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Zojer E. Electrostatically Designing Materials and Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2406178. [PMID: 39194368 DOI: 10.1002/adma.202406178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 07/08/2024] [Indexed: 08/29/2024]
Abstract
Collective electrostatic effects arise from the superposition of electrostatic potentials of periodically arranged (di)polar entities and are known to crucially impact the electronic structures of hybrid interfaces. Here, it is discussed, how they can be used outside the beaten paths of materials design for realizing systems with advanced and sometimes unprecedented properties. The versatility of the approach is demonstrated by applying electrostatic design not only to metal-organic interfaces and adsorbed (complex) monolayers, but also to inter-layer interfaces in van der Waals heterostructures, to polar metal-organic frameworks (MOFs), and to the cylindrical pores of covalent organic frameworks (COFs). The presented design ideas are straightforward to simulate and especially for metal-organic interfaces also their experimental implementation has been amply demonstrated. For van der Waals heterostructures, the needed building blocks are available, while the required assembly approaches are just being developed. Conversely, for MOFs the necessary growth techniques exist, but more work on advanced linker molecules is required. Finally, COF structures exist that contain pores decorated with polar groups, but the electrostatic impact of these groups has been largely ignored so far. All this suggest that the dawn of the age of electrostatic design is currently experienced with potential breakthroughs lying ahead.
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Affiliation(s)
- Egbert Zojer
- Institute of Solid State Physics, NAWI Graz, Petersgasse 16, Graz, A-8010, Austria
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2
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Jangid V, Brunel D, Sanchez-Adaime E, Bharwal AK, Dumur F, Duché D, Abel M, Koudia M, Buffeteau T, Nijhuis CA, Berginc G, Lebouin C, Escoubas L. Improving Orientation, Packing Density, and Molecular Arrangement in Self-Assembled Monolayers of Bianchoring Ferrocene-Triazole Derivatives by "Click" Chemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:3585-3596. [PMID: 35259297 DOI: 10.1021/acs.langmuir.2c00215] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This work describes the self-assembled monolayers (SAMs) of two ferrocene derivatives with two anchoring groups (at the bottom and at the top of the SAM) deposited on ultraflat template-stripped gold substrates by cyclic voltammetry and analyzed by complementary surface characterization techniques. The SAM of each molecule is deposited by three different protocols: direct deposition (one step), click reaction on the surface (two steps), and reverse click reaction on the surface (two steps). The SAM structure is well studied to determine the SAM orientation, SAM arrangement, and ferrocene position within the SAM. Electron transfer kinetics have also been studied, which agree with the quality of each SAM. With the help of two anchoring groups and click-chemistry active functional groups, we have shown that the two molecules can be deposited by controlling the position of ferrocene at either end. We further investigated the involvement of the triazole five-membered ring in the electron transfer mechanism. We have found that a carbon spacer between ferrocene and triazole improves the SAM packing. This study enhances the understanding of tethering thiol and thiol acetate anchoring groups on gold by a controlled orientation, which may help in the development of functional molecular devices requiring two anchoring groups.
