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Wang Z, Xie X, Ma H. Simultaneous Intra- and Intermolecular Singlet Fission in Bipentacene Macrocycle Aggregates. J Phys Chem Lett 2024; 15:3523-3530. [PMID: 38522085 DOI: 10.1021/acs.jpclett.4c00300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
Singlet fission (SF) is a process where a singlet state splits into two triplet states, which is essential for enhancing optoelectronic devices. Macrocyclic structures allow for precise control of chromophore orientation and facilitate singlet fission in solutions. However, the behavior of these structures in thin films, crucial for solid-state device optimization, remains underexplored. This study examines the aggregation and singlet fission processes of bipentacene macrocycles (BPc) in thin films using molecular dynamics simulations and electronic structure calculations. Findings indicate that BPc aggregates more rapidly with less chloroform, aligning parallel to the substrate. Intramolecular singlet fission (iSF) rates are rarely changed during evaporation, but the efficiency of intermolecular singlet fission (xSF) improves due to the increase in packing domains, suggesting that orderly crystal domains are not necessary for device efficiency. This opens avenues for varied device designs and traditional solution-based methods for optimal device development.
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Affiliation(s)
- Zhangxia Wang
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, China
| | - Xiaoyu Xie
- Qingdao Institute for Theoretical and Computational Sciences, School of Chemistry and Chemical Engineering, Shandong University, Qingdao, Shandong 266237, China
| | - Haibo Ma
- Qingdao Institute for Theoretical and Computational Sciences, School of Chemistry and Chemical Engineering, Shandong University, Qingdao, Shandong 266237, China
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2
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Packman L, Philippa B, Pivrikas A, Burn PL, Gentle IR. Reconstructing the 3D Coordinates of Guest:Host OLED Blends with Single Atom Resolution. SMALL METHODS 2024:e2301305. [PMID: 38517254 DOI: 10.1002/smtd.202301305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 03/08/2024] [Indexed: 03/23/2024]
Abstract
The performance of electronic and semiconductor devices is critically dependent on the distribution of guest molecules or atoms in a host matrix. One prominent example is that of organic light-emitting diode (OLED) displays containing phosphorescent emitters, now ubiquitous in handheld devices and high-end televisions. In such OLEDs the phosphorescent guest [normally an iridium(III)-based complex] is typically blended into a host matrix, and charge injection and transport, exciton formation and decay, and hence overall device performance are governed by the distribution of the emissive guest in the host. Here high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) is used with depth sectioning to reconstruct the 3D distribution of emissive iridium(III) complexes, fac-tris(2-phenylpyridine)iridium(III) [Ir(ppy)3], blended into the amorphous host material, tris(4-carbazoyl-9-ylphenyl)amine (TCTA), by resolving the position of each single iridium(III) ion. It is found that most Ir(ppy)3 complexes are clustered with at least one other, even at low concentrations, and that for films of 20 wt.% Ir(ppy)3 essentially all the complexes are interconnected. The results validate the morphology of blend films created using molecular dynamics simulations which mimic the evaporation film-forming process and are also consistent with the experimentally measured charge transport and photophysical properties.
