A5020377856- Organic Electronics and Photovoltaics
- Molecular Junctions and Nanostructures
- Conducting polymers and applications
- Organic Light-Emitting Diodes Research
- Perovskite Materials and Applications
- Semiconductor materials and devices
- Surface and Thin Film Phenomena
- Electron and X-Ray Spectroscopy Techniques
- Advanced Chemical Physics Studies
- Quantum Dots Synthesis And Properties
- Semiconductor materials and interfaces
- Chalcogenide Semiconductor Thin Films
- Thin-Film Transistor Technologies
- Advanced Memory and Neural Computing
- Semiconductor Quantum Structures and Devices
- Silicon and Solar Cell Technologies
- Nanowire Synthesis and Applications
- Ga2O3 and related materials
- Fullerene Chemistry and Applications
- Electronic and Structural Properties of Oxides
- Machine Learning in Materials Science
- Force Microscopy Techniques and Applications
- GaN-based semiconductor devices and materials
- Electrochemical Analysis and Applications
- X-ray Diffraction in Crystallography
Princeton University
2016-2025
Princeton Public Schools
2014-2021
Tianjin University
2019
Weizmann Institute of Science
2005-2017
CEA LITEN
2016
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016
Université Grenoble Alpes
2016
Université de Lille
2016
Centre National de la Recherche Scientifique
2016
Georgia Institute of Technology
2005-2015
Organic and printed electronics technologies require conductors with a work function that is sufficiently low to facilitate the transport of electrons in out various optoelectronic devices. We show surface modifiers based on polymers containing simple aliphatic amine groups substantially reduce including metals, transparent conductive metal oxides, conducting polymers, graphene. The reduction arises from physisorption neutral polymer, which turns modified into efficient electron-selective...
Abstract The field of organic thin films and devices is progressing at an extremely rapid pace. Organic–metal organic–organic interfaces play crucial roles in charge injection into, transport through, these devices. Their electronic structure, chemical properties, electrical behavior must be fully characterized understood if the engineering control are to reach levels obtained for inorganic semiconductor This article provides extensive, although admittedly nonexhaustive, review experimental...
Electronic levels and energies of a solid, such as Fermi level, vacuum work function, ionization energy or electron affinity, are paramount importance for the control device behavior, charge carrier injection transport.
We demonstrate the improvement of an indium tin oxide anode contact to organic light emitting device via oxygen plasma treatment. Enhanced hole-injection efficiency improves dramatically performance single-layer doped-polymer devices: drive voltage drops from >20 <10 V, external electroluminescence quantum (backside emission only) increases by a factor 4 (from 0.28% 1%), much higher current can be applied achieve brightness (maximum ∼10,000 cd/m2 at 1000 mA/cm2), and...
Abstract We present a concise, although admittedly non‐exhaustive, but hopefully didactic review and discussion of some the central basic concepts related to energetics surfaces interfaces solids. This is particular importance for that involve organic molecules molecular films. It attempts pull together different views terminologies used in solid state, electrochemistry, electronic device communities, regarding key local absolute vacuum level, surface dipole, work function, electron...
Direct and inverse photoemission spectroscopies are used to determine materials electronic structure energy level alignment in hybrid organic–inorganic perovskite layers grown on TiO2. The results provide a quantitative basis for the analysis of perovskite-based solar cell performance choice an optimal hole-extraction layer.
The electronic structures of vacuum-deposited molybdenum trioxide (MoO3) and a typical MoO3/hole transport material (HTM) interface are determined via ultraviolet inverse photoelectron spectroscopy. Electron affinity ionization energy MoO3 found to be 6.7 9.68 eV, more than 4 eV larger generally assumed, leading revised interpretation the role in hole injection organic devices. films strongly n-type. structure oxide/HTM shows that proceeds electron extraction from HTM highest occupied...
The reorganization energy in pentacene is reported on the basis of a joint experimental and theoretical study ionization using high-resolution gas-phase photoelectron spectroscopy, semiempirical intermediate neglect differential overlap calculations, first-principles correlated quantum-mechanical calculations at MP2 density functional theory levels. upon positive determined both experimentally theoretically to be remarkably low. This one key element that allows rationalize extremely high...
