Dibenzo[ f,h]furazano[3,4- b]quinoxalines: Synthesis by Intramolecular Cyclization through Direct Transition Metal-Free C-H Functionalization and Electrochemical, Photophysical, and Charge Mobility Characterization

Herein, we describe the synthesis of unsymmetrically substituted dibenzo[f,h]furazano[3,4-b]quinoxalines by intramolecular cyclization through direct transition metal-free C-H functionalization. The electrochemical and photophysical properties for several polycycles have been measured. In thin films of the dibenzo[f,h]furazano[3,4-b]quinoxalines, hole mobility is in the order of 10-4 cm2 V-1 s-1. The results show that the HOMO and LUMO energy levels are appropriate for using the compounds as hole-transport materials in thin-film devices, in particular, organic and perovskite solar cells. Copyright © 2020 American Chemical Society.Russian Foundation for Basic Research, RFBR: 18-33-00103-mol_aRussian Science Foundation, RSF: 18-13-00409The research was financially supported by the Russian Science Foundation (project no. 18-13-00409). Y.A.K would like to acknowledge the financial support for the part of the synthetic section from the Russian Foundation for Basic Research (research project no. 18-33-00103-mol_a). The authors are grateful to Grigory A. Kim for carrying out the DFT calculations, which were performed by using “Uran” supercomputer of the Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences. NMR experiments were carried out by using equipment of the Center for Joint Use “Spectroscopy and Analysis of Organic Compounds” at the Postovsky Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences

Ion-beam sputtering of NiO hole transporting layers for p-i-n halide perovskite solar cells

Ion-beam sputtering offers significant benefits in terms of deposition uniformity and pinhole-free thin-films without limiting the scalability of the process. In this work, the reactive ion-beam sputtering of nickel oxide has been developed for the hole transporting layer of a p-i-n perovskite solar cells (PCSs). The process is carried out by oxidation of the scattered Ni particles with additional post-treatment annealing regimes. Using deposition rate of 1.2 nm/min allowed growth of very uniform NiO coating with the roughness below 0.5 nm on polished Si wafer (15x15 cm2). We performed a complex investigation of structural, optical, surface and electrical properties of the NiO thin-films. The post-treatment annealing (150-300C) was considered as an essential process for improvement of the optical transparency, decrease of defects concentration and gain of the charge carrier mobility. As result, the annealed ion-beam sputtered NiO films delivered a power conversion efficiency (PCE) up to 20.14%, while device without post-treatment reached the value of 11.84%. The improvement of the output performance originated from an increase of the short-circuit current density (Jsc), open circuit voltage (Voc), shunt and contact properties in the devices. We also demonstrate that the ion-beam sputtering of NiO can be successfully implemented for the fabrication of large area modules (54.5 cm2) and PSCs on a flexible plastic substrate (125 microns)

New Approach to Unsymmetrical 1,3- and 1,4-Diazatriphenylene Derivatives Through Intramolecular Oxidative Cyclodehydrogenation

The research was financially supported by the Russian Science Foundation (Project № 16-13-10435). NMR spectra and elemental analyses were covered by Program of the Ural Branch of the Russian Academy of Sciences (Рroject № 18-3-3-12)

Benzo[ b]selenophene/thieno[3,2- b]indole-Based N,S,Se-Heteroacenes for Hole-Transporting Layers

