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  • 1.
    Baryshnikov, Gleb V.
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bohdan Khmelnytsky National University, Ukraine.
    Gawrys, Pawel
    Ivaniuk, Khrystyna
    Witulski, Bernhard
    Whitby, Richard J.
    Al-Muhammad, Ayham
    Minaev, Boris
    Cherpak, Vladyslav
    Stakhira, Pavlo
    Volyniuk, Dmytro
    Wiosna-Salyga, Gabriela
    Luszczynska, Beata
    Lazauskas, Algirdas
    Tamulevicius, Sigitas
    Grazulevicius, Juozas V.
    Nine-ring angular fused biscarbazoloanthracene displaying a solid state based excimer emission suitable for OLED application2016In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 24, p. 5795-5805Article in journal (Refereed)
    Abstract [en]

    A new biscarbazoloanthracene consisting of nine fused aromatic rings, including two pyrrole units, has been obtained in a straightforward and convergent synthesis. Computational chemistry and conformational analysis revealed that the semiconductor's molecule is not planar, the two carbazole moieties being helical twisted from the plane of the anthracene unit. Photophysical and electrochemical measurements showed that this angular fused heteroacene has a low lying HOMO energy level with a wide band gap despite its extended pi-conjugated molecular framework. Based on its relatively low-lying HOMO level, the semiconductor promises a high environmental stability in comparison to other related linear fused acenes and heteroacenes. The biscarbazoloanthracene has been applied as the light emitting layer in a white light emitting diode (WOLED). It is proposed that the white OLED feature is due to dual light emission properties from the active semiconductor layer being based on both the molecular luminescence of the small molecule and a discrete excimer emission made possible by suitable aggregates in the solid state. Noteworthy, this is the first reported example of such a behavior observed in a small molecule heteroacene rather than an oligomer or a polymer.

  • 2. Chen, S.
    et al.
    Li, W.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhu, W. -H
    Aggregation-controlled photochromism based on a dithienylethene derivative with aggregation-induced emission2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 10, p. 2717-2722Article in journal (Refereed)
    Abstract [en]

    We report novel aggregation-induced emission (AIE) characteristics involving aggregation-controlled photochromism properties of a dithienylethene derivative, BTE-EQ, where two quinolinemalononitrile (EQ) units are covalently attached to a dithienylethene core. The typical AIE effect of BTE-EQ has been found to originate from the AIE character of the EQ units with respect to the reference compound BTE, which does not contain an EQ unit. The photochromism study, together with density functional theory calculations, reveals that the photochromic activity of BTE-EQ can be reversibly switched off and on by controlling the aggregation state during the AIE process, which provides a novel route to controlling the photochromism of diarylethenes.

  • 3. Giri, Anupam
    et al.
    Goswami, N.
    Pal, M.
    Zar Myint, M. T.
    Al-Harthi, S.
    Singha, A.
    Ghosh, B.
    Dutta, Joydeep
    Deparment in Nanotechnology, Water Research Center, Sultan Qaboos University, Al-Khoudh, Oman.
    Pal, S. K.
    Rational surface modification of Mn3O4 nanoparticles to induce multiple photoluminescence and room temperature ferromagnetism2013In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 1, no 9, p. 1885-1895Article in journal (Refereed)
    Abstract [en]

    Surface modification can have a significant influence on the materials behavior at the nanoscale and can lead to nanostructures with novel properties. Here, we demonstrate the surface modification induced multiple photoluminescence and room temperature ferromagnetic activation of Mn3O4 nanoparticles (NPs). Employing a systematic variation of the ligands, their functional groups and the structural position of the functional groups, we have identified the necessary and sufficient structural requirements of the surface co-ordinating ligands, in order to induce unprecedented optical/magnetic responses from the NPs. Using a multitude of spectroscopic techniques, we have investigated the mechanism behind the emergence of the multiple photoluminescence (PL), and it is revealed that the presence of a α-hydroxy carboxylate moiety in the ligands is necessary to activate the Jahn-Teller (J-T) splitting of Mn3+ ions on the NP surface and the corresponding d-d transitions along with the ligand-to-metal charge transfer transitions (LMCT, associated with Mn2+/3+-ligand interactions) is the key factor. However, the presence of a carboxylate group on the surface coordinating ligands is sufficient to activate the room temperature ferromagnetism of the NPs. Moreover, it has been observed that the ligands that induced the smallest crystal field splitting energy (CFSE) resulted in the strongest ferromagnetic activation of the NPs. Finally, the functionalized material has been identified as an efficient catalyst for the photo-degradation of a model cationic organic dye. Apart from the fundamental scientific interest, these results represent a promising route for the rational design of Mn 3O4 NPs adaptable to diverse applications.

