Fast and highly efficient intramolecular singlet exciton fission in a pentacene dimer, consisting of two covalently attached, nearly orthogonal units is reported. Fission to triplet excitons from this ground state geometry occurs within 1 ps isolated molecules solution dispersed solid matrices. The process exhibits sensitivity environmental polarity competes with geometric relaxation the state, while subsequent decay strongly dependent on conformational freedom. near arrangement unlike any...

We implement a simple, continuous, analytical model for exciton hopping in an energetically disordered molecular landscape. The is parameterized against atomistic and lattice Monte Carlo simulations based on quantum-chemical calculations. It captures the essential physics of diffusion media at different temperatures yields universal scaling law length with dimensionless disorder parameter given by ratio energetic width to thermal energy.

We developed an analytical model to describe hopping transport in organic semiconductors including both energetic disorder and polaronic contributions due geometric relaxation. The is based on a Marcus jump rate terms of the small-polaron concept with Gaussian disorder, it premised upon generalized effective medium approach yet avoids shortcomings involved energy or percolation concepts. It superior our previous treatment [Phys. Rev. B 76, 045210 (2007)] since applicable at arbitrary polaron...

Small-molecule donor materials can be prepared in one step using simple condensation chemistry.

While it has been argued that field‐dependent geminate pair recombination (GR) is important, this process often disregarded when analyzing the kinetics in bulk heterojunction organic solar cells (OSCs). To differentiate between contributions of GR and nongeminate (NGR) authors study bilayer OSCs using either a PCDTBT‐type polymer layer with thickness from 14 to 66 nm or 60 thick p‐DTS(FBTTh 2 ) as donor material C acceptor. The measure JV ‐characteristics function intensity...

This paper presents a detailed spectroscopic investigation of luminescence properties 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) and N,N,N′,N′-tetraphenylbenzidine (TAD) in solutions neat films. These compounds are compared to their derivatives CDBP TDAD that contain methyl groups the 2 2′ position biphenyl core. We find whereas steric twisting leads high triplet energy about 3.0 3.1 eV, respectively, these also tend form excimers film, contrast CBP TAD. By comparison with N-phenylcarbazole...

We demonstrate that efficient and nearly field-independent charge separation of electron-hole pairs in organic planar heterojunction solar cells can be described by an incoherent hopping mechanism. Using kinetic Monte Carlo simulations include the effect on-chain delocalization as well entropic contributions, we simulate dissociation charge-transfer state polymer-fullerene bilayer cells. The model further explains experimental results almost field independent bilayers molecular systems with...

Abstract The high efficiencies reported for organic solar cells and an almost negligible thermal activation measured the photogeneration of charge carriers have called into question whether photoinduced interfacial transfer states are bound by a significant coulomb attraction, how this can be reconciled with very low energies. Here, is addressed in combined experimental theoretical approach. binding energy charge‐transfer state blend MeLPPP:PCBM determined using resolved electrochemical...

The potential of dendrimers exhibiting thermally activated delayed fluorescence (TADF) as emitters in solution-processed organic light-emitting diodes (OLEDs) has to date not yet been realized. This part is due a poor understanding the structure-property relationship where reports detailed photophysical characterization and mechanism studies are lacking. In this report, using absorption solvatochromic photoluminescence solution, origin character lowest excited electronic states with multiple...

We present a theoretical study of charge transport in disordered semiconducting polymers that relates the mobility to chemical structure and physical morphology novel multiscale approach. Our studies, focusing on poly(9,9-dioctylfluorene) (PFO), show is dominated by pathways with highest interchain charge-transfer rates. also find disorder not always detrimental transport. good agreement experimental time-of-flight data highly aligned PFO films.

We have performed classical molecular dynamics simulations and quantum-chemical calculations on crystals of anthracene perfluoropentacene. Our goal is to characterize the amplitudes room-temperature displacements corresponding thermal fluctuations in electronic transfer integrals, which constitute a key parameter for charge transport organic semiconductors. show that lead Gaussian-like distributions integrals centered around values obtained equilibrium crystal geometry. The calculated been...

We investigate the combined influence of energetic disorder and delocalization on electron-hole charge-transfer state separation efficiency in donor-acceptor organic photovoltaic systems using an analytical hopping model Monte Carlo calculations, coupled with effective mass model. Whereas increases yield at intermediate low electric fields for low-efficiency blends strongly localized carriers, we find that it reduces dramatically fill factors power conversion efficiencies high-efficiency...

A Monte-Carlo approach based on hopping rates computed from quantum-chemical calculations is applied to model the energy diffusion dynamics in a polyindenofluorene conjugated polymer predetermined chain morphology. While predicts faster time-dependent evolution than that seen by site-selective experiments and yields length an order of magnitude larger typical experimental values, we show these discrepancies can be corrected introducing low concentration traps transport simulations....

