A5079675149- Organic Electronics and Photovoltaics
- Organic Light-Emitting Diodes Research
- Conducting polymers and applications
- Semiconductor materials and devices
- Silicon Nanostructures and Photoluminescence
- Molecular Junctions and Nanostructures
- Nanowire Synthesis and Applications
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and interfaces
- Thin-Film Transistor Technologies
- Advanced Memory and Neural Computing
- Electron and X-Ray Spectroscopy Techniques
- Quantum Dots Synthesis And Properties
- Luminescence and Fluorescent Materials
- Quantum and electron transport phenomena
- Neuroscience and Neural Engineering
- Chalcogenide Semiconductor Thin Films
- GaN-based semiconductor devices and materials
- Anodic Oxide Films and Nanostructures
- Organic and Molecular Conductors Research
- Perovskite Materials and Applications
- Surface and Thin Film Phenomena
- Electronic and Structural Properties of Oxides
- Graphene research and applications
- Photocathodes and Microchannel Plates
Central South University of Forestry and Technology
2025
Central South University
2025
Fudan University
2014-2024
State Key Laboratory of Surface Physics
1998-2024
Collaborative Innovation Center of Advanced Microstructures
2015-2023
Beihang University
2022
Guizhou University
2022
University of Hong Kong
2010
National Synchrotron Radiation Laboratory
2009
University of Science and Technology of China
2009
Direct measurements of electronic properties have been made for the metal/organic and organic/organic interfaces in a multilayer organic light-emitting diode (LED) using ultraviolet photoemission spectroscopy. The device configuration considered is indium–tin oxide (ITO)/copper phthalocyanine (CuPc)/N,N′-bis-(1-naphyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamne (NPB)/8-hydroxyquinoline aluminum (Alq)/Mg. For material here, our result indicates that traditional concept vacuum-level alignment,...
Solar cells and optical detection devices often incorporate antireflective surfaces to reduce undesired reflection enhance absorption. This letter reports a “black silicon” structure of porous silicon fabricated by using electrochemical etching. The sample has gradient-index multilayer structure, i.e., the refraction indices increase from top (near air) bottom Si substrate). Reflectance below 5% is obtained over broad wave number range (3000–28000cm−1) depression mechanism reflectance...
Organic light-emitting diodes (OLEDs) have enjoyed significant progress in terms of practical applications; however, their lifetimes are often limited by poor thermal stability. These authors monitored the surface temperature working OLED devices and identified "hot spots" due to electrical shorting using an infrared imaging analysis system. Thermal breakdown is shown its origins electric-field-induced decomposition indium tin oxide electromigration through organic layer under high electric field.
The energy level alignment for both Mg/8-hydroxyquinoline aluminum (Alq) and Au/Alq interfaces has been determined by the ultraviolet photoemission measurements. For interfaces, difference between Fermi low-energy edge of highest occupied molecular orbital (HOMO) is around 1.7 eV. This implies that with respect to HOMO Alq independent work function Mg Au despite a large in metal function. A model proposed, invoking charge transfer formation dipolar layer at metal/Alq interface.
The chelate phosphine oxide ligand bis(2-(diphenylphosphino)phenyl) ether (DPEPO) was used as a unit neutral to prepare the complex Eu(TTA)(3)(DPEPO) 1 (TTA = 2-thenoyltrifluoroacetonate). Compound has photoluminescence (PL) quantum yield of 55.3%, which is more than twice PL Eu(TTA)(3)(TPPO)(2) (TPPO triphenylphosphine oxide). Investigation indicated that DPEPO in mezzo first triplet excited energy level (T(1)) between singlet (S(1)) and T(1) TTA, may support one additional transfer...
The correlation between the Raman peak shift and linewidth of porous silicon is studied. experimental result does not fit with relationship predicted by phonon confinement model. By taking into account both effect strain, calculated line shape coincides fairly well measured spectrum. built-in strain varies porosity sample on order 10−3.
The multicarrier hopping process in disordered organic materials is studied via Monte Carlo simulations taking into consideration both the site exclusion effect and Coulomb interaction. carrier mobility with Gaussian energetic disorder found to depend heavily on density. At high densities, interaction reduce low intrinsic or at temperatures, enhance temperatures.
Three cationic PPEs P1'−P3' were obtained through quaternization of their neutral polymers, which all side chains respectively featured with a tertiary amino group (P1), an alternative and tri(ethylene glycol)methyl ether (P2), dodecyloxy (P3). P1' showed intrinsic water-solubility although its degree was only 45%. Slightly blue-shifted UV−vis absorption maxima in acidic environment (maximal Δλmax ≈ 3 nm) obvious red-shifted 30 emission 20 alkaline at pH < 13 are explained terms pH-induced...