  • 4. Grybauskaite-Kaminskiene, Gintare
    et al.
    Ivaniuk, Khrystyna
    Bagdziunas, Gintautas
    Turyk, Pavlo
    Stakhira, Pavlo
    Baryshnikov, Gleb V.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bohdan Khmelnytsky National University, Ukraine.
    Volyniuk, Dmytro
    Cherpak, Vladyslav
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bohdan Khmelnytsky National University, Ukraine.
    Hotra, Zenon
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Siberian Federal University, Russian Federation.
    Grazulevicius, Juozas Vidas
    Contribution of TADF and exciplex emission for efficient "warm-white" OLEDs2018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 6, p. 1543-1550Article in journal (Refereed)
    Abstract [en]

    The bicarbazole derivative 4,4'-(9H, 9'H-[3,3'-bicarbazole]-9,9'-diyl) bis(3-(trifluoromethyl) benzonitrile), denoted as pCNBCzoCF(3), was synthesized and tested for white OLED applications. pCNBCzoCF3 demonstrated an extremely small value of the singlet-triplet energy gap that caused intensive thermally activated delayed fluorescence (TADF). In addition, this compound is able to form exciplex-type excited states at the interface with star-shaped 4,40,400-tris[phenyl(m-tolyl) amino] triphenylamine (m-MTDATA). Combining the TADF emission of pCNBCzoCF3 with the exciplex emission from the pCNBCzoCF(3) m-MTDATA interface, we fabricated a number of highly efficient "warm-white'' OLEDs, the electroluminescence of which was close to candle emission. The best device demonstrated a very high brightness of 40 900 Cd m(-2) (at 15 V), current efficiency of 53.8 Cd A(-1) and power efficiency of 19.3 lm W-1, while the external quantum efficiency reached 18.8%. The fabricated devices demonstrated high emission characteristics even for the standard test at 1000 Cd m(-2) (current efficiency of 46.2 Cd A(-1), power efficiency of 10.6 lm W-1, EQE of 17.0%).

  • 5. Huang, Wei
    et al.
    Wang, Huan
    Sun, Lu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Li, Bo
    Su, Jianhua
    Tian, He
    Propeller-like D-pi-A architectures: bright solid emitters with AIEE activity and large two-photon absorption2014In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 2, no 33, p. 6843-6849Article in journal (Refereed)
    Abstract [en]

    Two novel molecules TABzPA and TATpPA with D-pi-A structure and large pi-conjugation have been synthesized via Wittig reaction. Unlike common molecules, which exhibit the aggregation-caused quenching (ACQ) phenomenon, TABzPA and TATpPA exhibit aggregation-induced emission enhancement (AIEE) activity: weak luminescence in common solvents but strong emission when aggregated as nanoparticles and solid powders. Due to their intramolecular charge transfer (ICT) attribution and AIEE features, TABzPA and TATpPA display bathochromic effects. Combining ICT and AIEE features, these molecules are intensely yellow solid emitters with high quantum efficiencies of about 23.2% and 24.1%. Moreover, TABzPA and TATpPA have excellent two-photon absorption (2PA) properties owing to good planarity and large pi-conjugation. The values of 2PA cross sections at 800 nm are 7590 GM and 7648 GM. The excellent optical properties of TABzPA and TATpPA pave the way for future potential applications in biophotonics and optoelectronics.

  • 6. Ivaniuk, K. B.
    et al.
    Baryshnikov, Glib V.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bohdan Khmelnytsky National University of Cherkasy, Ukraine.
    Stakhira, P. Y.
    Pedersen, S. K.
    Pittelkow, M.
    Lazauskas, A.
    Volyniuk, D.
    Grazulevicius, J. V.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Khmelnytsky National University of Cherkasy, Ukraine.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Siberian Federal University, Russia.
    New WOLEDs based on pi-extended azatrioxa[8]circulenes2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 17, p. 4123-4128Article in journal (Refereed)
    Abstract [en]

    New stable WOLEDs based on pi-extended azatrioxa[8]circulenes have been fabricated. Combining the own blue emission of the azatrioxa[8] circulenes with the yellow-green emission of the "m-MTDATA:azatrioxa[8]circulene'' exciplex a broad visible region, from 400 to 700 nm, is covered. The so constructed WOLEDs exhibit a luminance exceeding 23 700 cd m(-2) and an external quantum efficiency reaching 3%.