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Affiliation(s)
- Vikas Jangid
- Aix Marseille University, CNRS, Université de Toulon, IM2NP, UMR 7334, F-13397 Marseille, France
- Aix Marseille University, CNRS, MADIREL, UMR 7246, F-13397 Marseille, France
| | - Damien Brunel
- Aix Marseille University, CNRS, ICR, UMR 7273, F-13397 Marseille, France
| | - Esteban Sanchez-Adaime
- Aix Marseille University, CNRS, Université de Toulon, IM2NP, UMR 7334, F-13397 Marseille, France
| | - Anil Kumar Bharwal
- Aix Marseille University, CNRS, Université de Toulon, IM2NP, UMR 7334, F-13397 Marseille, France
| | - Frédéric Dumur
- Aix Marseille University, CNRS, ICR, UMR 7273, F-13397 Marseille, France
| | - David Duché
- Aix Marseille University, CNRS, Université de Toulon, IM2NP, UMR 7334, F-13397 Marseille, France
| | - Mathieu Abel
- Aix Marseille University, CNRS, Université de Toulon, IM2NP, UMR 7334, F-13397 Marseille, France
| | - Mathieu Koudia
- Aix Marseille University, CNRS, Université de Toulon, IM2NP, UMR 7334, F-13397 Marseille, France
| | - Thierry Buffeteau
- Université Bordeaux, Institut des Sciences Moléculaires ISM, CNRS UMR5255, F-33405 Talence, France
| | - Christian A Nijhuis
- Hybrid Materials for Opto-Electronics Group, Department of Molecules and Materials, MESA + Institute for Nanotechnology and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, 7500 AE Enschede, The Netherlands
| | | | - Chrystelle Lebouin
- Aix Marseille University, CNRS, MADIREL, UMR 7246, F-13397 Marseille, France
| | - Ludovic Escoubas
- Aix Marseille University, CNRS, Université de Toulon, IM2NP, UMR 7334, F-13397 Marseille, France
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Sizov AS, Agina EV, Ponomarenko SA. Self-assembled interface monolayers for organic and hybrid electronics. RUSSIAN CHEMICAL REVIEWS 2019. [DOI: 10.1070/rcr4897] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Bertram M, Schuschke C, Waidhas F, Schwarz M, Hohner C, Montero MA, Brummel O, Libuda J. Molecular anchoring to oxide surfaces in ultrahigh vacuum and in aqueous electrolytes: phosphonic acids on atomically-defined cobalt oxide. Phys Chem Chem Phys 2019; 21:23364-23374. [PMID: 31637373 DOI: 10.1039/c9cp03779a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this work, we investigated the interaction of phenylphosphonic acid (PPA, C6H5PO3H2) with atomically-defined Co3O4(111) thin films, grown on Ir(100), under ultrahigh vacuum (UHV) conditions and in the electrochemical environment. In the first step, we employed infrared reflection absorption spectroscopy (IRAS) and followed the formation of a saturated monolayer (380 K) in UHV. We observed that the binding motif changes from a chelating tridentate in the sub-monolayer regime to a chelating bidentate at full monolayer coverages. In the electrochemical environment, we analyzed the interaction of PPA with the same Co3O4(111) surface by electrochemical infrared reflection absorption spectroscopy (EC-IRRAS) (0.3 VRHE-1.3 VRHE). When adsorbed at pH 10 from an ammonia buffered aqueous solution, PPA binds to the surface in form of a fully deprotonated chelating bidentate. With increasing electrode potential, we observed two fully reversible processes. At low buffer concentration, protons are released upon oxidation of surface Co2+ ions and lead to protonation of the anchored phosphonates. At high buffer concentration, most of the protons released are accepted by NH3. Simultaneously, the surface phosphonate changes its adsorption motif from bidentate to tridentate while adopting a more upright geometry.
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Affiliation(s)
- Manon Bertram
- Interface Research and Catalysis, Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen, Germany.
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5
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Sauter E, Nascimbeni G, Trefz D, Ludwigs S, Zojer E, von Wrochem F, Zharnikov M. A dithiocarbamate anchoring group as a flexible platform for interface engineering. Phys Chem Chem Phys 2019; 21:22511-22525. [PMID: 31588446 DOI: 10.1039/c9cp03306h] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The molecular organization and electronic properties of dithiocarbamate (DTC) anchored self-assembled monolayers (SAMs) linked to Au(111) substrates are studied by a combination of X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and state-of-the-art density functional theory calculations. For that, several piperidine/piperazine precursors with different architecture and substitution patterns are selected. The presented data show that the DTC anchor provides a useful building block for monomolecular self-assembly on coinage metals with both sulfur atoms bonded to the substrate in a way similar to what is usually observed for the more commonly applied thiolate docking group. The combination of the DTC group with the quite flexible piperidine/piperazine cyclic linkers results in a dense molecular packing with an upright orientation of the terminal moieties. The latter comprise phenyl rings bearing various substituents, which enables tuning the interfacial dipole over a wide range. Simulations on two prototypical DTC-docked SAMs help to better understand the experimental observations and provide insight into the local origin of the SAM-induced shifts in the electrostatic energy. In particular, a comparison of measured and simulated XP spectra reveals the significant contribution of the DTC group to the interfacial dipole.