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Affiliation(s)
- Lachlan Packman
- Centre for Organic Photonics & Electronics (COPE), School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Bronson Philippa
- College of Science & Engineering, James Cook University, Townsville, QLD, 4814, Australia
| | - Almantas Pivrikas
- Physics Department, Murdoch University, Perth, Western Australia, 6150, Australia
| | - Paul L Burn
- Centre for Organic Photonics & Electronics (COPE), School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Ian R Gentle
- Centre for Organic Photonics & Electronics (COPE), School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia
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3
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de Bruijn R, Michels JJ, van der Schoot P. Transient nucleation driven by solvent evaporation. J Chem Phys 2024; 160:084505. [PMID: 38415833 DOI: 10.1063/5.0186395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 01/31/2024] [Indexed: 02/29/2024] Open
Abstract
We theoretically investigate homogeneous crystal nucleation in a solution containing a solute and a volatile solvent. The solvent evaporates from the solution, thereby continuously increasing the concentration of the solute. We view it as an idealized model for the far-out-of-equilibrium conditions present during the liquid-state manufacturing of organic electronic devices. Our model is based on classical nucleation theory, taking the solvent to be a source of the transient conditions in which the solute drops out of the solution. Other than that, the solvent is not directly involved in the nucleation process itself. We approximately solve the kinetic master equations using a combination of Laplace transforms and singular perturbation theory, providing an analytical expression for the nucleation flux. Our results predict that (i) the nucleation flux lags slightly behind a commonly used quasi-steady-state approximation. This effect is governed by two counteracting effects originating from solvent evaporation: while a faster evaporation rate results in an increasingly larger influence of the lag time on the nucleation flux, this lag time itself is found to decrease with increasing evaporation rate. Moreover, we find that (ii) the nucleation flux and the quasi-steady-state nucleation flux are never identical, except trivially in the stationary limit, and (iii) the initial induction period of the nucleation flux, which we characterize as a generalized induction time, decreases weakly with the evaporation rate. This indicates that the relevant time scale for nucleation also decreases with an increasing evaporation rate. Our analytical theory compares favorably with results from a numerical evaluation of the governing kinetic equations.
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Affiliation(s)
- René de Bruijn
- Department of Applied Physics and Science Education, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Jasper J Michels
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Paul van der Schoot
- Department of Applied Physics and Science Education, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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4
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Lin TJ. The Influence of Large Pendent Groups on Chain Anisotropy and Electrical Energy Loss of Polyimides at High Frequency through All-Atomic Molecular Simulation. Chemphyschem 2023:e202300479. [PMID: 37802978 DOI: 10.1002/cphc.202300479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 10/06/2023] [Accepted: 10/06/2023] [Indexed: 10/08/2023]
Abstract
Polyimide is a potential material for high-performance printed circuit boards because of its chemical stability and excellent thermal and mechanical properties. Flexible printed circuit boards must have a low static dielectric constant and dielectric loss to reduce signal loss in high-speed communication devices. Engineering the molecular structure of polyimides with large pendant groups is a strategy to reduce their dielectric constant. However, there is no systematic study on how the large pendant groups influence electrical energy loss. We integrated all-atomic molecular dynamics and semi-empirical quantum mechanical calculations to examine the influence of pendant groups on polymer chain anisotropy and electrical energy loss at high frequencies. We analyzed the radius of gyration, relative shape anisotropy, dipole moment, and degree of polarization of the selected polyimides (TPAHF, TmBPHF, TpBPHF, MPDA, TriPMPDA, m-PDA, and m-TFPDA). The simulation results show that anisotropy perpendicular to chain direction and local chain rigidity correlate to electrical energy loss rather than dipole moment magnitudes. Polyimides with anisotropic pendant groups and significant local chain rigidity reduce electrical energy loss. The degree of polarization correlated well with the dielectric loss with a moderate computational cost, and difficulties in directly calculating the dielectric loss were circumvented.
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Affiliation(s)
- Tzu-Jen Lin
- Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei City, Taiwan
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5
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Bhat V, Callaway CP, Risko C. Computational Approaches for Organic Semiconductors: From Chemical and Physical Understanding to Predicting New Materials. Chem Rev 2023. [PMID: 37141497 DOI: 10.1021/acs.chemrev.2c00704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
While a complete understanding of organic semiconductor (OSC) design principles remains elusive, computational methods─ranging from techniques based in classical and quantum mechanics to more recent data-enabled models─can complement experimental observations and provide deep physicochemical insights into OSC structure-processing-property relationships, offering new capabilities for in silico OSC discovery and design. In this Review, we trace the evolution of these computational methods and their application to OSCs, beginning with early quantum-chemical methods to investigate resonance in benzene and building to recent machine-learning (ML) techniques and their application to ever more sophisticated OSC scientific and engineering challenges. Along the way, we highlight the limitations of the methods and how sophisticated physical and mathematical frameworks have been created to overcome those limitations. We illustrate applications of these methods to a range of specific challenges in OSCs derived from π-conjugated polymers and molecules, including predicting charge-carrier transport, modeling chain conformations and bulk morphology, estimating thermomechanical properties, and describing phonons and thermal transport, to name a few. Through these examples, we demonstrate how advances in computational methods accelerate the deployment of OSCsin wide-ranging technologies, such as organic photovoltaics (OPVs), organic light-emitting diodes (OLEDs), organic thermoelectrics, organic batteries, and organic (bio)sensors. We conclude by providing an outlook for the future development of computational techniques to discover and assess the properties of high-performing OSCs with greater accuracy.
