Ralph H. Young

University of Rochester

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Denis Y. Kondakov

Wilmington University

Samir Farid

University of Rochester

Alfred P. Marchetti

University of Rochester

Thomas D. Pawlik

Carestream (United States)

Walter J. Deal

University of California, Riverside

Joseph C. Deaton

North Carolina State University

Ian R. Gould

Imperial College London

Marina Kondakova

OLEDWorks (United States)

David J. Giesen

Schrodinger (United States)

Joseph P. Dinnocenzo

University of Rochester

Cooperative Institutions

Kodak (United States)

Carestream (United States)

University of Rochester

Kodak (France)

Eastman Chemical Company (United States)

Eastman Chemical Company (Germany)

Arizona State University

California Institute of Technology

Massachusetts Institute of Technology

University at Buffalo, State University of New York

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46.4: OLEDs Containing an Emissive Dinuclear Copper(I) Dopant

SID Symposium Digest of Technical Papers (2009)

Joseph C. Deaton Denis Y. Kondakov Ralph H. Young Thomas D. Pawlik Jonas C. Peters

Abstract A dinuclear copper(I) complex having high luminescence quantum yield was doped into vapor‐deposited OLEDs. The reduction potentials of the host materials correlated with whether the molecular emission or exciplex emission was obtained. The maximum external quantum efficiency obtained for this green emissive dopant was 16%. Device characteristics were analyzed by cyclic voltammetry and photoluminescence.

Quantum yield

Quantum Efficiency

Excimer

10.1889/1.3256878

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Citations (2)

Integer charge transfer states in organic light-emitting diodes: Optical detection of hole carriers at the anode∣organic interface

Journal of Applied Physics (2011)

Alfred P. Marchetti K. E. Sassin Ralph H. Young Lewis J. Rothberg Denis Y. Kondakov

Hole carriers that reside at the anode∣hole-transport-layer (HTL) interface, creating a dipole layer, have been observed in organic light-emitting diode (OLED) and model devices using charge modulation spectroscopic techniques. These interfacial carriers have been observed with various HTL materials and several anode compositions at voltages such that the HTL is reverse-biased. The cation density at an ITO∣CFx∣NPB interface is estimated to be approximately 1×1013/cm2, or approximately 10% of a molecular layer. [NPB is 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl. CFx is a fluorocarbon polymer.] The cations represent the integer charge-transfer states whose presence has been inferred from ultraviolet photoelectron spectroscopy studies of various conductor∣organic interfaces. Anions of an organic hole-injecting material, 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN) were also observed. Conditions near the injecting contacts often determine the electric field profile and drive voltage of an OLED. Elucidation of these conditions is important to a complete understanding and detailed modeling of OLED operation.

Charge carrier

Organic semiconductor

Electron Mobility

Ultraviolet photoelectron spectroscopy

10.1063/1.3525592

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Citations (17)

Optical spectra of a planar aggregate and of a lamellar crystal containing it: How are they related?

The Journal of Chemical Physics (1989)

Ralph H. Young Alfred P. Marchetti E. Irene Newhouse

A simple theory is developed to relate the optical absorption spectrum of a two-dimensional dye aggregate, either dispersed in a transparent matrix or deposited on a transparent substrate, to the spectra of a crystal that consists of a stack of such aggregate layers. Spectral data can then provide evidence on whether the structure of such an aggregate is similar to that of a layer in the crystal. A thiapyrylium dye aggregate dispersed in a polymer film is treated as an example.

Crystal (programming language)

J-aggregate

Matrix (chemical analysis)

10.1063/1.457528

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Citations (1)

Trap-free space-charge-limited current: Analytical solution for an arbitrary mobility law

Philosophical Magazine Letters (1994)

Ralph H. Young

Abstract An elementary analytical expression is provided for the current-voltage characteristic of a unipolar trap-free space-charge-limited current with an arbitrary mobility law. Explicit expressions are provided for the Poole-Frenkel case.

Trap (plumbing)

10.1080/09500839408240995

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Citations (13)

Electronic hopping velocities that decrease as the electric field strength increases

Physical Review Letters (1994)

Ralph H. Young N. Geoffrey Rule

Two molecularly doped polymer systems have been found in which the drift velocity of holes at high field strength (E) is a decreasing function of E: Molecules containing multiple electron-donor moieties dissolved at low concentration in an amorphous polymer. The most likely explanation involves geometric disorder and hopping sites that are most readily escaped by hopping against the field direction.

Field strength

Electron Mobility

10.1103/physrevlett.72.388

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Citations (32)

Photophysical Properties of the Seriesfac-andmer-(1-Phenylisoquinolinato-N^∧C^2′)_x(2-phenylpyridinato-N^∧C^2′)_3−xIridium(III) (x= 1−3)

Inorganic Chemistry (2010)

Joseph C. Deaton Ralph H. Young Jerome R. Lenhard Manju Rajeswaran Shouquan Huo

The photophysical properties of tris-cyclometalated iridium(III) complexes have been probed by chemical and geometric variation through the series fac- and mer-Ir(piq)x(ppy)3−x (x = 1−3; piq = 1-phenylisoquinolinato-N∧C2′, ppy = 2-phenylpyridinato-N∧C2′). The phosphorescent decays were recorded in solution at 295 K and in polymer films from 2 to 295 K. In the heteroleptic complexes, emission occurs based solely on the piq ligand(s), at least by the nanosecond time scale, as its excited states are the lowest energy. Because fac-Ir(piq)3 and fac-Ir(ppy)3 possess practically the same oxidation potential, comparison of photophysical properties through the series fac-Ir(piq)x(ppy)3−x (x = 1−3) revealed the effects of having one, two, or three emissive piq ligands with no confounding effects from differences in electron withdrawing or donating properties between the spectator ppy ligands and the piq ligands. Effects of placement of piq ligands in different coordination geometries were elucidated by comparisons to the mer series.

10.1021/ic1002594

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Citations (74)

46.3: Role of Chemical Transformations of Hole Transport Materials in Operational Degradation of the Current Generation of Highly Efficient Fluorescent OLEDs

SID Symposium Digest of Technical Papers (2009)

Denis Y. Kondakov Ralph H. Young

Abstract We show that the representative hole transport material NPB undergoes significant chemical transformation in operating highly efficient fluorescent OLEDs. The extent and location of the chemical degradation are qualitatively and quantitatively consistent with the hypothesis of its dominant role in the operational degradation mechanism. Effects of dopant and transport materials are also evaluated.

Degradation

Chemical transformation

10.1889/1.3256877

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Citations (5)

Investigation of Organic-Organic Interfaces by Time-Resolved Photocurrent, Electrochemical, And Photoemission Techniques

MRS Proceedings (1997)

Liang‐Bih Lin M. G. Mason Ralph H. Young D. E. Schildkraut P. M. Borsenberger

Photocurrent

Biphenyl

Organic semiconductor

10.1557/proc-488-689

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Citations (3)

DYNAMICS OF PHOTOINDUCED ELECTRON TRANSFER IN SOLUTION

Elsevier eBooks (1991)

Ian R. Gould Ralph H. Young Samir Farid

Dynamics

Photoinduced electron transfer

10.1016/b978-0-444-88878-5.50010-1

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Citations (12)

CCDC 764332: Experimental Crystal Structure Determination

The Cambridge Structural Database (2011)

Joseph C. Deaton Ralph H. Young Jerome R. Lenhard M. Rajeswaran Shouquan Huo

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

10.5517/cctnbwn

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