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Affiliation(s)
- Eric Sauter
- Applied Physical Chemistry, Heidelberg University, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
| | - Giulia Nascimbeni
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
| | - Daniel Trefz
- Chair for Structure and Properties of Polymeric Materials, Institute of Polymer Chemistry (IPOC), University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Sabine Ludwigs
- Chair for Structure and Properties of Polymeric Materials, Institute of Polymer Chemistry (IPOC), University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Egbert Zojer
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
| | - Florian von Wrochem
- Institute of Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany.
| | - Michael Zharnikov
- Applied Physical Chemistry, Heidelberg University, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
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Benneckendorf FS, Hillebrandt S, Ullrich F, Rohnacher V, Hietzschold S, Jänsch D, Freudenberg J, Beck S, Mankel E, Jaegermann W, Pucci A, Bunz UHF, Müllen K. Structure-Property Relationship of Phenylene-Based Self-Assembled Monolayers for Record Low Work Function of Indium Tin Oxide. J Phys Chem Lett 2018; 9:3731-3737. [PMID: 29923411 DOI: 10.1021/acs.jpclett.8b01242] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Studying the structure-property relations of tailored dipolar phenyl and biphenylphosphonic acids, we report self-assembled monolayers with a significant decrease in the work function (WF) of indium-tin oxide (ITO) electrodes. Whereas the strengths of the dipoles are varied through the different molecular lengths and the introduction of electron-withdrawing fluorine atoms, the surface energy is kept constant through the electron-donating N, N-dimethylamine head groups. The self-assembled monolayer formation and its modification of the electrodes are investigated via infrared reflection absorption spectroscopy, contact angle measurements, and photoelectron spectroscopy. The WF decrease in ITO correlates with increasing molecular dipoles. The lowest ever recorded WF of 3.7 eV is achieved with the fluorinated biphenylphosphonic acid.
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Affiliation(s)
- Frank S Benneckendorf
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Organisch-Chemisches Institut , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 270 , 69120 Heidelberg , Germany
| | - Sabina Hillebrandt
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Kirchhoff-Institut für Physik , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 227 , 69120 Heidelberg , Germany
| | - Florian Ullrich
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Institute of Materials Science , Technische Universität Darmstadt , Petersenstraße 32 , 64287 Darmstadt , Germany
| | - Valentina Rohnacher
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Kirchhoff-Institut für Physik , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 227 , 69120 Heidelberg , Germany
| | - Sebastian Hietzschold
- Institut für Hochfrequenztechnik , Technische Universität Braunschweig , Schleinitzstr. 22 , 38106 Braunschweig , Germany
| | - Daniel Jänsch
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Organisch-Chemisches Institut , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 270 , 69120 Heidelberg , Germany
| | - Jan Freudenberg
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Organisch-Chemisches Institut , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 270 , 69120 Heidelberg , Germany
| | - Sebastian Beck
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Kirchhoff-Institut für Physik , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 227 , 69120 Heidelberg , Germany
| | - Eric Mankel
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Institute of Materials Science , Technische Universität Darmstadt , Petersenstraße 32 , 64287 Darmstadt , Germany
| | - Wolfram Jaegermann
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Institute of Materials Science , Technische Universität Darmstadt , Petersenstraße 32 , 64287 Darmstadt , Germany
| | - Annemarie Pucci
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Kirchhoff-Institut für Physik , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 227 , 69120 Heidelberg , Germany
- Centre for Advanced Materials , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 225 , 69120 Heidelberg , Germany
| | - Uwe H F Bunz
- Organisch-Chemisches Institut , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 270 , 69120 Heidelberg , Germany
- Centre for Advanced Materials , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 225 , 69120 Heidelberg , Germany
| | - Klaus Müllen
- InnovationLab , Speyerer Straße 4 , 69115 Heidelberg , Germany
- Max Planck Institute for Polymer Research , Ackermannweg 10 , 55128 Mainz , Germany
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7
