Host dependence of the electron affinity of molecular dopants

Li, Jing; Duchemin, Ivan; Roscioni, Otello Maria; Friederich, Pascal; Anderson, Marie L.; Como, Enrico Da; Kociok‐Köhn, Gabriele; Wenzel, Wolfgang; Zannoni, Claudio; Beljonne, David; Blase, Xavier; D’Avino, Gabriele

doi:10.1039/c8mh00921j

Cited by 69 publications

(109 citation statements)

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“…Due to this strong dependence, small errors in the calculation of the energy disorder lead to large errors in the predicted charge carrier mobility, demanding high accuracy of all models involved in the simulation workflow. [112] Combining such approaches with accurate embedding schemes, it becomes possible to calculate solid state properties, such as thin film ionization energies or electron affinities [17,104,113] energy disorder parameters for electrons, holes, or excited states of a pristine material or a mixture of materials, distributions of electronic couplings for charge or exciton transport [114a] and optical film properties such as absorption spectra. [110,111] Recent advances toward quantitative electronic structure methods were made using methods like GW [104] or self-consistently tuned range-separated functionals.…”

Section: Electronic Structure and Quantum Embedding Methodsmentioning

confidence: 99%

“…There are other materials related issues, such as limited OLED life times due to unstable blue hosts and emitters, [9] low fill factors, and therefore reduced power conversion efficiencies of organic solar cells, [10,11] low conductivity and high costs of organic charge transport layers of perovskite solar cells [6,12,13] and low conductivity and hard processability of crystalline OFET materials. [16] The doping mechanism of organic materials is in many cases not well understood, [17] making material and device optimization a costly experimental endeavor.The development of better materials is presently based on chemical insight, in part guided by theoretical understanding, or the experimental screening of large numbers of compounds. [16] The doping mechanism of organic materials is in many cases not well understood, [17] making material and device optimization a costly experimental endeavor.…”

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Toward Design of Novel Materials for Organic Electronics

et al. 2019

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organic/inorganic perovskites solar cells [6] to printable electronic circuits based on organic field-effect transistors (OFETs). [7] While OLED displays outperform their inorganic counterparts in terms of energy efficiency, [8] scientific and technical challenges concerning the stability and processability of the organic materials used in large-area OLEDs and organic solar cells remain. New challenges arise from applications, such as displays on flexible substrates, OLED lightning, large area displays as well as for printable or solution processable larger area solar cells. [8] Many of the remaining challenges are material related, e.g., the low mobility of charge carriers in organic materials in general and in amorphous organic semiconductors in particular. There are other materials related issues, such as limited OLED life times due to unstable blue hosts and emitters, [9] low fill factors, and therefore reduced power conversion efficiencies of organic solar cells, [10,11] low conductivity and high costs of organic charge transport layers of perovskite solar cells [6,12,13] and low conductivity and hard processability of crystalline OFET materials. [14] Conductivity and injection can be improved by doping the organic thin films with molecular dopants with high electron affinities (p-type) [15] or low ionization energies (n-type). [16] The doping mechanism of organic materials is in many cases not well understood, [17] making material and device optimization a costly experimental endeavor.The development of better materials is presently based on chemical insight, in part guided by theoretical understanding, or the experimental screening of large numbers of compounds. Given the size of the potentially available chemical space this remains a costly and time-consuming approach. Recent successes in experimental design of novel materials and concepts include the development of a stable strong molecular n-type dopant, [16] a study about the quantitative relation between interaction parameter, miscibility, and function of conjugated polymer donors and small-molecule acceptors for bulk heterojunctions as used in organic solar cells [18] the development of a universal strategy for ohmic hole injection into organic semiconductors with high ionization energies [19] and many others. [20][21][22][23][24][25] Another example is the development of strategies to harvest triplet excitons in organic light emitting diodes. For this purpose, novel classes of emitter molecules were developed, which include thermally activated delayed fluorescence (TADF)-based molecules, [26][27][28][29][30][31][32] rotationally accessed spin-state inversion, [33] and radical-based emitters. [34] Materials for organic electronics are presently used in prominent applications, such as displays in mobile devices, while being intensely researched for other purposes, such as organic photovoltaics, large-area devices, and thin-film transistors. Many of the challenges to improve and optimize these applications are material related and there is a nearly inf...

