Andreas Opitz
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View article: Molecular Doping Induced Charge Transfer Complex Formation and Interfacial Dopant Interdiffusion on Graphite
Molecular Doping Induced Charge Transfer Complex Formation and Interfacial Dopant Interdiffusion on Graphite Open
View article: A novel <i>n</i>‐type dimer dopant for semiconducting polymers
A novel <i>n</i>‐type dimer dopant for semiconducting polymers Open
Efficient and stable doping of organic semiconductors is crucial for adjusting their electrical properties. This work focuses on a novel n ‐type dopant which releases two electrons per dopant molecule. The dopant's capability was tested wi…
View article: Unveiling the Role of Solvents in DBTTF:HATCN Ternary Cocrystals
Unveiling the Role of Solvents in DBTTF:HATCN Ternary Cocrystals Open
Donor-acceptor (D:A) cocrystals offer a promising platform for next-generation optoelectronic applications, but the impact of residual solvent molecules on their properties remains an open question. We investigate six novel D:A cocrystals …
View article: Two Isomeric Thienoacenes in Thin Films: Unveiling the Influence of Molecular Structure and Intermolecular Packing on Electronic Properties
Two Isomeric Thienoacenes in Thin Films: Unveiling the Influence of Molecular Structure and Intermolecular Packing on Electronic Properties Open
Isomerism of molecular structures is often encountered in the field of organic semiconductors, but little is known about how it can impact electronic and charge transport properties in thin films. This study reveals the molecular orientati…
View article: Role of the Solvent on the Orientation of Y-Type Acceptor Molecules in Spin-Coated Films
Role of the Solvent on the Orientation of Y-Type Acceptor Molecules in Spin-Coated Films Open
In this study, a rational processing strategy is presented, aiming to achieve well-ordered thin films of the molecular electron acceptors Y5 and Y6 by the choice of solvent as a key parameter. The thin films were spin-coated from chloroben…
View article: Non-equilibrium transport in polymer mixed ionic–electronic conductors at ultrahigh charge densities
Non-equilibrium transport in polymer mixed ionic–electronic conductors at ultrahigh charge densities Open
Conducting polymers are mixed ionic–electronic conductors that are emerging candidates for neuromorphic computing, bioelectronics and thermoelectrics. However, fundamental aspects of their many-body correlated electron–ion transport physic…
View article: Terrylene on monolayer WS<sub>2</sub>: coverage-dependent molecular re-orientation and interfacial electronic energy levels
Terrylene on monolayer WS<sub>2</sub>: coverage-dependent molecular re-orientation and interfacial electronic energy levels Open
Molecular orientation and energy level alignment at interfaces between terrylene and monolayer WS 2 change substantially as a function of molecular coverage.
View article: Laser-induced tuning of crystallization in tetracene thin films
Laser-induced tuning of crystallization in tetracene thin films Open
Laser illumination acts a novel growth parameter for thin films, leading to larger crystallite size and molecular alignment in tetracene growth. Laser control is distinct from traditional thermal growth and paves the way for novel material…
View article: Coordination of Tetracyanoquinodimethane-Derivatives with Tris(pentafluorophenyl)borane Provides Stronger p-Dopants with Enhanced Stability
Coordination of Tetracyanoquinodimethane-Derivatives with Tris(pentafluorophenyl)borane Provides Stronger p-Dopants with Enhanced Stability Open
Strong molecular dopants for organic semiconductors that are stable against diffusion are in demand, enhancing the performance of organic optoelectronic devices. The conventionally used p-dopants based on 7,7,8,8-tetracyanoquinodimethane (…
View article: Spectral Signatures of a Negative Polaron in a Doped Polymer Semiconductor: Energy Levels and Hubbard <i>U</i> Interactions
Spectral Signatures of a Negative Polaron in a Doped Polymer Semiconductor: Energy Levels and Hubbard <i>U</i> Interactions Open
The modern picture of negative charge carriers on conjugated polymers invokes the formation of a singly occupied (spin-up/spin-down) level within the polymer gap and a corresponding unoccupied level above the polymer conduction band edge. …
View article: Improving the Resistance of Molecularly Doped Polymer Semiconductor Layers to Solvent
Improving the Resistance of Molecularly Doped Polymer Semiconductor Layers to Solvent Open
The ability to form multi-heterolayer (opto)electronic devices by solution processing of (molecularly doped) semiconducting polymer layers is of great interest since it can facilitate the fabrication of large-area and low-cost devices. How…
View article: Surface doping of rubrene single crystals by molecular electron donors and acceptors
Surface doping of rubrene single crystals by molecular electron donors and acceptors Open
Surface transfer doping with molecular donors/acceptors enables controlling the Fermi level position of rubrene single crystal surfaces without disrupting the electronic band structure.