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Hietzschold S, Hillebrandt S, Ullrich F, Bombsch J, Rohnacher V, Ma S, Liu W, Köhn A, Jaegermann W, Pucci A, Kowalsky W, Mankel E, Beck S, Lovrincic R. Functionalized Nickel Oxide Hole Contact Layers: Work Function versus Conductivity. ACS APPLIED MATERIALS & INTERFACES 2017; 9:39821-39829. [PMID: 29052974 DOI: 10.1021/acsami.7b12784] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nickel oxide (NiO) is a widely used material for efficient hole extraction in optoelectronic devices. However, its surface characteristics strongly depend on the processing history and exposure to adsorbates. To achieve controllability of the electronic and chemical properties of solution-processed nickel oxide (sNiO), we functionalize its surface with a self-assembled monolayer (SAM) of 4-cyanophenylphosphonic acid. A detailed analysis of infrared and photoelectron spectroscopy shows the chemisorption of the molecules with a nominal layer thickness of around one monolayer and gives an insight into the chemical composition of the SAM. Density functional theory calculations reveal the possible binding configurations. By the application of the SAM, we increase the sNiO work function by up to 0.8 eV. When incorporated in organic solar cells, the increase in work function and improved energy level alignment to the donor does not lead to a higher fill factor of these cells. Instead, we observe the formation of a transport barrier, which can be reduced by increasing the conductivity of the sNiO through doping with copper oxide. We conclude that the widespread assumption of maximizing the fill factor by only matching the work function of the oxide charge extraction layer with the energy levels in the active material is a too narrow approach. Successful implementation of interface modifiers is only possible with a sufficiently high charge carrier concentration in the oxide interlayer to support efficient charge transfer across the interface.
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Affiliation(s)
- Sebastian Hietzschold
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Institute for High-Frequency Technology, TU Braunschweig , Schleinitzstr. 22, 38106 Braunschweig, Germany
- Kirchhoff-Institute for Physics, Heidelberg University , Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Sabina Hillebrandt
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Kirchhoff-Institute for Physics, Heidelberg University , Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Florian Ullrich
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Surface Science Division, TU Darmstadt , Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany
| | - Jakob Bombsch
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Kirchhoff-Institute for Physics, Heidelberg University , Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Valentina Rohnacher
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Kirchhoff-Institute for Physics, Heidelberg University , Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Shuangying Ma
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Institute for Theoretical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Wenlan Liu
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Institute for Theoretical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Andreas Köhn
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Institute for Theoretical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Wolfram Jaegermann
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Surface Science Division, TU Darmstadt , Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany
| | - Annemarie Pucci
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Kirchhoff-Institute for Physics, Heidelberg University , Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
- Centre for Advanced Materials, Heidelberg University , Im Neuenheimer Feld, 69120 Heidelberg, Germany
| | - Wolfgang Kowalsky
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Institute for High-Frequency Technology, TU Braunschweig , Schleinitzstr. 22, 38106 Braunschweig, Germany
| | - Eric Mankel
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Surface Science Division, TU Darmstadt , Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany
| | - Sebastian Beck
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Kirchhoff-Institute for Physics, Heidelberg University , Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Robert Lovrincic
- InnovationLab , Speyerer Str. 4, 69115 Heidelberg, Germany
- Institute for High-Frequency Technology, TU Braunschweig , Schleinitzstr. 22, 38106 Braunschweig, Germany
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Cattani-Scholz A. Functional Organophosphonate Interfaces for Nanotechnology: A Review. ACS APPLIED MATERIALS & INTERFACES 2017; 9:25643-25655. [PMID: 28671811 DOI: 10.1021/acsami.7b04382] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Optimization of interfaces in inorganic-organic device systems depends strongly on understanding both the molecular processes that are involved in surface modification and the effects that such modifications have on the electronic states of the material. In particular, the last several years have seen passivation and functionalization of semiconductor surfaces to be strategies by which to realize devices with superior function by controlling Fermi level energies, band-gap magnitudes, and work functions of semiconducting substrates. Among all of the synthetic routes and deposition methods available for the optimization of functional interfaces in hybrid systems, organophosphonate chemistry has been found to be a powerful tool to control at the molecular level the properties of materials in many different applications. In this Review, we focus on the relevance of organophosphonate chemistry in nanotechnology, giving an overview about some recent advances in surface modification, interface engineering, nanostructure optimization, and biointegration.