In order to clarify the electronic structure of metal-molecular semiconductor contacts, we use photoemission spectroscopy investigate energetics interfaces formed by vacuum deposition four different molecular thin films on various metals. We find that interface electron and hole barriers are not simply defined difference between work functions metals organic solids. The range Fermi level positions is material dependent dipole present at all these interfaces. results demonstrate breakdown...
The conclusions reached by a diverse group of scientists who attended an intense 2-day workshop on hybrid organic-inorganic perovskites are presented, including their thoughts the most burning fundamental and practical questions regarding this unique class materials, suggestions various approaches to resolve these issues.
The characterization and implementation of solution-processed, wide bandgap nickel oxide (NiOx) hole-selective interlayer materials used in bulk-heterojunction (BHJ) organic photovoltaics (OPVs) are discussed. surface electrical properties charge selectivity these thin films strongly dependent upon the chemistry, band edge energies, midgap state concentrations, as dictated by ambient conditions film pretreatments. Surface states were correlated with standards for oxide, hydroxide,...
We report valence and conduction band densities of states measured via ultraviolet inverse photoemission spectroscopies on three metal halide perovskites, specifically methylammonium lead iodide bromide cesium (MAPbI3, MAPbBr3, CsPbBr3), grown at two different institutions substrates. These are compared with theoretical (DOS) calculated density functional theory. The qualitative agreement achieved between experiment theory leads to the identification spectral features, allows a precise...
MoO3 films spin-coated from a suspension of nanoparticles, which offers energetic properties nearly identical to those thermally evaporated films, are reported. It is demonstrated that our solution-based acts as very efficient hole-injection layer for organic devices. Detailed facts importance specialist readers published "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by the authors. Please note: The publisher responsible...
Abstract We show enhanced efficiency and stability of a high performance organic solar cell (OPV) when the work‐function hole collecting indium‐tin oxide (ITO) contact, modified with solution‐processed nickel (NiO x ) hole‐transport layer (HTL), is matched to ionization potential donor material in bulk‐heterojunction cell. Addition NiO HTL contact results power conversion ( PCE 6.7%, which 17.3% net increase over 5.7% achieved poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)...
Tail states in organic semiconductors have a significant influence on device performances by acting as traps charge transport. We present study of the controlled passivation acceptor tail fullerene ${\mathrm{C}}_{60}$ addition electrons introduced molecular $n$ doping. Using ultralow doping, we are able to successively fill with charges and examine changes conductivity, activation energy, mobility, Fermi-level position. Passivation leads an increase electron mobility more than 3 orders...
The electronic structure of Vanadium pentoxide (V2O5), a transition metal oxide with an exceedingly large work function 7.0 eV, is studied via ultraviolet, inverse and x-ray photoemission spectroscopy. Very deep lying states electron affinity ionization energy (IE) 6.7 eV 9.5 respectively, are found. Contamination due to air exposure changes the partial reduction vanadium V+4 state. It shown that V2O5 n-type material can be used for efficient hole-injection into materials IE larger than 6...
Abstract For large‐scale and high‐throughput production of organic solar cells (OSCs), liquid processing the functional layers is desired. We demonstrate inverted bulk‐heterojunction (OSCs) with a sol–gel derived V 2 O 5 hole‐extraction‐layer on top active layer. The are prepared in ambient air using Vanadium(V)‐oxitriisopropoxide as precursor. Without any post‐annealing or plasma treatment, high work function confirmed by both Kelvin probe analysis ultraviolet photoelectron spectroscopy...
The discovery of air-stable n-dopants for organic semiconductor materials has been hindered by the necessity high-energy HOMOs and air sensitivity compounds that satisfy this requirement. One strategy circumventing problem is to utilize stable precursor molecules form active doping complex in situ during process or a postdeposition thermal- photo-activation step. Some us have reported on use 1H-benzimidazole (DMBI) benzimidazolium (DMBI-I) salts as solution- vacuum-processable n-type dopant...