  • 7. Li, Wenlong
    et al.
    Cai, Yunsong
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tian, He
    Zhu, Wei-Hong
    Sterically hindered diarylethenes with a benzobis(thiadiazole) bridge: photochemical and kinetic studies2015In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 33, p. 8665-8674Article in journal (Refereed)
    Abstract [en]

    Four rationally designed diarylethenes (DAEs) 1-4 with a benzobis(thiadiazole) bridge are specifically designed for gaining insights into steric effects on photochromic performances. It is shown that, upon increasing steric hindrance, the exchanging rate between two main conformers in the ring-open form gradually slows down, offering the opportunity for isolating photoactive anti-parallel conformers. Impressively, the separated anti-parallel conformer shows high cyclization quantum yields over the unresolved common DAEs. The typical donor-pi-acceptor (D-pi-A) feature in ring-open DAEs 1-4 endows their prominent fluorescence, which can be conveniently modulated by photocyclization. In the ring-closed form, the excess steric hindrance is found to seriously disrupt the thermal bistability, and particularly 3c fades quickly with a half-life of several hours at ambient temperature. In contrast, both 1c and 2c exhibit excellent stability, which originates from the stabilization effects of intramolecular hydrogen bonds. This work demonstrates the steric effects on the photochemical and kinetic behaviors of DAEs, providing a unique approach to develop photochromic DAEs with high photosensitivity.

  • 8. Silvearv, Fredrik
    et al.
    Larsson, Peter
    Jones, Sarah. L. T.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden .
    Larsson, J. Andreas
    Establishing the most favorable metal-carbon bond strength for carbon nanotube catalysts2015In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 14, p. 3422-3427Article in journal (Refereed)
    Abstract [en]

    We have studied a wide range of transition metals to find potential carbon nanotube (CNT) catalysts for chemical vapor deposition (CVD) production. The adhesion strengths between a CNT and a metal cluster were calculated using first principle density functional theory (DFT) for all 1st, 2nd and 3rd row transition metals. We have developed the criterion that the metal-carbon adhesion strength per bond must fulfill a Goldilocks principle for catalyzing CNT growth and used it to identify, besides the well known catalysts Fe, Co and Ni, a number of other potential catalysts, namely Y, Zr, Rh, Pd, La, Ce and Pt. Our results are consistent with previous experiments performed either in a carbon arc discharge environment or by a CVD-process with regard to CNT catalyst activity.

  • 9. Song, X.
    et al.
    Zhang, W.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Jiang, H.
    Shen, C.
    Zhu, W. -H
    Influence of ethynyl position on benzothiadiazole based D-A-π-A dye-sensitized solar cells: Spectral response and photovoltage performance2016In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 39, p. 9203-9211Article in journal (Refereed)
    Abstract [en]

    The ethynyl group has been widely employed in dye-sensitized solar cells (DSSCs) as an efficient π-spacer to prolong conjugation and promote electronic coupling at the interface of TiO2 films. However, systematic studies of the ethynyl position on metal-free organic sensitizers remain relatively rare. Herein we report indoline-based organic dyes bearing an ethynyl group at different positions of D-A-π-A organic dyes. Based on the reference dye D1, we inserted an ethynyl unit in either the left or right side of benzothiadiazole to construct two novel dyes D2 and D3. It was found that inserting an ethynyl unit to the side of the anchoring group obtained a higher molar extinction coefficient with a red shift in the absorption band. Interestingly, D2 and D3 displayed a better photovoltaic performance with respect to D1. In particular, D3 exhibits an over 90 mV enhanced open-circuit voltage (VOC) than D2 owing to a longer electron lifetime and slower charge recombination. With this incredible increase of VOC, D3 bestows a high efficiency of 7.13% with respect to D1 and D2. Coadsorption strategies are exploited for further improving the cell behaviour. As a result, cosensitization with a long-wavelength-responsive dye WS-2 was demonstrated to efficiently compensate the light-harvesting, achieving an excellent efficiency of 9.83% in the iodine electrolyte. This work has paved a useful and practical way for molecular engineering in D-A-π-A metal-free organic dyes.