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Affiliation(s)
- Anna Cattani-Scholz
- Walter Schottky Institut and Technische Universität München , 85748 Garching, Germany
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Huang L, Chen L, Huang P, Wu F, Tan L, Xiao S, Zhong W, Sun L, Chen Y. Triple Dipole Effect from Self-Assembled Small-Molecules for High Performance Organic Photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:4852-4860. [PMID: 27115312 DOI: 10.1002/adma.201600197] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 02/24/2016] [Indexed: 06/05/2023]
Abstract
A novel triple dipole effect has been observed for Cl-assisted self-assembled small-molecules on ITO substrate, and a highest polymer solar cell performance of 9.2% is obtained.
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Affiliation(s)
- Liqiang Huang
- College of Chemistry/Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China
| | - Lie Chen
- College of Chemistry/Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China
| | - Pengru Huang
- Guangxi Key Laboratory of Information Materials, Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, 1 Jinji Road, Guilin, 541004, China
| | - Feiyan Wu
- College of Chemistry/Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China
| | - Licheng Tan
- College of Chemistry/Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China
| | - Shuqin Xiao
- College of Chemistry/Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China
| | - Wei Zhong
- School of Material Science and Engineering, Nanchang Hangkong University, 696 Fenghe South Avenue, Nanchang, 330063, China
| | - Lixian Sun
- Guangxi Key Laboratory of Information Materials, Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, 1 Jinji Road, Guilin, 541004, China
| | - Yiwang Chen
- College of Chemistry/Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China
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Abraham F, Ford WE, Scholz F, Nelles G, Sandford G, von Wrochem F. Surface Energy and Work Function Control of AlOx/Al Surfaces by Fluorinated Benzylphosphonic Acids. ACS APPLIED MATERIALS & INTERFACES 2016; 8:11857-11867. [PMID: 27093557 DOI: 10.1021/acsami.6b02012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The performance of organic electronic devices can be significantly improved by modifying metal electrodes with organic monolayers, which alter the physical and chemical nature of the interface between conductor and semiconductor. In this paper we examine a series of 12 phosphonic acid compounds deposited on the native oxide layer of aluminum (AlOx/Al), an electrode material with widespread applications in organic electronics. This series includes dodecylphosphonic acid as a reference and 11 benzylphosphonic acids, seven of which are fluorinated, including five newly synthesized derivatives. The monolayers are experimentally characterized by contact angle goniometry and by X-ray photoemission spectroscopy (XPS), and work function data obtained by low-intensity XPS are correlated with molecular dipoles obtained from DFT calculations. We find that monolayers are formed with molecular areas ranging from 17.7 to 42.9 Å(2)/molecule, and, by the choice of appropriate terminal groups, the surface energy can be tuned from 23.5 mJ/m(2) to 70.5 mJ/m(2). Depending on the number and position of fluorine substituents on the aromatic rings, a variation in the work function of AlOx/Al substrates over a range of 0.91 eV is achieved, and a renormalization procedure based on molecular density yields a surprising agreement of work function changes with interface dipoles as expected from Helmholtz' equation. The ability to adjust energetics and adhesion at organic semiconductor/AlOx interfaces has immediate applications in devices such as OLEDs, OTFTs, organic solar cells, and printed organic circuits.