In order to unravel the intricate interplay between disorder effects, molecular reorganization, and charge carrier localization, a comprehensive study was conducted on hole transport in series of conjugated alternating phenanthrene indenofluorene copolymers. Each polymer contained one further comonomer comprising monoamines, diamines, or amine-free structures, whose influence electronic, optical, properties studied. The covered wide range highest occupied orbital (HOMO) energies as...

In disordered organic semiconductors, excited states and charges move by hopping in an inhomogeneously broadened density of states, thereby relaxing energetically ("spectral diffusion"). At low temperatures, transport can become kinetically frustrated consequently dispersive. Experimentally, this is observed predominantly for triplet excitations charges, has not been reported singlet excitations. We have addressed the origin phenomenon simulating temperature dependent spectral diffusion...

We have investigated how electronic excitations that couple via short-range interaction, i.e., triplet and charge carriers, move in a disordered organic semiconductor. In this systematic study, we paid special emphasis to the transition from quasi-equilibrium nonequilibrium transport as temperature is lowered 300 10 K. As method, used Monte Carlo simulations employing both Marcus well Miller–Abrahams (MA) rates. The simulation parameters are degree of static energetic disorder, geometric...

Poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT) is a copolymer composed of alternating thiophene–benzothiadiazole–thiophene (TBT) and carbazole (Cbz) repeat units widely used for stable organic photovoltaics. However, the solubility PCDTBT limited, which decreases polymer yield makes synthesis purification tedious. Here, we introduce strategy to increase both luminescence by statistical incorporation additional hexyl side chains at TBT...

The synthesis of stable blue TADF emitters and the corresponding matrix materials is one biggest challenges in development novel OLED materials. We present six bipolar host based on triazine as an acceptor two types donors, namely, carbazole, acridine. Using a tool box approach, chemical structure changed systematic way. Both carbazole acridine donor are connected to via para- or meta-linked phenyl ring linked directly each other. photophysics has been investigated detail by absorption-,...

Abstract In an endeavor to understand why the dissociation of charge‐transfer (CT) states in a PM6:Y6 solar‐cell is not thermally activated process, measurements energy‐resolved impedance as well intrinsic photoconduction are employed. This study determines density distributions pertinent HOMO and LUMO obtains Coulomb binding energy ( E b , CT ) ≈150 meV. 250 meV lower than value expected for pair localized charges with 1 nm separation. The reason that hole delocalized polymer electron...

A great deal of interest has recently focused on host-guest systems consisting one-dimensional collinear arrays conjugated molecules encapsulated in the channels organic or inorganic matrices. Such architectures allow for controlled charge and energy migration processes between interacting guest are thus attractive field electronics. In this context, we characterize here at a quantum-chemical level molecular parameters governing transport hopping regime 1D built with different types...

Triplet exciton migration in the anthracene single crystal is modeled using a kinetic Monte Carlo scheme based on fully atomistic hopping rates. These account for coupling of triplet excitations to both intramolecular vibrations and lattice phonons from first principles. Thermal fluctuations site energies excitonic couplings obtained within fragmented excitation difference approach yield diffusion constants quantitative agreement with experiment.

A novel pyrimidine-based host material with a triplet energy of 3.07 eV was synthesized. Sky blue and OLEDs were fabricated, obtaining high external quantum efficiency extremely low roll-off.

We have developed a theoretical platform for modelling temperature-dependent exciton transport in organic materials, using indenofluorene trimers as case study. Our atomistic molecular dynamics simulations confirm the experimentally observed occurrence of liquid crystalline smectic phase at room temperature and predict transition to isotropic between 375 400 K. Strikingly, increased orientational disorder elevated temperatures barely affects ability excitons be transported over large...

Ultrafast intramolecular electronic energy transfer in a conjugated donor-acceptor system is simulated using nonadiabatic excited-state molecular dynamics. After initial site-selective photoexcitation of the donor, transition density localization monitored throughout S2 → S1 internal conversion process, revealing an efficient unidirectional donor acceptor energy-transfer process. Detailed analysis trajectories uncovers several salient features While weak temperature dependence observed...

Photoinduced electronic energy transfer in conjugated donor-acceptor systems is naturally accompanied by intramolecular vibrational redistributions accepting an excess of energy. Herein, we simulate these processes a covalently linked molecular dyad system using nonadiabatic excited state dynamics simulations. We analyze different complementary criteria to systematically identify the subset normal modes that actively participate on donor → acceptor (S2→ S1) relaxation. coordinates terms...