Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors

He, Tao; Wu, Yanfei; D’Avino, Gabriele; Schmidt, Elliot; Stolte, Matthias; Cornil, Jérôme; Beljonne, David; Ruden, P. P.; Würthner, Frank; Frisbie, C. Daniel

doi:10.1038/s41467-018-04479-z

Cited by 64 publications

(77 citation statements)

References 46 publications

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“…This interface is free of polaronic effects and strain, but it is not exempt from the trapping resulting from imperfections at the crystal surface. Crystal step edges present on the surfaces of organic semiconductors single crystal were found to be trapping sites for the charges accumulated at the interface between the crystal and the dielectric . While we do not have a quantitative analysis of the density of the step edges in our crystals, by simple optical inspection it can be clearly seen that their density is very high.…”

Section: Resultsmentioning

confidence: 99%

Charge‐Transport Properties of F₆TNAP‐Based Charge‐Transfer Cocrystals

Dasari

Wang

Wiscons

et al. 2019

Adv Funct Materials

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The crystal structures of the charge-transfer (CT) cocrystals formed by the π-electron acceptor 1,3,4,5,7,8-hexafluoro-11,11,12,12-tetracyanonaphtho-2,6-quinodimethane (F 6 TNAP) with the planar π-electron-donor molecules triphenylene (TP), benzo[b]benzo[4,5]thieno[2,3-d]thiophene (BTBT), benzo[1,2-b:4,5-b′]dithiophene (BDT), pyrene (PY), anthracene (ANT), and carbazole (CBZ) have been determined using single-crystal X-ray diffraction (SCXRD), along with those of two polymorphs of F 6 TNAP. All six cocrystals exhibit 1:1 donor/acceptor stoichiometry and adopt mixed-stacking motifs. Cocrystals based on BTBT and CBZ π-electron donor molecules exhibit brickwork packing, while the other four CT cocrystals show herringbone-type crystal packing. Infrared spectroscopy, molecular geometries determined by SCXRD, and electronic structure calculations indicate that the extent of ground-state CT in each cocrystal is small. Density functional theory calculations predict large conduction bandwidths and, consequently, low effective masses for electrons for all six CT cocrystals, while the TP-, BDT-, and PYbased cocrystals are also predicted to have large valence bandwidths and low effective masses for holes. Charge-carrier mobility values are obtained from space-charge limited current (SCLC) measurements and field-effect transistor measurements, with values exceeding 1 cm 2 V −1 s −1 being estimated from SCLC measurements for BTBT:F 6 TNAP and CBZ:F 6 TNAP cocrystals. exhibit properties distinct from those of their individual components. In chargetransfer (CT) cocrystals, one component acts as an π-electron donor (D) and another component acts as a π-electron acceptor (A), and both are typically planar molecules in order to facilitate CT interactions in the solid state. Two major types of molecular stacking motifs are found in CT crystals with 1:1 stoichiometry: mixed stacks, in which D and A molecules alternate along the stacking direction, -D-A-D-A, and segregated stacks, in which donor and acceptor molecules form separate stacks, -D-D-D-and -A-A-A. [1][2][3] When free of disorder, metallic conductivities can be obtained along the stacking direction of CT cocrystals that form segregated stacks and that exhibit extents of CT approximately midway (ρ = ca. 0.5) between the completely neutral (ρ = 0) and fully ionic (ρ = 1) limits. [1][2][3][4] On the other hand, CT cocrystals that consist of mixed stacks generally behave as semiconductors or insulators. [3,5] Recently there has been increasing interest in the semiconducting [6][7][8][9][10][11][12][13][14][15][16][17][18] and photoconductive [19][20][21] properties of mixed-stack cocrystals. Large charge-carrier mobility values, µ, have been reported for several examples using space-charge limited current (SCLC) or field-effect transistor (FET) measurements, includingThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

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Section: Resultsmentioning

confidence: 99%

Charge‐Transport Properties of F₆TNAP‐Based Charge‐Transfer Cocrystals

Dasari

Wang

Wiscons

et al. 2019

Adv Funct Materials

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Section: Experimental Methods For Investigating Charge Trapsmentioning

confidence: 99%

“…He et al directly visualized the trap states present at structural defects (i.e., at a crystal edge) on the surface of an n‐type semiconductor by using SKPM . The authors investigated in detail the correlation between field‐effect charge transport and structural properties (the density of the crystal step edge and the crystal orientation) of a single crystal of N , N ′‐bis‐(heptafluorobutyl)‐2,6‐dichloro‐1,4,5,8‐naphthalene tetracarboxylic diimide (Cl 2 ‐NDI).…”

Section: Experimental Methods For Investigating Charge Trapsmentioning

confidence: 99%

Recent Advances in the Bias Stress Stability of Organic Transistors

Park

Kim

Choi

et al. 2019

Adv Funct Materials

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In this progress report, recent advances in the development of organic transistors with superior bias stress stability and in the understanding of the charge traps that degrade device performance under prolonged bias stress are reviewed, with a particular focus on materials science and engineering methods. The phenomenological aspects of bias stress effects and the experimental methods for investigating charge traps are described. The recent progress in the bias stress stability of organic transistors is discussed in terms of those components that are the main focus of attempts to improve bias stress stability, i.e., organic semiconductor layers, gate dielectrics, and source/drain contacts. A brief summary of this progress is presented and the outlook for future research in this field is assessed. This report aims to summarize recent progress in this field and to provide some guidelines for studying bias stress-induced charge-trapping phenomena.

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“…Tetracene surface undergoes a large structural relaxation, whereas the one of higher molecular weights rubrene 3 does not . Frisbie et al have recently reported that crystal step edges trap electrons on the surfaces of F2‐TCNQ 19 , Cl 2 ‐NDI 20 , and PDIF‐CN 2 21 . High‐resolution scanning Kelvin probe microscopy images combined with charge transport measurements show that the magnitude of the step edge potential is correlated with the sensitivity of µ to the number of step edges.…”

Section: Charge Transportmentioning

confidence: 99%

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

et al. 2020

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The field of organic electronics has been prolific in the last couple of years, leading to the design and synthesis of several molecular semiconductors presenting a mobility in excess of 10 cm2 V−1 s−1. However, it is also started to recently falter, as a result of doubtful mobility extractions and reduced industrial interest. This critical review addresses the community of chemists and materials scientists to share with it a critical analysis of the best performing molecular semiconductors and of the inherent charge transport physics that takes place in them. The goal is to inspire chemists and materials scientists and to give them hope that the field of molecular semiconductors for logic operations is not engaged into a dead end. To the contrary, it offers plenty of research opportunities in materials chemistry.

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Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors

Cited by 64 publications

References 46 publications

Charge‐Transport Properties of F₆TNAP‐Based Charge‐Transfer Cocrystals

Charge‐Transport Properties of F₆TNAP‐Based Charge‐Transfer Cocrystals

Recent Advances in the Bias Stress Stability of Organic Transistors

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

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Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors

Cited by 64 publications

References 46 publications

Charge‐Transport Properties of F6TNAP‐Based Charge‐Transfer Cocrystals

Charge‐Transport Properties of F6TNAP‐Based Charge‐Transfer Cocrystals

Recent Advances in the Bias Stress Stability of Organic Transistors

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

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Charge‐Transport Properties of F₆TNAP‐Based Charge‐Transfer Cocrystals

Charge‐Transport Properties of F₆TNAP‐Based Charge‐Transfer Cocrystals