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Affiliation(s)
- Vinayak Bhat
- Department of Chemistry & Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - Connor P Callaway
- Department of Chemistry & Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - Chad Risko
- Department of Chemistry & Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40506-0055, United States
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Stroet M, Sanderson S, Sanzogni AV, Nada S, Lee T, Caron B, Mark AE, Burn PL. PyThinFilm: Automated Molecular Dynamics Simulation Protocols for the Generation of Thin Film Morphologies. J Chem Inf Model 2023; 63:2-8. [PMID: 36539938 DOI: 10.1021/acs.jcim.2c01334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The performance of organic optoelectronic devices, such as organic light-emitting diodes (OLEDs) and organic solar cells (OSCs), is intrinsically related to the molecular-scale morphology of the thin films from which they are composed. However, the experimental characterization of morphology at the molecular level is challenging due to the often amorphous or at best semicrystalline nature of these films. Classical molecular modeling techniques, such as molecular dynamics (MD) simulation, are increasingly used to understand the relationship between morphology and the properties of thin-film devices. PyThinFilm (github.com/ATB-UQ/PyThinFilm) is an open-source Python package which allows fully automated MD simulations of thin film growth to be performed using vacuum and/or solution deposition processes. PyThinFilm utilizes the GROMACS simulation package in combination with interaction parameters from the Automated Topology Builder (atb.uq.edu.au). Here, PyThinFilm is described along with an overview of applications in which PyThinFilm has been used to study the thin films of organic semiconductor materials typically used in OLEDs and OSCs.
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Affiliation(s)
- Martin Stroet
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia.,Molecular Dynamics Group, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia
| | - Stephen Sanderson
- The Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia.,College of Science and Engineering, James Cook University, Townsville, Queensland4811, Australia
| | - Audrey V Sanzogni
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia.,Molecular Dynamics Group, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia
| | - Sharif Nada
- Molecular Dynamics Group, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia
| | - Thomas Lee
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia.,Molecular Dynamics Group, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia
| | - Bertrand Caron
- Molecular Dynamics Group, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia
| | - Alan E Mark
- Molecular Dynamics Group, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia
| | - Paul L Burn
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia Campus, Brisbane, Queensland4072, Australia
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Sanderson S, Vamvounis G, Mark AE, Burn PL, White RD, Philippa BW. Understanding the performance differences between solution and vacuum deposited OLEDs: A computational approach. J Chem Phys 2022; 156:214703. [DOI: 10.1063/5.0091142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Solution-processing of organic light-emitting diode films has potential advantages in terms of cost and scalability over vacuum-deposition for large area applications. However, solution processed small molecule films can have lower overall device performance. Here, novel molecular dynamics techniques are developed to enable faster simulation of solvent evaporation that occurs during solution processing and give films of thicknesses relevant to real devices. All-atom molecular dynamics simulations are then used in combination with kinetic Monte Carlo transport modeling to examine how differences in morphology stemming from solution or vacuum film deposition affect charge transport and exciton dynamics in films consisting of light-emitting bis(2-phenylpyridine)(acetylacetonate)iridium(III) [Ir(ppy)2(acac)] guest molecules in a 4,4′-bis( N-carbazolyl)biphenyl host. While the structures of the films deposited from vacuum and solution were found to differ, critically, only minor variations in the transport properties were predicted by the simulations even if trapped solvent was present.
