A Novel Mitigation Mechanism for Photo-Induced Trapping in an Anthradithiophene Derivative Using Additives

© 2020 Wiley-VCH GmbH A novel trap mitigation mechanism using molecular additives, which relieves a characteristic early turn-on voltage in a high-mobility p-type acene-based small-molecule organic semiconductor, when processed from hydrous solvents, is reported. The early turn-on voltage is attributed to photo-induced trapping, and additive incorporation is found to be very effective in suppressing this effect. Remarkably, the molecular additive does not disturb the charge transport properties of the small-molecule semiconductor, but rather intercalates in the crystal structure. This novel technique allows for the solution-processing of small molecular semiconductors from hydrous solvents, greatly simplifying manufacturing processes for large-area electronics. Along with various electric and spectroscopic characterization techniques, simulations have given a deeper insight into the trap mitigation effect induced by the additive

A Computation in a Cellular Automaton Collider Rule 110

A cellular automaton collider is a finite state machine build of rings of one-dimensional cellular automata. We show how a computation can be performed on the collider by exploiting interactions between gliders (particles, localisations). The constructions proposed are based on universality of elementary cellular automaton rule 110, cyclic tag systems, supercolliders, and computing on rings.Comment: 39 pages, 32 figures, 3 table

UV-induced electrical and optical changes in PVC blends

2-Chloro-polyaniline (2-Cl-PANI) in its non-conducting (emeraldine base, EB) form, prepared by a chemical route, was dissolved together with poly-(vinylchloride) (PVC) in THF for casting into thin (10-50 μm) films. Upon exposure to UV radiation, the electrical conductivity of these films increased by more than 4 orders of magnitude (from 10-6 to 10-2 S/cm). This is attributed to the dehydrochlorination of PVC by exposure to energetic photons and subsequent doping of 2-Cl-PANI (i.e. conversion to emeraldine salt, ES) by in situ created HCl. The doped films could be returned to their undoped form by exposure to NH3 vapours. The UV-induced doping/NH3 undoping cycles could be repeated several times. Various spectroscopic techniques were employed to follow the changes in the films upon exposure to UV radiation. The same photo-dehydrochlorination process has also been utilized for optical and/or lithographic purposes by preparing PVC blends containing methyl violet, and acid-base indicator dye. The photo-dehydrochlorination can be effectively sensitized by incorporating hydroquinone into the PVC blends containing methyl violet

Quantum-confinement effects on the ordering of the lowest-lying excited states in conjugated chains

The symmetrized density-matrix renormalization-group approach is applied within the extended Hubbard-Peierls model (with parameters U/t, V/t, and bond alternation delta) to study the ordering of the lowest one-photon (1(1)B(u)(-)) and two-photon (2(1)A(g)(+)) states in one-dimensional conjugated systems with chain lengths N up to N = 80 sites. Three different types of crossovers are studied, as a function of U/t, delta, and N. The ''U crossover'' emphasizes the larger ionic character of the 2A(g) state compared to the lowest triplet excitation. The ''delta crossover'' shows strong dependence on both N and U/t. the ''N crossover'' illustrates the more localized nature of the 2A(g) excitation relative to the 1B(u) excitation at intermediate correlation strengths

Understanding charge transport in donor/acceptor blends from large-scale device simulations based on experimental film morphologies

Bulk-heterojunction organic photovoltaic (OPV) devices consist of active layers made of electron donor/acceptor blends. Understanding the impact of the blend morphologies on the optoelectronic processes occurring in OPVs is of crucial importance for a complete description of the device physics and the achievement of higher device efficiencies. However, high-resolution morphology data are scarce and theoretical methodologies with the appropriate level of details and affordable computational costs are underdeveloped. As a result, previous device modeling often had to rely on artificially generated blend morphologies, which do not represent those in actual devices. Here, by considering three-dimensional donor/acceptor blend morphologies recently determined via electron tomography, we have established an original approach that allows us to perform device-scale simulations of charge transport in actual blend morphologies. The current characteristics, carrier distributions, and internal current pathways and densities are determined and compared to those based on the artificial morphologies often used in OPV-related studies

Understanding charge transport in donor/acceptor blends from large-scale device simulations based on experimental film morphologies

Bulk-heterojunction organic photovoltaic (OPV) devices consist of active layers made of electron donor/acceptor blends. Understanding the impact of the blend morphologies on the optoelectronic processes occurring in OPVs is of crucial importance for a complete description of the device physics and the achievement of higher device efficiencies. However, high-resolution morphology data are scarce and theoretical methodologies with the appropriate level of details and affordable computational costs are underdeveloped. As a result, previous device modeling often had to rely on artificially generated blend morphologies, which do not represent those in actual devices. Here, by considering three-dimensional donor/acceptor blend morphologies recently determined via electron tomography, we have established an original approach that allows us to perform device-scale simulations of charge transport in actual blend morphologies. The current characteristics, carrier distributions, and internal current pathways and densities are determined and compared to those based on the artificial morphologies often used in OPV-related studies