View article: Use of a Multiple Hydride Donor To Achieve an n-Doped Polymer with High Solvent Resistance
Use of a Multiple Hydride Donor To Achieve an n-Doped Polymer with High Solvent Resistance Open
The ability to insolubilize doped semiconducting polymer layers can help enable the fabrication of efficient multilayer solution-processed electronic and optoelectronic devices. Here, we present a promising approach to simultaneously n-dop…
View article: Quantum Efficiency Enhancement of Lead-Halide Perovskite Nanocrystal LEDs by Organic Lithium Salt Treatment
Quantum Efficiency Enhancement of Lead-Halide Perovskite Nanocrystal LEDs by Organic Lithium Salt Treatment Open
Surface-defect passivation is key to achieving high photoluminescence quantum yield in lead halide perovskite nanocrystals. However, in perovskite light-emitting diodes these surface ligands also have to enable balanced charge injection in…
View article: Photooxidation of PC<sub>60</sub>BM: new insights from spectroscopy
Photooxidation of PC<sub>60</sub>BM: new insights from spectroscopy Open
The combination of XPS, NEXAFS and FTIR spectroscopy with DFT calculations reveals clear fingerprints of the photooxidation products of PC 60 BM films under ambient conditions.
View article: Understanding the evolution of the Raman spectra of molecularly p-doped poly(3-hexylthiophene-2,5-diyl): signatures of polarons and bipolarons
Understanding the evolution of the Raman spectra of molecularly p-doped poly(3-hexylthiophene-2,5-diyl): signatures of polarons and bipolarons Open
Experimental Raman spectra of molecularly doped P3HT thin films are combined with first-principles calculations on oligomer models to understand and identify the fingerprints for polarons and bipolarons in doped P3HT.
View article: Thin films of electron donor–acceptor complexes: characterisation of mixed-crystalline phases and implications for electrical doping
Thin films of electron donor–acceptor complexes: characterisation of mixed-crystalline phases and implications for electrical doping Open
For electron donor–acceptor complexes a link will be established between optical, structural and vibrational properties of EDA complexes as well as the electrical doping by them.
