Energetics of metal–organic interfaces: New experiments and assessment of the field

Hwang, Jae-Yeol; Wan, A.; Kahn, Antoine

doi:10.1016/j.mser.2008.12.001

Cited by 606 publications

(655 citation statements)

References 130 publications

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“…The UPS spectra are shown as a function of binding energy with respect to the vacuum level, and the energy edge of the valence band is used to determine the ionization potential of the measured film 55 . The ionization potential of pentacene was measured to be 5.05 eV, in agreement with previous measurements 45,46 .…”

Section: Methodssupporting

confidence: 89%

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In situ measurement of exciton energy in hybrid singlet-fission solar cells

et al. 2012

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singlet exciton fission-sensitized solar cells have the potential to exceed the shockley-Queisser limit by generating additional photocurrent from high-energy photons. Pentacene is an organic semiconductor that undergoes efficient singlet fission-the conversion of singlet excitons into pairs of triplets. However, the pentacene triplet is non-emissive, and uncertainty regarding its energy has hindered device design. Here we present an in situ measurement of the pentacene triplet energy by fabricating a series of bilayer solar cells with infrared-absorbing nanocrystals of varying bandgaps. We show that the pentacene triplet energy is at least 0.85 eV and at most 1.00 eV in operating devices. our devices generate photocurrent from triplets, and achieve external quantum efficiencies up to 80%, and power conversion efficiencies of 4.7%. This establishes the general use of nanocrystal size series to measure the energy of non-emissive excited states, and suggests that fission-sensitized solar cells are a favourable candidate for third-generation photovoltaics.

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Section: Methodssupporting

confidence: 89%

“…This indicates that quantum confinement affects the conduction band state (1S e ) much more strongly than the valence band state (1S h ) 44 . We also found that the energy of the highest occupied molecular orbital in pentacene is − 5.05 ± 0.05 eV, in accordance with earlier measurements 45,46 .…”

Section: Pbse Nanocrystalssupporting

confidence: 92%

In situ measurement of exciton energy in hybrid singlet-fission solar cells

et al. 2012

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“…[128][129][130] Alkyl monolayers appear not to change the dipole much beyond the effect of the SiÀC bond dipole, as noted above. DFT calculations show that most of the potential change occurs over the SiÀC bond with some extra contribution from the terminal methyl group.…”

Section: Molecular Dipolesupporting

confidence: 56%

Molecules on Si: Electronics with Chemistry

et al. 2009

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Basic scientific interest in using a semiconducting electrode in molecule‐based electronics arises from the rich electrostatic landscape presented by semiconductor interfaces. Technological interest rests on the promise that combining existing semiconductor (primarily Si) electronics with (mostly organic) molecules will result in a whole that is larger than the sum of its parts. Such a hybrid approach appears presently particularly relevant for sensors and photovoltaics. Semiconductors, especially Si, present an important experimental test‐bed for assessing electronic transport behavior of molecules, because they allow varying the critical interface energetics without, to a first approximation, altering the interfacial chemistry. To investigate semiconductor‐molecule electronics we need reproducible, high‐yield preparations of samples that allow reliable and reproducible data collection. Only in that way can we explore how the molecule/electrode interfaces affect or even dictate charge transport, which may then provide a basis for models with predictive power.To consider these issues and questions we will, in this Progress Report, review junctions based on direct bonding of molecules to oxide‐free Si. describe the possible charge transport mechanisms across such interfaces and evaluate in how far they can be quantified. investigate to what extent imperfections in the monolayer are important for transport across the monolayer. revisit the concept of energy levels in such hybrid systems.

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“…4 Electronic structure at interfaces 4.1 Molecule adsorption on ferromagnetic metals Due to the importance of charge transfer across metal/OSC interfaces in field effect transistors and organic light emitting devices (OLEDs) there is a large body of experimental work that has been cited in several excellent review articles [17,18]. However, there is much less known about the electronic structure at FM/OSC interfaces.…”

mentioning

confidence: 99%

The role of interfaces in organic spin valves revealed through spectroscopic and transport measurements

Drew

Szulczewski

Nuccio

et al. 2011

Physica Status Solidi (b)

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Interfaces between dissimilar materials are critical to the performance of many electronic devices. In electrical devices where the active transport is through an organic semiconductor (OSC) layer there are metallic electrodes to supply and remove the charge carriers. At metal/molecule and molecule/metal interfaces the electrical contact is usually not Ohmic. As a result, in most metal-organic semiconductors-metal devices charge injection is mainly governed by tunneling across the barriers. When the metal electrodes are ferromagnetic the density of occupied and unoccupied electronic states is spindependent, which presents further subtleties to the electron transfer. In this article we summarize some of the important experimental results that have advanced our understanding of spin-polarized electron transfer across ferromagnetic metal (FM)/OSC interfaces. In particular, we highlight key spectroscopic studies that have revealed insights into the nature of the electronic structure between OSCs and FMs, in particular between Alq 3 and Co and Fe surfaces. We discuss the relationship between energy level diagrams for these systems and transport measurements made on spin-valve devices.

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Energetics of metal–organic interfaces: New experiments and assessment of the field

Cited by 606 publications

References 130 publications

In situ measurement of exciton energy in hybrid singlet-fission solar cells

In situ measurement of exciton energy in hybrid singlet-fission solar cells

Molecules on Si: Electronics with Chemistry

The role of interfaces in organic spin valves revealed through spectroscopic and transport measurements

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