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Affiliation(s)
- Ffion Abraham
- Department of Chemistry, Durham University , South Road, Durham DH1 3LE, U.K
| | - William E Ford
- Materials Science Laboratory, Sony Deutschland GmbH , Hedelfinger Strasse 61, 70327 Stuttgart, Germany
| | - Frank Scholz
- Materials Science Laboratory, Sony Deutschland GmbH , Hedelfinger Strasse 61, 70327 Stuttgart, Germany
| | - Gabriele Nelles
- Materials Science Laboratory, Sony Deutschland GmbH , Hedelfinger Strasse 61, 70327 Stuttgart, Germany
| | - Graham Sandford
- Department of Chemistry, Durham University , South Road, Durham DH1 3LE, U.K
| | - Florian von Wrochem
- Materials Science Laboratory, Sony Deutschland GmbH , Hedelfinger Strasse 61, 70327 Stuttgart, Germany
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Jabarullah NH, Verrelli E, Mauldin C, Navarro LA, Golden JH, Madianos LM, Kemp NT. Superhydrophobic SAM Modified Electrodes for Enhanced Current Limiting Properties in Intrinsic Conducting Polymer Surge Protection Devices. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:6253-6264. [PMID: 25996202 DOI: 10.1021/acs.langmuir.5b00686] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Surface interface engineering using superhydrophobic gold electrodes made with 1-dodecanethiol self-assembled monolayer (SAM) has been used to enhance the current limiting properties of novel surge protection devices based on the intrinsic conducting polymer, polyaniline doped with methanesulfonic acid. The resulting devices show significantly enhanced current limiting characteristics, including current saturation, foldback, and negative differential effects. We show how SAM modification changes the morphology of the polymer film directly adjacent to the electrodes, leading to the formation of an interfacial compact thin film that lowers the contact resistance at the Au-polymer interface. We attribute the enhanced current limiting properties of the devices to a combination of lower contact resistance and increased Joule heating within this interface region which during a current surge produces a current blocking resistive barrier due to a thermally induced dedoping effect caused by the rapid diffusion of moisture away from this region. The effect is exacerbated at higher applied voltages as the higher temperature leads to stronger depletion of charge carriers in this region, resulting in a negative differential resistance effect.
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Affiliation(s)
- Noor H Jabarullah
- †Department of Physics and Mathematics, University of Hull, Hull, United Kingdom HU6 7RX
- ∥Electrical Engineering, International College of Engineering, University Kuala Lumpur, British Malaysian Institute, 53100 Kuala Lumpur, Malaysia
| | - Emanuele Verrelli
- †Department of Physics and Mathematics, University of Hull, Hull, United Kingdom HU6 7RX
| | - Clayton Mauldin
- ‡TE Connectivity, Menlo Park, California 94025, United States
| | - Luis A Navarro
- ‡TE Connectivity, Menlo Park, California 94025, United States
| | - Josh H Golden
- ‡TE Connectivity, Menlo Park, California 94025, United States
| | - Leonidas M Madianos
- §Department of Physics, National Technical University of Athens, 15780 Zografou, Greece
| | - Neil T Kemp
- †Department of Physics and Mathematics, University of Hull, Hull, United Kingdom HU6 7RX
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MacLeod BA, Steirer KX, Young JL, Koldemir U, Sellinger A, Turner JA, Deutsch TG, Olson DC. Phosphonic Acid Modification of GaInP2 Photocathodes Toward Unbiased Photoelectrochemical Water Splitting. ACS APPLIED MATERIALS & INTERFACES 2015; 7:11346-11350. [PMID: 25970795 DOI: 10.1021/acsami.5b01814] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The p-type semiconductor GaInP2 has a nearly ideal bandgap (∼1.83 eV) for hydrogen fuel generation by photoelectrochemical water splitting but is unable to drive this reaction because of misalignment of the semiconductor band edges with the water redox half reactions. Here, we show that attachment of an appropriate conjugated phosphonic acid to the GaInP2 electrode surface improves the band edge alignment, closer to the desired overlap with the water redox potentials. We demonstrate that this surface modification approach is able to adjust the energetic position of the band edges by as much as 0.8 eV, showing that it may be possible to engineer the energetics at the semiconductor/electrolyte interface to allow for unbiased water splitting with a single photoelectrode having a bandgap of less than 2 eV.
