The Influence of Sorbitol Doping on Aggregation and Electronic Properties of PEDOT:PSS: A Theoretical Study

Many organic electronics applications such as organic solar cells or thermoelectric generators rely on PEDOT:PSS as a conductive polymer that is printable and transparent. It was found that doping PEDOT:PSS with sorbitol enhances the conductivity through morphological changes. However, the microscopic mechanism is not well understood. In this work, we combine computational tools with machine learning to investigate changes in morphological and electronic properties of PEDOT:PSS when doped with sorbitol. We find that sorbitol improves the alignment of PEDOT oligomers, leading to a reduction of energy disorder and an increase in electronic couplings between PEDOT chains. The high accuracy (r2 > 0.9) and speed up of energy level predictions of neural networks compared to density functional theory enables us to analyze HOMO energies of PEDOT oligomers as a function of time. We find a surprisingly low degree of static energy disorder compared to other organic semiconductors. This finding might help to better understand the microscopic origin of the high charge carrier mobility of PEDOT:PSS in general and potentially help to design new conductive polymers.

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Charge carrier mobility dynamics in organic semiconductors and solar cells

Lithuanian Journal of Physics ◽

10.3952/physics.v60i1.4160 ◽

2020 ◽

Vol 60 (1) ◽

Author(s):

Vidmantas Gulbinas

Keyword(s):

Solar Cells ◽

Charge Carrier ◽

Organic Semiconductors ◽

Organic Solar Cells ◽

Carrier Mobility ◽

Charge Carrier Mobility ◽

Charge Carriers ◽

Organic Layer ◽

Stoichiometric Ratio ◽

Donor And Acceptor

Charge carrier mobility in organic semiconductors is not a constant value unambigously characterizing some particular material, but depends on the electric field, temperature and even on time after it was generated or injected. The time dependence is particularly important for the thin-film devices where charge carriers pass the organic layer before mobility reaching its stationary value. Here we give a review of experimental techniques with ultrafast timeresolution enabling one to address the mobility kinetics and analyse properties of the time-dependent mobility in conjugated polymers and organic solar cells. We analyse kinetics during the charge carrier generation and extraction of free charge carriers. The mobility typically decreases by several orders of magnitude on a picosecond-nanosecond time scale; however, its kinetics also depends on the investigation technique. The mobility kinetics in blends for bulk heterojunction solar cells strongly depends on the stoichiometric ratio of donor and acceptor materials.

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Characterization of the structural, mechanical, and electronic properties of fullerene mixtures: a molecular simulations description

Journal of Materials Chemistry C ◽

10.1039/c7tc03820h ◽

2018 ◽

Vol 6 (14) ◽

pp. 3642-3650 ◽

Cited By ~ 4

Author(s):

Naga Rajesh Tummala ◽

Saadullah G. Aziz ◽

Veaceslav Coropceanu ◽

Jean-Luc Bredas

Keyword(s):

Molecular Dynamics ◽

Density Functional Theory ◽

Solar Cells ◽

Electronic Properties ◽

Organic Solar Cells ◽

Density Functional ◽

Molecular Simulations ◽

Functional Theory ◽

Fullerene Derivatives

We investigate mixtures of fullerenes and fullerene derivatives, the most commonly used electron accepting materials in organic solar cells, by using a combination of molecular dynamics and density functional theory methods.

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Theoretical investigations of charge carrier transport in organic semiconductors of naphthalene bisimides N-substituted with alkoxyphenyl groups

Canadian Journal of Chemistry ◽

10.1139/cjc-2014-0569 ◽

2015 ◽

Vol 93 (7) ◽

pp. 740-748 ◽

Cited By ~ 6

Author(s):

Jun Yin ◽

Kadali Chaitanya ◽

Xue-Hai Ju

Keyword(s):

Density Functional Theory ◽

Charge Carrier ◽

Organic Semiconductors ◽

Carrier Mobility ◽

Density Functional ◽

Reorganization Energy ◽

Charge Carrier Mobility ◽

Transport Processes ◽

Functional Theory ◽

Transfer Integral

Three novel alkoxyphenyl N-substituted naphthalene bisimide derivatives, N,N′-bis(4-n-butoxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI1), N,N′-bis(4-n-hexyloxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI2), and N,N′-bis(4-n-octyloxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI3) as potential organic semiconductors, have been investigated using density functional theory calculations coupled with the incoherent charge-hopping model at the molecular and crystal levels. The calculated results demonstrate that the low-lying and delocalized LUMOs and larger adiabatic electron affinities of these compounds are beneficial to their stability when acting as n-type organic semiconductors. The reorganization energy and transfer integral can significantly influence the charge carrier mobility. The compounds featured with the small reorganization energy and large transfer integral have relatively high charge mobilities. The electron coupling among the dominant hopping pathways indicates that the charge-transport processes happen in the parallel dimer of neighboring molecules with π–π interaction. The investigation of the angle dependence of charge carrier mobility showed that both NBI1 and NBI3 crystals exhibit remarkable anisotropic charge transporting behaviors. The calculated absorption spectra by the time-dependent density functional theory revealed that the strongest absorption peaks in the visible region are assigned to the π → π* transition and these peaks are regulated by the transitions of HOMO → LUMO. The calculated electron mobilities of NBI1, NBI2, and NBI3 are 0.0365, 0.0312, and 0.0801 cm2 V–1 s–1, respectively, indicating that these compounds are suitable for n-type organic semiconductors.