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Section: Electronic Structure and Quantum Embedding Methodsmentioning

confidence: 99%

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confidence: 99%

Toward Design of Novel Materials for Organic Electronics

et al. 2019

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“…Although many p‐ and n‐type dopants are available across a large structural diversity, there is a lack of p‐type dopants with EA ≈ 5.2–6.0 eV and n‐type dopants with IP ≈ 2.8–3.6 eV . However, D'Avino and co‐workers have recently theoretically demonstrated that the EA of dopants strongly depends on molecular host as a result of electrostatic interactions, disproving the common belief that EA is an intrinsic property of pure dopants …”

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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“…[ 50 ] Its HOMO energy level was measured by CV in the same conditions than P(FBDOPV‐F) (Figure S18a, Supporting Information). Assuming limited intermolecular electrostatic interactions, [ 51 ] the energy barrier between the HOMO level of N‐DMBI (≈–4.4 eV) and the LUMO level of the polymers (>–4.1 eV) should hinder direct electron transfer (Figure S18b, Supporting Information). Upon thermal excitation, the labile hydrogen atom bonded to the sp 3 carbon of N‐DMBI (Figure S1, Supporting Information) can undergo H‐bond homolysis or H‐bond heterolysis, thus enabling molecular doping via, respectively, SOMO‐mediated electron transfer (Figure S18b, Supporting Information) or hydride transfer.…”

Section: Resultsmentioning

confidence: 99%

Impact of Morphology on Charge Carrier Transport and Thermoelectric Properties of N‐Type FBDOPV‐Based Polymers

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Kubik

Marszałek

et al. 2020

Adv Funct Materials

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The impact of the chemical structure and molecular order on the charge transport properties of two donor-acceptor copolymers in their neutral and doped states is investigated. Both polymers comprise 3,7-bis((E)-7-fluoro-1-(2-octyl-dodecyl)-2-oxoindolin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′] difuran-2,6-dione (FBDOPV) as electron-accepting unit, copolymerized with 9,9-dioctyl-fluorene (P(FBDOPV-F)) or with 3-dodecyl-2,2′-bithiophene (P(FBDOPV-2T-C 12 )). These copolymers possess an amorphous and semicrystalline nature, respectively, and exhibit remarkable electron mobilities of 0.065 and 0.25 cm 2 V -1 s -1 in field effect transistors. However, after chemical n-doping with 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl) dimethylamine (N-DMBI), electrical conductivities four orders of magnitude higher can be achieved for P(FBDOPV-2T-C 12 ) (σ = 0.042 S cm −1 ). More charge-transfer complexes are formed between P(FBDOPV-F) and N-DMBI, but the highly localized polaronic states poorly contribute to the charge transport. Doped P(FBDOPV-2T-C 12 ) exhibits a negative Seebeck coefficient of -265 µV K −1 and a thermoelectric power factor (PF) of 0.30 µW m −1 K −2 at 303 K which increases to 0.72 µW m −1 K −2 at 388 K. The in-plane thermal conductivity (κ || = 0.53 W m −1 K −1 ) on the same micrometer-thick solution-processed film is measured, resulting in a figure of merit (ZT) of 5.0 × 10 −4 at 388 K. The results provide important design guidelines to improve the doping efficiency and thermoelectric properties of n-type organic semiconductors.

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Host dependence of the electron affinity of molecular dopants

Abstract: Accurate molecular modeling reveal the surprisingly large impact of the solid-state environment on the electron acceptor levels of molecular dopants.

Cited by 69 publications

References 77 publications

Toward Design of Novel Materials for Organic Electronics

Toward Design of Novel Materials for Organic Electronics

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

Impact of Morphology on Charge Carrier Transport and Thermoelectric Properties of N‐Type FBDOPV‐Based Polymers

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