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Affiliation(s)
| | | | - James L Young
- §Department of Materials Science and Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Unsal Koldemir
- ∥Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Alan Sellinger
- ∥Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, United States
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Nerngchamnong N, Wu H, Sotthewes K, Yuan L, Cao L, Roemer M, Lu J, Loh KP, Troadec C, Zandvliet HJW, Nijhuis CA. Supramolecular structure of self-assembled monolayers of ferrocenyl terminated n-alkanethiolates on gold surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13447-13455. [PMID: 25325611 DOI: 10.1021/la503493x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
It is important to understand the structure of redox-active self-assembled monolayers (SAMs) down to the atomic scale, since these SAMS are widely used as model systems in studies of mechanisms of charge transport or to realize electronic functionality in molecular electronic devices. We studied the supramolecular structure of SAMs of n-alkanethiolates with ferrocenyl (Fc) end groups (S(CH2)nFc, n = 3 or 4) on Au(111) by scanning tunneling microscopy (STM). In this system, the tilt angle of the Fc units with respect to the surface normal (α) depends on the value of n because the Au-S-C bond angle is fixed. The ordered domains of the SAMs were imaged by STM after annealing at 70 °C at ultrahigh vacuum conditions. High resolution electron energy loss spectroscopy (HREELS) and cyclic voltammetry show that this annealing step only removed physisorbed material and did not affect the structure of the SAM. The STM images revealed the presence of row defects at intervals of 4 nm, that is, six molecules. We determined by near edge X-ray absorption fine structure spectroscopy (NEXAFS) that the Fc units of the SAMs of SC3Fc are more parallel to the Au(111) plane with a tilt angle α = 60.2° than the Fc units of SC4Fc SAMs (α = 45.4°). These tilt angles are remarkably close to the tilt angles measured by X-ray diffraction data of bulk crystals (bc-plane). Based on our data, we conclude that the molecules are standing up and the SAMs pack into lattices that are distorted from their bulk crystal structures (because of the build-up stain due to the differences in size between the Fc units and thiolate anchoring groups).
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Affiliation(s)
- Nisachol Nerngchamnong
- Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543
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Shao G, Glaz MS, Ma F, Ju H, Ginger DS. Intensity-modulated scanning Kelvin probe microscopy for probing recombination in organic photovoltaics. ACS NANO 2014; 8:10799-10807. [PMID: 25207675 DOI: 10.1021/nn5045867] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We study surface photovoltage decays on sub-millisecond time scales in organic solar cells using intensity-modulated scanning Kelvin probe microscopy (SKPM). Using polymer/fullerene (poly[N-9"-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]/[6,6]-phenyl C71-butyric acid methyl ester, PCDTBT/PC71BM) bulk heterojunction devices as a test case, we show that the decay lifetimes measured by SKPM depend on the intensity of the background illumination. We propose that this intensity dependence is related to the well-known carrier-density-dependent recombination kinetics in organic bulk heterojunction materials. We perform transient photovoltage (TPV) and charge extraction (CE) measurements on the PCDTBT/PC71BM blends to extract the carrier-density dependence of the recombination lifetime in our samples, and we find that the device TPV and CE data are in good agreement with the intensity and frequency dependence observed via SKPM. Finally, we demonstrate the capability of intensity-modulated SKPM to probe local recombination rates due to buried interfaces in organic photovoltaics (OPVs). We measure the differences in photovoltage decay lifetimes over regions of an OPV cell fabricated on an indium tin oxide electrode patterned with two different phosphonic acid monolayers known to affect carrier lifetime.
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Affiliation(s)
- Guozheng Shao
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
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15
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Mu X, Guo S, Zhang L, Yang P. Modification of indium tin oxide with persulfate-based photochemistry toward facile, rapid, and low-temperature interface-mediated multicomponent assembling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4945-4951. [PMID: 24716839 DOI: 10.1021/la5004963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The well-controlled material assembly and patterning on indium tin oxide (ITO) coating layer is of great importance for the practical fabrication of a functional device. Nonetheless, the conventional way to achieve this aim is still mainly based on the combination of photolithography with pattern transfer techniques (e.g., wet/dry etching, μCP) due to the lack of one method that is able to directly afford site-selective ITO surface tailoring and subsequent templating for material assembly. Herein, we reported a novel, fast, and efficient photochemical reaction to accurately tailor the surface property of ITO with light-controlled site-selectivity, thus resulting in direct photoresist-free and etching/contact-free lithographic patterning of building blocks, e.g., ZnO, BaTiO3, CdS, lipid membrane, conductive polymers, colloids, and liquid crystals. The entire process reveals new interfacial chemistry suitable for inorganic metal oxide and its important versatile implications for low-cost fabrication of large-area flat and flexible optical/electronic/biorelated devices.