Small-molecule organic solar cells with a structure of indium tin oxide (ITO)\tris-8-hydroxy-quinolinato aluminum (Alq3) (2nm)\fullerene (C60) (40nm)\copper phthalocyanine (CuPc) (32nm)\Au (40nm) were fabricated. The shelf lifetime unencapsulated devices was over 1500h, and the power conversion efficiency reached 0.76% under AM1.5G (air mass 1.5 global) 75mW∕cm2. long attributed to inverted compared conventional ITO\CuPc\C60\buffer\Al since former could effectively protect C60 from diffusion...
Ultraviolet photoelectron spectroscopy has been applied to the investigation of modified hole injection barriers in organic light-emitting devices (OLEDs). Different from those reported previously, indium tin oxide (ITO) surface treated situ by oxygen plasma possesses a work function 5.2 eV, and ITO interface thereafter formed shows 0.5 eV smaller barrier compared that on untreated ITO. Insertion an ultrathin SiO2 layer between results similar reduction barrier. This indicates improved...
A boiling water treatment of light emitting porous silicon can give rise to a large blue shift its photoluminescence spectrum and meanwhile strengthen the skeleton Si by filling up many pores with aqueous oxide. stable blue-green emission at peak wavelength down 500 nm is achieved. FTIR measurements show that formation dihydride on sidewall surfaces rods not responsible visible luminescence for very thin wires.
Based on the WKB approximation of tunneling model, we calculate J–V characteristics organic light-emitting devices (OLEDs) having buffer layers different thickness. The results show how insertion a layer with proper thickness lowers OLED turn-on voltage. Further calculation suggests some parameters, such as resistivity ratio and position conduction band minimum relative to lowest unoccupied molecular orbital layer, are important in selecting material. A quantitative estimation optimal is...
A thin buffer layer is indispensable for a high power conversion efficiency in an organic solar cell with fullerene (C60) as the acceptor. In present work, authors proposed that role of to prohibit electron transfer from metal C60, and thus desired built-in electric field can promote free carrier collection. The different cells without C60 was studied by transient photovoltage technique. experimental results supported our proposal indicated exciton blocking effect reported literature might...
Three new phenyl-substituted poly(p-phenylenevinylene) (Ph−PPV) derivatives with amino-functionalized groups were synthesized through either Gilch reaction for poly{2,5-bis[4'-2-(N,N-diethylamino)ethoxyphenyl]-1,4-phenylenevinylene (P1) or Wittig poly{2,5-bis(4'-decyloxyphenyl)-1,4-phenylenevinylene-alt-2,5-bis[4'-2-(N,N-diethylamino)ethoxyphenyl]-1,4-phenylenevinylene} (P2) and...
We report the fabrication of a vacuum-deposited light-emitting device which emits light from its top surface through an Al cathode using p-type doped silicon as anode material. Enhanced hole injection is clearly demonstrated p-Si compared to indium–tin–oxide (ITO) anode. The mechanisms both and ITO anodes into organic layer are investigated possible model based on band bending proposed. During operation device, plays very important role in modifying interfacial barrier height between layer.
It is demonstrated experimentally that the effect of a LiF buffer layer inserted at ITO\N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′ biphenyl 4,4′-dimaine (NPB) interface on hole injection greatly dependent initial barrier height (IBH) existing interface. Only for large IBH, will introduction show improvement effect. For small one, it weaken injection. These phenomena are explained in terms tunneling model and calculations based this good agreement with experimental results. This further confirms...
A LiF-buffered silver cathode has been used in organic light-emitting devices (OLEDs) with structure indium–tin–oxide/N,N′-bis-(1-naphthl)-diphenyl-1,1′-biphenyl-4,4′-diamine (50 nm)/Alq3 (100 nm)/cathode. The efficiency of electron injection from the is strongly dependent on thickness LiF buffer layer. While a layer thinner than 1.0 nm leads to higher turn-on voltage and decreased electroluminescent (EL) efficiency, 3.0 significantly enhances results lower increased EL efficiency....
The current density-luminance-voltage characteristics of organic light-emitting devices (OLEDs) with N,N′-Bis(naphthalen-1-yl)-N,N′-bis(phenyl) benzidine (NPB) various thicknesses as the hole transport layer have been investigated. It is found that for conventional structures indium–tin–oxide/NPB/tris(8-hydroxyquinoline) aluminum (Alq3) (60 nm)/LiF (0.5 nm)/Al optimal injection and luminescence efficiencies appear at NPB 5 20 nm, respectively. large difference between two suggests effective...
We demonstrate for the first time that a porous silicon layer (PSL), which has bright light-emission band in range of 500--700 nm, exhibits strong visible-range luminescence under illumination an infrared ultrashort pulsed laser. The dependence integrated intensity on pump power shows this is third-order nonlinear optical effect. By comparing with UV-light-excited spectra PSL and samples low porosity have inefficient luminescence, possible explanation proposed whereby large response due to...