Photoemission spectroscopy is commonly applied to study the band structure of solids by measuring kinetic energy versus angular distribution photoemitted electrons. Here, we apply this experimental technique characterize discrete orbitals large pi-conjugated molecules. By photoemission intensity from a constant initial-state over hemispherical region, generate reciprocal space maps emitting orbital density. We demonstrate that real-space electron molecular in both crystalline pentacene film...

Abstract Here the influence of annealing on operational efficiency all‐polymer solar cells based blends polymers poly(3‐hexylthiophene) (P3HT) and poly((9,9‐dioctylfluorene)‐2,7‐diyl‐alt‐[4,7‐bis(3‐hexylthiophen‐5‐yl)‐2,1,3‐benzothiadiazole]‐2′,2″‐diyl) (F8TBT) is investigated. Annealing completed devices found to result in an increase power conversion from 0.14 1.20%, while films prior top electrode deposition increases device only 0.19% due a lowering open‐circuit voltage short‐circuit...

The high crystallinity of many inorganic materials allows their band structures to be determined through angle-resolved photoemission spectroscopy (ARPES). Similar studies conjugated organic molecules interest in optoelectronics are often hampered by difficulties growing well-ordered and well-oriented crystals or films. We have grown crystalline films uniaxially oriented sexiphenyl obtained ARPES data. Supported density-functional calculations, we show that, the direction parallel principal...

We study the interface of an organic monolayer with a metallic surface, i.e., PTCDA (3,4,9,10-perylene-tetracarboxylic-dianhydride) on Ag(110), by means angle-resolved photoemission spectroscopy (ARPES) and ab initio electronic structure calculations. present tomographic method that uses energy momentum dependence ARPES data to deconvolute spectra into individual orbital contributions beyond limits resolution. This provides orbital-by-orbital characterization large adsorbate systems without...

What do energy level alignments at metal-organic interfaces reveal about the metal-molecule bonding strength? Is it permissible to take vertical adsorption heights as indicators of strengths? In this paper we analyse 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on three canonical low index Ag surfaces provide exemplary answers these questions. Specifically, employ angular resolved photoemission spectroscopy for a systematic study two uppermost frontier states in ordered...

It is becoming accepted that ultrathin dielectric layers on metals are not merely passive decoupling layers, but can actively influence orbital energy level alignment and charge transfer at interfaces. As such, they be important in applications ranging from catalysis to organic electronics. However, the details molecular still under debate. In this study, we present a comprehensive analysis of phenomenon promoted by interlayer with comparative study pentacene adsorbed Ag(001) without an MgO...

The complete phase diagram of In-induced surface reconstructions on Si(111) surfaces has been mapped by scanning tunneling microscopy (STM) and spectroscopy (STS). results illustrate the transition from low-coverage semiconducting via semimetallic phases to metallic at monolayer coverages. Electronic effects in STM imaging process preclude a straightforward interpretation data terms structure models for intermediate coverages, but higher-coverage topographic analysis is possible detailed are...

Abstract Knowledge of the structure and orientation organic molecules on solid surfaces is fundamental relevance in many diverse areas physical sciences, ranging from heterogeneous catalysis to tribology polymer interface science. For example, local a molecule metal surface decisive importance for determining subsequent reaction paths, or science composite materials adhesion between layers inorganic substrate direct consequence chemical bonding functional groups atoms at interface. Key...

Recently, it has been shown that experimental data from angle-resolved photoemission spectroscopy on oriented molecular films can be utilized to retrieve real-space images of orbitals in two dimensions. Here, we extend this orbital tomography technique by performing initial state scans as a function photon energy the example brickwall monolayer 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) Ag(110). The overall dependence photocurrent well accounted for assuming plane wave final...

Significance In quantum mechanics, the electrons in a molecule are described by mathematical object termed wave function or molecular orbital. This determines chemical and physical properties of matter consequently there has been much interest measuring orbitals, despite fact that strictly speaking they not quantum-mechanical observables. We show how amplitude phase orbitals can be measured good agreement with functions from ab initio calculations. Not only do such measurements allow complex...

The energy positions of frontier orbitals in organic electronic materials are often studied experimentally by (inverse) photoemission spectroscopy and theoretically within density functional theory. However, standard exchange-correlation functionals result too small fundamental gaps, may lead to wrong orbital ordering, do not capture polarization-induced gap renormalization. Here we examine these issues a strategy for overcoming them studying the gas phase bulk structure molecule...

The growth of thin vanadium oxide films on Pd(111) prepared by reactive evaporation in an oxygen atmosphere has been studied scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and ab initio density-functional-theory (DFT) calculations. Two-dimensional (2D) is observed at coverages below one-half a monolayer (ML), displaying both random island step-flow modes. Above the critical coverage 0.5 ML, three-dimensional initiated. morphology low-coverage 2D phase depends...

In the growth process of ultrathin films vanadium oxides on Pd(111), a sequence novel oxide phases with layer-dependent structures and oscillating oxidation states has been detected experimentally understood theoretically. These are interface mediated metastable respect to further growth. Transformation into stable configuration occurs beyond critical thickness, where energetics combined kinetic limitations determine multilayer structure.

With angle resolved photoemission experiments and \emph{ab-initio} electronic structure calculations, the pentacene monolayers on Ag(110) Cu(110) are compared contrasted allowing molecular orientation an unambiguous assignment of emissions to specific orbitals be made. On Ag(110), remain essentially isolated-molecule like, while strong substrate-enhanced dispersion orbital modification observed upon adsorption Cu(110). We show how intensity extended systems can simulated that it behaves like...

The growth and structure of ultrathin vanadium oxide films on Rh(111) has been studied by scanning tunneling microscopy, low-energy electron diffraction, high-resolution x-ray photoelectron spectroscopy, energy-loss ab initio density-functional-theory calculations. For submonolayer coverages $[\ensuremath{\Theta}<0.6\mathrm{MLE}$ (monolayer equivalents)], depending the preparation route (reactive evaporation vs postoxidation), two well-ordered V-oxide phases with...

Highly crystalline organic heteroepitaxial layers with controlled molecular orientations and morphologies are one of the keys for optimum device performance. With studies orientation, structure, morphology, we have investigated ability oriented films to act as substrate templates growth a second layer. Depending on orientation in sexiphenyl substrate, sexithiophene nanostructures either pyramidal or needlelike near vertical parallel orientations, respectively, grow.

Controlling the molecular growth of organic semiconductors is an important issue to optimize performance devices. Conjugated molecules, used as building blocks, have anisotropic shape and also physical properties like charge transport or luminescence. The main challenge grow highly crystalline layers with molecules defined orientation. higher crystallinity, closer these reach their full intrinsic potential, while orientation determines film. Herein we show that can be steered by surface...