Two series of new N,S,Se-heteroacenes, namely, 6H-benzo[4′,5′]selenopheno[2′,3′:4,5]thieno[3,2-b]indoles and 12H-benzo[4″,5″]selenopheno[2″,3″:4′,5′]thieno[2′,3′4,5]thieno[3,2-b]indoles, were successfully obtained using an effective strategy based on Fiesselmann thiophene and Fischer indole synthesis. The new molecules exhibit a large optical band gap (2.82 eV < Egopt < 3.23 eV) and their highest occupied molecular orbital (HOMO) energy formed by the plane π-core ranges between -5.2 and -5.6 eV, with the narrower optical band gap and lower HOMO level corresponding to selenated heteroacenes. In thin solid films of the heteroacenes, hole mobility measured using the conventional CELIV technique ranges between 10-5 and 10-4 cm2·V-1·s-1. All these make the proposed condensed-ring compounds a promising platform for the development of hole-transporting materials applicable in organic electronics. Copyright © 2020 American Chemical Society.The research (synthesis of new heteroacenes and investigation of their semiconductor properties) was financially supported by the Russian Science Foundation (project no. 18-13-00409). N.S.D. and N.A.R. would like to acknowledge the financial support for the analytical studies of synthesized compounds from the Ministry of Education and Science of the Russian Federation within the framework of the State Assignment for Research (project no. AAAA-A19-119012490006-1). The authors are grateful to Grigory A. Kim for carrying out the DFT calculations which were performed using ⟨⟨Uran⟩⟩ supercomputer of the Institute of Mathematic and Mechanics of the Ural Branch of the Russian Academy of Sciences. The XRD measurements were performed using the equipment of CKP FMI IPCE RAS

Pyrimidine-Based Push–Pull Systems with a New Anchoring Amide Group for Dye-Sensitized Solar Cells

New donor–π–acceptor pyrimidine-based dyes comprising an amide moiety as an anchoring group have been designed. The dyes were synthesized by sequential procedures based on the microwave-assisted Suzuki cross-coupling and bromination reactions. The influence of the dye structure and length of π-linker on the photophysical and electrochemical properties and on the photovoltaic effectiveness of dye-sensitized solar cells was investigated. An increase in efficiency with a decrease in the length of π-linker was revealed. The D1 dye with only one 2,5-thienylene-linker provided the highest power conversion efficiency among the fabricated dye sensitized solar cells. © 2021 by the authors.IGIC RAS, (AAAA-A20-120101490004-4)Russian Foundation for Basic Research, РФФИ, (18-29-23045)Ministry of Education and Science of the Russian Federation, Minobrnauka, (AAAA-A19-119011790132-7)This work (optical and electrochemical properties) was supported by the Russian Foundation for Basic Research (Project No. 18-29-23045 mk). E.V.V. is grateful to the financial support for the synthetic part from the Ministry of Education and Science of the Russian Federation within the framework of the State Assignment for Research (Project No. AAAA-A19-119011790132-7). NMR experiments were carried out by using equipment of the Center for Joint Use «Spectroscopy and Analysis of Organic Compounds» at the Postovsky Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences. S.A.K and E.V.K. are grateful to the financial support for the fabrication of DSSCs part from IGIC RAS state assignment (Project No AAAA-A20-120101490004-4). V.V.E. is grateful to the partial financial support from the Ministry of Science and Higher Education of the Russian Federation in the frame of the State Task for 2021 IPCE RAS

Polyheteroarylene films with intrinsic switching mechanism for nonvolatile memory applications

This paper presents a polymer material for the nonvolatile memory applications. Current-voltage characteristics show the reproducible nonvolatile switching effect. The effect is observed not only when using two metallic electrodes but also when using two semiconducting electrodes, which reveals the intrinsic nature of the switching phenomenon. (C) 2008 American Institute of Physics.status: publishe

Fast photorefractive polymer composites based on nanocrystalline J-aggregates of the

The hole and electron drift mobility, photoelectric properties as well as influence of temperature, dark current and also relative position of oxidation potentials of the interacting components on photorefractive characteristics of the composites from aromatic polyimide doped with nanocrystalline J-aggregates of a cyanine dye are presented. The nanocrystalline J-aggregates were used as the photosensitizers and also as nonlinear optical chromophores. The experimental electric field dependence of the charge carrier photogeneration efficiency is well fitted by Onsager equation when the quantum yield of the bound thermalized electron-hole pairs φ0=1 and the initial separation of the charges in the pair r0=14.1\uc5. The charge photogeneration time constant determines the response time of the photorefractive grating formation. The polymer composites exhibit gain coefficient Γ=218cm-1 and response time shorter than 20ms at applied electric field 50V/μm and a intensity of each writing beam 30mW/cm2. The net gain coefficient Γ-α=143cm -1