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Affiliation(s)
- Xiaoyan Mu
- Key Laboratory of Applied Surface and Colloids Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University , Xìan, 710119 China
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Gliboff M, Sang L, Knesting KM, Schalnat MC, Mudalige A, Ratcliff EL, Li H, Sigdel AK, Giordano AJ, Berry JJ, Nordlund D, Seidler GT, Brédas JL, Marder SR, Pemberton JE, Ginger DS. Orientation of phenylphosphonic acid self-assembled monolayers on a transparent conductive oxide: a combined NEXAFS, PM-IRRAS, and DFT study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2166-2174. [PMID: 23379837 DOI: 10.1021/la304594t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Self-assembled monolayers (SAMs) of dipolar phosphonic acids can tailor the interface between organic semiconductors and transparent conductive oxides. When used in optoelectronic devices such as organic light emitting diodes and solar cells, these SAMs can increase current density and photovoltaic performance. The molecular ordering and conformation adopted by the SAMs determine properties such as work function and wettability at these critical interfaces. We combine angle-dependent near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) to determine the molecular orientations of a model phenylphosphonic acid on indium zinc oxide, and correlate the resulting values with density functional theory (DFT). We find that the SAMs are surprisingly well-oriented, with the phenyl ring adopting a well-defined tilt angle of 12-16° from the surface normal. We find quantitative agreement between the two experimental techniques and density functional theory calculations. These results not only provide a detailed picture of the molecular structure of a technologically important class of SAMs, but also resolve a long-standing ambiguity regarding the vibrational-mode assignments for phosphonic acids on oxide surfaces, thus improving the utility of PM-IRRAS for future studies.
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Affiliation(s)
- Matthew Gliboff
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, United States
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Guerrero G, Alauzun JG, Granier M, Laurencin D, Mutin PH. Phosphonate coupling molecules for the control of surface/interface properties and the synthesis of nanomaterials. Dalton Trans 2013; 42:12569-85. [DOI: 10.1039/c3dt51193f] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Hauffman T, Hubin A, Terryn H. Study of the self-assembling of n-octylphosphonic acid layers on aluminum oxide from ethanolic solutions. SURF INTERFACE ANAL 2012. [DOI: 10.1002/sia.5150] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Tom Hauffman
- Department of Electrochemical and Surface Engineering; Vrije Universiteit Brussel; Pleinlaan 2; 1050; Brussels; Belgium
| | - Annick Hubin
- Department of Electrochemical and Surface Engineering; Vrije Universiteit Brussel; Pleinlaan 2; 1050; Brussels; Belgium
| | - Herman Terryn
- Department of Electrochemical and Surface Engineering; Vrije Universiteit Brussel; Pleinlaan 2; 1050; Brussels; Belgium
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MacLeod BA, Horwitz NE, Ratcliff EL, Jenkins JL, Armstrong NR, Giordano AJ, Hotchkiss PJ, Marder SR, Campbell CT, Ginger DS. Built-In Potential in Conjugated Polymer Diodes with Changing Anode Work Function: Interfacial States and Deviation from the Schottky-Mott Limit. J Phys Chem Lett 2012; 3:1202-1207. [PMID: 26288056 DOI: 10.1021/jz300283h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We use electroabsorption spectroscopy to measure the change in built-in potential (VBI) across the polymer photoactive layer in diodes where indium tin oxide electrodes are systematically modified using dipolar phosphonic acid self-assembled monolayers (SAMs) with various dipole moments. We find that VBI scales linearly with the work function (Φ) of the SAM-modified electrode over a wide range when using a solution-coated poly(p-phenylenevinylene) derivative as the active layer. However, we measure an interfacial parameter of S = eΔVBI/ΔΦ < 1, suggesting that these ITO/SAM/polymer interfaces deviate from the Schottky-Mott limit, in contrast to what has previously been reported for a number of ambient-processed organic-on-electrode systems. Our results suggest that the energetics at these ITO/SAM/polymer interfaces behave more like metal/organic interfaces previously studied in UHV despite being processed from solution.
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Affiliation(s)
- Bradley A MacLeod
- †Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Noah E Horwitz
- †Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Erin L Ratcliff
- ‡Department of Chemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Judith L Jenkins
- ‡Department of Chemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Neal R Armstrong
- ‡Department of Chemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Anthony J Giordano
- §School of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Peter J Hotchkiss
- §School of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Seth R Marder
- §School of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Charles T Campbell
- †Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - David S Ginger
- †Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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