View article: Coupled Organic–Inorganic Nanostructures with Mixed Organic Linker Molecules
Coupled Organic–Inorganic Nanostructures with Mixed Organic Linker Molecules Open
The electronic properties of semiconducting inorganic lead sulfide (PbS) nanocrystals (NCs) and organic linker molecules are dependent on the size of NCs as well as the used ligands. Here, we demonstrate that a weakly binding ligand can be…
View article: Disentangling Bulk and Interface Phenomena in a Molecularly Doped Polymer Semiconductor
Disentangling Bulk and Interface Phenomena in a Molecularly Doped Polymer Semiconductor Open
Doping the electron‐transport polymer poly{[ N , N ′‐bis(2‐octyldodecyl)naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} [P(NDI2OD‐T 2 )] with the bulky, strongly reducing metallocene 1,2,3,4,1′,2′,3′,4′‐octaph…
View article: Conductive Polymer Work Function Changes due to Residual Water: Impact of Temperature‐Dependent Dielectric Constant
Conductive Polymer Work Function Changes due to Residual Water: Impact of Temperature‐Dependent Dielectric Constant Open
Solution‐processed conducting polymer thin films are key components in organic and flexible electronic and optoelectronic devices. An archetypal conducting polymer is poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS), whi…
View article: An Organic Borate Salt with Superior <i>p</i>‐Doping Capability for Organic Semiconductors
An Organic Borate Salt with Superior <i>p</i>‐Doping Capability for Organic Semiconductors Open
Molecular doping allows enhancement and precise control of electrical properties of organic semiconductors, and is thus of central technological relevance for organic (opto‐) electronics. Beyond single‐component molecular electron acceptor…
View article: Single-Step Formation of a Low Work Function Cathode Interlayer and n-type Bulk Doping from Semiconducting Polymer/Polyethylenimine Blend Solution
Single-Step Formation of a Low Work Function Cathode Interlayer and n-type Bulk Doping from Semiconducting Polymer/Polyethylenimine Blend Solution Open
The use of polyethylenimine (PEI) as a thin interlayer between cathodes and organic semiconductors in order to reduce interfacial Ohmic losses has become an important approach in organic electronics. It has also been shown that such interl…
View article: Electrode Work Function Reduction by Polyethylenimine Interlayers: Choice of Solvent and Residual Solvent Removal for Superior Functionality
Electrode Work Function Reduction by Polyethylenimine Interlayers: Choice of Solvent and Residual Solvent Removal for Superior Functionality Open
Ultrathin polyethylenimine (PEI) interlayers are frequently used to reduce the work function of electrode materials; however, to exploit the full potential of this material for application in optoelectronic devices, further fundamental und…
View article: The optical signatures of molecular-doping induced polarons in poly(3-hexylthiophene-2,5-diyl): individual polymer chains<i>versus</i>aggregates
The optical signatures of molecular-doping induced polarons in poly(3-hexylthiophene-2,5-diyl): individual polymer chains<i>versus</i>aggregates Open
For molecularly doped poly(3-hexyl-thiophene) solvated individual chains can be unambiguously differentiated from aggregated ones by diagnostic polaron absorption.
View article: Fermi level pinned molecular donor/acceptor junctions: reduction of induced carrier density by interfacial charge transfer complexes
Fermi level pinned molecular donor/acceptor junctions: reduction of induced carrier density by interfacial charge transfer complexes Open
Charge transfer complex (CPX) formation at a donor–acceptor interface reduces the amount of Fermi-level pinning induced interfacial charge transfer.
View article: Utilizing Diels–Alder “click” chemistry to functionalize the organic–organic interface of semiconducting polymers
Utilizing Diels–Alder “click” chemistry to functionalize the organic–organic interface of semiconducting polymers Open
An all-solution-based modular functionalization of a cross-linked polymer semiconductor interface is presented. The thus covalently introduced moieties can be utilised for tailor-made organic–organic interfaces in organic optoelectronic de…
View article: Electronic band dispersion determination in azimuthally disordered transition-metal dichalcogenide monolayers
Electronic band dispersion determination in azimuthally disordered transition-metal dichalcogenide monolayers Open
View article: Impact of intentional photo-oxidation of a donor polymer and PC<sub>70</sub>BM on solar cell performance
Impact of intentional photo-oxidation of a donor polymer and PC<sub>70</sub>BM on solar cell performance Open
Bond breaking in the PC70BM cage and gap state formation explain inefficient charge collection upon photooxidation.
View article: Microstructure and Elastic Constants of Transition Metal Dichalcogenide Monolayers from Friction and Shear Force Microscopy
Microstructure and Elastic Constants of Transition Metal Dichalcogenide Monolayers from Friction and Shear Force Microscopy Open
Optical and electrical properties of 2D transition metal dichalcogenides (TMDCs) grown by chemical vapor deposition (CVD) are strongly determined by their microstructure. Consequently, the visualization of spatial structural variations is …
View article: Low temperature processed NiOx hole transport layers for efficient polymer solar cells
Low temperature processed NiOx hole transport layers for efficient polymer solar cells Open