Magnetic properties of a single vacancy in graphene is relevant and still much discussed problem. The experimental results point to clearly detectable magnetic defect state at the Fermi energy, while calculations based on density functional theory (DFT) yield widely varying for moment, range $\ensuremath{\mu}=1.04--2.0\phantom{\rule{4pt}{0ex}}{\ensuremath{\mu}}_{B}$. We present multitool ab initio theoretical study same defect, using two simulation protocols crystal (cluster periodic...

The mechanism and the nature of species formed by molecular doping model polymer poly(3-hexylthiophene) (P3HT) in its regioregular (rre-) regiorandom (rra-) forms solution are investigated for three different dopants: prototypical π-electron acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), strong Lewis acid tris(pentafluorophenyl)borane (BCF), strongly oxidizing complex molybdenum tris[1-(methoxycarbonyl)-2-(trifluoromethyl)ethane-1,2-dithiolene] (Mo(tfd-CO2Me)3). In a...

Experimental Raman spectra of molecularly doped P3HT thin films are combined with first-principles calculations on oligomer models to understand and identify the fingerprints for polarons bipolarons in P3HT.

We investigate from the first-principles many-body theory role of donor conjugation length in doped organic semiconductors forming charge-transfer complexes (CTCs) exhibiting partial charge transfer. consider oligothiophenes (nT) with an even number rings, ranging four to ten, by strong acceptor, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ). The decrease electronic gaps upon increasing nT size is driven reduction ionization energy electron affinity remaining almost...

For molecularly doped poly(3-hexyl-thiophene) solvated individual chains can be unambiguously differentiated from aggregated ones by diagnostic polaron absorption.

Two-dimensional transition metal dichalcogenides (2D TMDCs) can be combined with organic semiconductors to form hybrid van der Waals heterostructures.

Abstract The development of advanced experimental and theoretical methods for the characterization excitations in materials enables revisiting established concepts that are sometimes misleadingly transferred from one field to another without necessary disclaimers. This is precisely situation occurs excitons organic materials: different states matter peculiarities related their structural arrangements environment may substantially alter nature photo-induced excited compared inorganic...

Local interface structures affect the<italic>ab initio</italic>modelling of the electronic and optical properties doped organic semiconductors.

Organic charge transfer complexes (CTCs) with near-infrared absorption received growing interest in the past years, but details of their photophysics, especially thin films, remain largely unknown. We combined experimental and computational methods to thoroughly investigate compare CTCs formed by tetracene 2,2′-(perfluoronaphthalene-2,6-diylidene)dimalononitrile 2,3,5,6-tetrafluoro-7,7,8,8,-tetracyanoquinodimethane, respectively. Using ultrafast transient spectroscopy, photophysics these...

The design of low-dimensional organic-inorganic interfaces for the next generation opto-electronic applications requires in-depth understanding microscopic mechanisms ruling electronic interactions in these systems. In this work, we present a first-principles study based on density-functional theory inspecting structural, energetic, and properties five molecular donors acceptors adsorbed freestanding hexagonal boron nitride (hBN) molybdenum disulfide (MoS2) monolayers. All considered are...

Solvent-solute interactions in precursor solutions of lead halide perovskites (LHP) critically impact the quality solution-processed materials, as they to formation a variety poly-iodoplumbates that act building blocks for LHP. The [PbI$_{2+n}$]$^{n-}$ complexes is often expected diluted while coordination occurring at high concentrations not well understood yet. In combined \textit{ab initio} and experimental work, we demonstrate optical spectra quasi-one-dimensional iodoplumbate...

Abstract Modeling the electronic and optical properties of organic semiconductors remains a challenge for theory, despite remarkable progress achieved in last three decades. The complexity these systems, including structural (dis)order still debated doping mechanisms, has been engaging theorists with different background. Regardless common interest across various communities active this field, efforts have not led so far to truly interdisciplinary research. In attempt move further direction,...

Abstract Heterostructures obtained by combining two-dimensional (2D) sheets are widely investigated as a platform for designing new materials with customised characteristics. Transition metal dichalcogenides (TMDCs) often combined hexagonal boron nitride (hBN) to enhance their excitonic resonances. However, little is known about how stacking affects excitons and plasmons in TMDCs or mutual interactions. Here, we combine momentum-resolved electron energy-loss spectroscopy first-principles...

Real-time time-dependent density functional theory, in conjunction with the Ehrenfest molecular dynamics scheme, is becoming a popular methodology to investigate ultrafast phenomena on nanoscale. Thanks recent developments, it also possible explicitly include simulations laser pulse, thereby accessing transient excitation regime. However, complexity entailed these calculations calls for in-depth analysis of accessible and yet approximate (either "dressed" or "bare") quantities order evaluate...