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Affiliation(s)
- Stephen Sanderson
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - George Vamvounis
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Alan E. Mark
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Paul L. Burn
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ronald D. White
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Bronson W. Philippa
- College of Science and Engineering, James Cook University, Cairns, QLD 4878, Australia
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Boehm BJ, Huang DM. A simple predictor of interface orientation of fluids of disk-like anisotropic particles and its implications for organic semiconductors. SOFT MATTER 2022; 18:1843-1857. [PMID: 35169825 DOI: 10.1039/d2sm00026a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
From classical molecular dynamics simulations, we identify a simple and general predictor of molecular orientation at solid and vapour interfaces of isotropic fluids of disk-like anisotropic particles based on their shape and interaction anisotropy. For a wide variety of inter-particle interactions, temperatures, and substrate types within the range of typical organic semiconductors and their processing conditions, we find remarkable universal scaling of the orientation at the interface with the free energy calculated from pair interactions between close-packed nearest neighbours and an empirically derived universal relationship between the entropy and the shape anisotropy and bulk volume fraction of the fluid particles. The face-on orientation of fluid particles at the solid interface is generally predicted to be the equilibrium structure, although the alignment can be controlled by tuning the particle shape and substrate type, while changing the strength of fluid-fluid interactions is likely to play a less effective role. At the vapour interface, only the side-on structure is predicted, and conditions for which the face-on structure may be preferred, such as low temperature, low interaction anisotropy, or low shape anisotropy, are likely to result in little orientation preference (due to the low anisotropy) or be associated with a phase transition to an anisotropic bulk phase for systems with interactions in the range of typical organic semiconductors. Based on these results, we propose a set of guidelines for the rational design and processing of organic semiconductors to achieve a target orientation at a solid or vapour interface.
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Affiliation(s)
- Belinda J Boehm
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, Australia.
| | - David M Huang
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, Australia.
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Callaway CP, Liu AL, Venkatesh R, Zheng Y, Lee M, Meredith JC, Grover M, Risko C, Reichmanis E. The Solution is the Solution: Data-Driven Elucidation of Solution-to-Device Feature Transfer for π-Conjugated Polymer Semiconductors. ACS APPLIED MATERIALS & INTERFACES 2022; 14:3613-3620. [PMID: 35037454 DOI: 10.1021/acsami.1c20994] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The advent of data analytics techniques and materials informatics provides opportunities to accelerate the discovery and development of organic semiconductors for electronic devices. However, the development of engineering solutions is limited by the ability to control thin-film morphology in an immense parameter space. The combination of high-throughput experimentation (HTE) laboratory techniques and data analytics offers tremendous avenues to traverse the expansive domains of tunable variables offered by organic semiconductor thin films. This Perspective outlines the steps required to incorporate a comprehensive informatics methodology into the experimental development of polymer-based organic semiconductor technologies. The translation of solution processing and property metrics to thin-film behavior is crucial to inform efficient HTE for data collection and application of data-centric tools to construct new process-structure-property relationships. We argue that detailed investigation of the solution state prior to deposition in conjunction with thin-film characterization will yield a deeper understanding of the physicochemical mechanisms influencing performance in π-conjugated polymer electronics, with data-driven approaches offering predictive capabilities previously unattainable via traditional experimental means.
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Affiliation(s)
- Connor P Callaway
- Department of Chemistry & Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - Aaron L Liu
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332, United States
| | - Rahul Venkatesh
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332, United States
| | - Yulong Zheng
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, United States
| | - Myeongyeon Lee
- Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - J Carson Meredith
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332, United States
| | - Martha Grover
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332, United States
| | - Chad Risko
- Department of Chemistry & Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - Elsa Reichmanis
- Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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