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Synergistic Effects of Processing Additives and Thermal Annealing on Nanomorphology and Hole Mobility of Poly(3-hexylthiophene) Thin Films

Polymers ◽

10.3390/polym11010112 ◽

2019 ◽

Vol 11 (1) ◽

pp. 112 ◽

Cited By ~ 8

Author(s):

Min Park ◽

Felix Kim

Keyword(s):

Charge Carrier ◽

Thermal Annealing ◽

Organic Solar Cells ◽

Carrier Mobility ◽

Morphological Changes ◽

Synergistic Effects ◽

Diphenyl Ether ◽

Hole Mobility ◽

Charge Carrier Mobility ◽

Molecular Ordering

Control of the nanoscale molecular ordering and charge-carrier mobility of poly(3-hexylthiophene-2,5-diyl) (P3HT) was achieved by the combined use of processing additives and thermal annealing. Evaluation of four processing additives (1,8-octanedithiol (ODT), diphenyl ether (DPE), 1-chloronaphthalene (CN), and 1,8-diiodooctane (DIO), which are commonly used for the fabrication of organic solar cells, revealed that the nanoscale molecular ordering and, therefore, the charge-carrier mobility, are largely affected by the additives, as demonstrated by spectral absorption, X-ray diffraction, and atomic force microscopy. Thermal annealing selectively influenced the morphological changes, depending on the solubility of P3HT in the additive at high temperature. In the case of CN, in which P3HT can be dissolved at moderate temperature, significant molecular ordering was observed even without thermal annealing. For DIO, in which P3HT is only soluble at elevated temperature, the mobility reached 1.14 × 10−1 cm2 V−1 s−1 only after annealing. ODT and DPE were not effective as processing additives in a single-component P3HT. This study provides insight for designing the processing conditions to control the morphology and charge-transport properties of polymers.

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Design and Synthesis of Two-Dimensional Covalent Organic Frameworks with Four-Arm Cores: Prediction of Remarkable Ambipolar Charge-Transport Properties

10.26434/chemrxiv.7766786.v2 ◽

2019 ◽

Author(s):

Simil Thomas ◽

Hong Li ◽

Raghunath R. Dasari ◽

Austin Evans ◽

William Dichtel ◽

...

Keyword(s):

Charge Transport ◽

Organic Semiconductors ◽

Density Functional ◽

Polymer Networks ◽

Two Dimensional ◽

Covalent Organic Frameworks ◽

X Ray Diffraction ◽

Zinc Porphyrin ◽

Design And Synthesis ◽

Predicted Values

We have considered three two-dimensional (2D) π-conjugated polymer networks (i.e., covalent organic frameworks, COFs) materials based on pyrene, porphyrin, and zinc-porphyrin cores connected via diacetylenic linkers. Their electronic structures, investigated at the density functional theory global-hybrid level, are indicative of valence and conduction bands that have large widths, ranging between 1 and 2 eV. Using a molecular approach to derive the electronic couplings between adjacent core units and the electron-vibration couplings, the three π-conjugated 2D COFs are predicted to have ambipolar charge-transport characteristics with electron and hole mobilities in the range of 65-95 cm2V-1s-1. Such predicted values rank these 2D COFs among the highest-mobility organic semiconductors. In addition, we have synthesized the zinc-porphyrin based 2D COF and carried out structural characterization via powder X-ray diffraction and surface area analysis, which demonstrates the feasability of these electroactive networks.

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Predicted structures and electronic properties of gallium-indium clusters GamInn–m (n = 4, 6, 8 and m < n): A density functional study

Журнал структурной химии ◽

10.26902/jsc20180501 ◽

2018 ◽

Vol 59 (5) ◽

Keyword(s):

Electronic Properties ◽

Density Functional ◽

Functional Study ◽

Density Functional Study

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Defect Processes in Halogen Doped SnO2

Applied Sciences ◽

10.3390/app11020551 ◽

2021 ◽

Vol 11 (2) ◽

pp. 551

Author(s):

Petros-Panagis Filippatos ◽

Nikolaos Kelaidis ◽

Maria Vasilopoulou ◽

Dimitris Davazoglou ◽

Alexander Chroneos

Keyword(s):

Electronic Properties ◽

Tin Oxide ◽

Density Functional ◽

Structural Changes ◽

High Dielectric Constant ◽

Density Functional Theory Calculations ◽

Functional Theory ◽

Optical And Electronic Properties ◽

High Dielectric ◽

Gap States

In the present study, we performed density functional theory calculations (DFT) to investigate structural changes and their impact on the electronic properties in halogen (F, Cl, Br, and I) doped tin oxide (SnO2). We performed calculations for atoms intercalated either at interstitial or substitutional positions and then calculated the electronic structure and the optical properties of the doped SnO2. In all cases, a reduction in the bandgap value was evident, while gap states were also formed. Furthermore, when we insert these dopants in interstitial and substitutional positions, they all constitute a single acceptor and donor, respectively. This can also be seen in the density of states through the formation of gap states just above the valence band or below the conduction band, respectively. These gap states may contribute to significant changes in the optical and electronic properties of SnO2, thus affecting the metal oxide’s suitability for photovoltaics and photocatalytic devices. In particular, we found that iodine (I) doping of SnO2 induces a high dielectric constant while also reducing the oxide’s bandgap, making it more efficient for light-harvesting applications.

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