  • 10. Wang, Shangshang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhao, Wandong
    Chen, Xuanying
    Zhang, Junji
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zou, Qi
    Zhu, Liangliang
    Chen, Wenbo
    Cu2+-Selectivity gated photochromism in Schiff-modified diarylethenes with a star-shaped structure2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 2, p. 282-289Article in journal (Refereed)
    Abstract [en]

    A great deal of effort has been devoted to developing gated photochromic systems due to their advantages in the smart materials and opto-electronic fields, whereas the gating function through certain ions has rarely been addressed. Since the photochromic materials gated by ions can be readily further processed into a multi-functional molecular switch and probe, we herein designed and conveniently synthesized a star-shaped Schiff-based diarylethene derivative showing typical photochromic properties in solution. This compound possesses two response channels (colorimetric and fluorogenic) to Cu2+ ions with photoswitching characteristics, making it a viable photochromic probe. It is noteworthy that its photochromic reactivity can be locked when Cu2+ ions are introduced into the solution. Moreover, the photoinactive and photoactive states can be interchanged reversibly by binding Cu2+ ions and unbinding Cu2+ ions using EDTA, which shows promise for application in multi-controlled molecular switches and smart materials. The mechanism of the photochromic properties locked by Cu2+ ions is reasonably proposed by theoretical simulations. These results could be valuable for the further development of molecular switching systems with multiple stimuli responses.

  • 11.
    Yang, Xiaoyong
    et al.
    Southwest Univ Sci & Technol, Natl Collaborat Innovat Ctr Nucl Waste & Environm, Mianyang 621010, Sichuan, Peoples R China.;Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Mat Them Div, Box 516, S-75120 Uppsala, Sweden..
    Singh, Deobrat
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Mat Them Div, Box 516, S-75120 Uppsala, Sweden..
    Xu, Zhitong
    Southwest Univ Sci & Technol, Natl Collaborat Innovat Ctr Nucl Waste & Environm, Mianyang 621010, Sichuan, Peoples R China..
    Wang, Ziwei
    Southwest Univ Sci & Technol, Natl Collaborat Innovat Ctr Nucl Waste & Environm, Mianyang 621010, Sichuan, Peoples R China..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Mat Them Div, Box 516, S-75120 Uppsala, Sweden..
    An emerging Janus MoSeTe material for potential applications in optoelectronic devices2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 39, p. 12312-12320Article in journal (Refereed)
    Abstract [en]

    Motivated by the extraordinary physical and chemical properties of Janus transition-metal dichalcogenides (TMDs) due to the change of the crystal field originating from their asymmetry structures, the electronic and optical properties of the MoSeTe monolayer in 2H and 1T phases are systematically studied by first-principles calculations, and a detailed comparison with the parental MoSe2 and MoTe2 monolayer is made. It is found that 2H-MoSeTe exhibits a direct bandgap of 1.859 eV and an indirect band gap of 0.391 eV in the 1T phase, resulting in a different way to interact with sunlight. Besides, the obtained results show that the SOC has little effects on the band gaps. The calculated optical properties show a significant red shift from the MoSe2 to MoSeTe to MoTe2 monolayer. However, a blue shift is observed from the in-plane to out-of-plane direction. Moreover, both electron-electron and electron-hole correlation effects are considered for obtaining the optical spectra of systems by G(0)W(0) and G(0)W(0) + BSE approaches. Besides, the absorption coefficient value reaches up to 1 x 10(6) cm(-1) in both phases, implying the high efficiency in the utilization of solar energy for the MoSeTe monolayer. Additionally, the 1T-MoSeTe monolayer is a good hot mirror material in that its maximum reflectivity could reach up to 51% in the infrared region. Additionally, the average optical absorbance of the Janus MoSeTe monolayer in the visible light region is calculated to be about 2% and the corresponding average transmittance is around 80%. More importantly, the difference in the optical response for the two side surfaces is considered in our work due to the intrinsic asymmetric structure of Janus MoSeTe. These results not only predict the great potential application of Janus MoSeTe in optoelectronics-electronic devices, but may enable the discovery of new optical science and the realization of various light emissions, detection, modulation and manipulation functions of specific frequencies.

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