based Verification of Conductivity of Tetramethylammonium Pentaiodide and Pentaiodide-Based Electrolytes in Dye-Sensitized Solar Cells

“…5,6 The high charge mobility of organic semiconductor crystals was discussed using the hoping or the band model. 7 By using the semi-classical dynamics and parameters obtained with the density functional theory (DFT) MO calculation of a single molecule or a molecular dimer, the hopping or the polaron model successfully described the high hole mobility of the organic semiconductors at room temperature. [8][9][10] One of the authors investigated the highest mobility of crystalline rubrene in view of the band dispersion, 11 and the electronic properties of methylammonium lead iodide perovskite [CH 3 NH 3 + PbI 3 − ] were discussed on the basis of effective masses of electrons and holes in the ambipolar transport.…”