Due to their favorable properties and high porosity, zeolitic imidazolate frameworks (ZIFs) have recently received much limelight for key technologies such as energy storage, optoelectronics, sensorics, catalysis. Despite widespread interest in these materials, fundamental questions regarding the zinc coordination environment remain poorly understood. By focusing on zinc(II)2-methylimidazolate (ZIF-8) its tetrahedrally coordinated analogues with Br-, Cl-, H-substitution 2-ring position, we...

Electronic and optical properties of doped organic semiconductors are dominated by local interactions between donor acceptor molecules. However, when such systems in crystalline form, long-range order competes against short-range couplings. In a first-principles study on three experimentally resolved bulk structures quaterthiophene (fluorinated) tetracyanoquinodimethane, we demonstrate the crucial role donor/acceptor co-crystals. The band investigated materials exhibit direct band-gaps...

Singlet fission (SF), the photophysical process in which one singlet exciton is transformed into two triplets, depends inter alia on coupling of electronic states. Here, we use fluorination and resulting changes partial charge distribution across chromophore backbone as a particularly powerful tool to control this parameter pentacene. We find that introduction permanent dipole moment leads an enhanced Frenkel transfer states increased SF rate probed using ultrafast transient absorption...

The interactions between organic donor and acceptor molecules the related charge transfer (CT) effects are of great interest in optoelectronics. Here, we present a comprehensive investigation cocrystal formation weakly interacting semiconductor mixtures. As model system, choose dinaphthothienothiophene (DNTT) as molecule two different perylene diimide derivatives (PTCDI-C8-CN2 PDIF-CN2) acceptors, which differ fluorination side chains imide position. Experimentally, both systems show small...

The coherent coupling between electronic excitations and vibrational modes of molecules largely affects the optical charge transport properties organic semiconductors molecular solids. To analyze these couplings by means ultrafast spectroscopy, highly ordered crystalline films with large domains are particularly suitable because can be addressed individually, hence allowing azimuthal polarization-resolved measurements. Impressive examples this thin perfluoropentacene (PFP) molecules, which...

Lewis acids like tris(pentafluorophenyl)borane (BCF) offer promising routes for efficient p-doping of organic semiconductors. The intriguing experimental results achieved so far call a deeper understanding the underlying doping mechanisms. In first-principles work, based on state-of-the-art density-functional theory and many-body perturbation theory, we investigate electronic optical properties donor/acceptor complexes formed by quarterthiophene (4T) doped BCF. For reference,...

Abstract While the basal plane of graphene is inert, defects in it are centers chemical activity. An attractive application such towards controlled functionalization with foreign molecules. However, interaction reactive environment, as ambient, decreases efficiency and makes poorly controlled. Here, we report a novel approach to generate, monitor time resolution, functionalize situ without ever exposing them ambient. The generated by an energetic argon plasma their properties monitored using...

Hybrid interfaces formed by inorganic semiconductors and organic molecules are intriguing materials for opto-electronics. Interfacial charge transfer is primarily responsible their peculiar electronic structure optical response. Hence, it essential to gain insight into this fundamental process also beyond the static picture. Ab initio methods based on real-time time-dependent density-functional theory coupled Ehrenfest molecular dynamics scheme ideally suited problem. We investigate a...

The first-principles simulation of the electronic structure organic semiconductors in solution poses a number challenges that are not trivial to address simultaneously. In this work, we investigate effects and mutual interplay solvation, alkylization, doping on structural, electronic, optical properties sexithiophene, representative semiconductor molecule. To end, employ (time-dependent) density functional theory conjunction with polarizable-continuum model. We find torsion between adjacent...

The ultrafast dynamics of charge carriers in organic donor–acceptor interfaces are primary importance to understanding the fundamental properties these systems. In this work, we focus on a charge-transfer complex formed by quaterthiophene p-doped tetrafluoro-tetracyanoquinodimethane and investigate electron vibronic interactions also at finite temperatures applying femtosecond pulse resonance with two lowest energy excitations system perpendicular parallel polarization respect interface....

Charge-transfer excitons (CTX) at organic donor/acceptor interfaces are considered important intermediates for charge separation in photovoltaic devices. Crystalline model systems provide microscopic insights into the nature of such states as they enable structure-property investigations. Here, we use angular-resolved UV/Vis absorption spectroscopy to characterize CTX crystalline pentacene:perfluoro-pentacene (PEN:PFP) films allowing determine polarization this state. This analysis is...