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4-(9'-Hexylcarbazol-3'-yl)benzaldehyde (Cz-Ph-CHO: 4 ) and 4-(9'-hexylcarbazol-3'- yl)benzylidenemalononitrile (Cz-Ph-CN: 5 ) were synthesised with the structure of D-pi-A,where carbazole, phenylene and formyl/dicyanovinyl groups act as electron donor (D), pi-spacer (pi) and electron acceptor (A) units, respectively. The thermal, electrochemical, optical and intramolecular charge transfer (ICT) properties of compounds 4 and 5 were investigated. Compounds 4 and 5 , in particular their ICT behaviour, were also compared with the closely related structure, 2-(9'-hexylcarbazol-3'-yl)-5-pyridinecarbaldehyde (Cz-Py-CHO: 7 ). For the purpose of tuning chemical structure to obtain targeted properties, electrochemical data and absorption and emission measurements suggest that the dicyanovinyl unit in compound 5 is a better acceptor than formyl in compound 4, and that pyridine in compound 7 is a better pi-spacer than benzene in compound 4 , in exerting ICT characteristics such as fluorosolvatochromism and Stokes shifts. (C) 2021 Elsevier B.V. All rights reserved. Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); University of Glasgow; EPSRC ECR Capital Award SchemeUK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/S017984/1] Dr. Ahmet Battal thanks the Scientific and Technological Research Council of Turkey (TUBITAK) for 2219-International Postdoctoral Research Fellowship Programme for Turkish Citizens. Dr William Peveler acknowledges the University of Glasgow for an LKAS Scholarship and the EPSRC ECR Capital Award Scheme (EP/S017984/1) for the Duetta instrument.

Truxene (10,15-dihydro-5H-diindeno[ 1,2-a; 1', 2'-c] fluorene) derived blue emitting materials were designed and developed utilizing Suzuki and Buchwald-Hartwig type cross-coupling reactions. The target molecules T-1, T-2 and T-3 bearing N-carbazolyl, 1-pyrenyl and N-phenyl-N-(pyren-1-yl) substituents, respectively at 2,7,12-positions, were synthesized under mild conditions by palladium-catalyzed reactions in good yields. To improve the solution processability of the material, n-hexyl chains were used as substituents at 5,5'-, 10,10'-, 15,15'-positions. From UV-vis measurements, the absorption maxima were found to be at 330 nm for T-1, 356 nm for T-2 and 412 nm for T-3. The materials were found to be blue emitting with their emission maxima at 385 nm, 425 nm and 490 nm for T-1, T-2 and T-3, respectively. The excited state lifetimes were investigated using time correlated single photon counting and were found to be 10 ns, 1.4 ns and 5.4 ns for T-1, T-2 and T-3, respectively. The highest photoluminescence quantum yield was observed in the case of T-2 corresponding to a value of 0.97. The compounds T-2 and T-3 were used as active materials for the fabrication of solution processed, single layer blue light emitting diodes, with low turn-on voltage (2-3.3 V) and Commission Internationale de l'eclairage (CIE) coordinates corresponding to (0.16, 0.23) and (0.17, 0.36) for T-2 and T-3, respectively.

High efficiency blue fluorescent organic light-emitting diodes (OLEDs), based on 1,3-bis(carbazol-9-yl)benzene (mCP) doped with 4,4&rsquo, bis(9-ethyl-3-carbazovinylene)-1,1&rsquo, biphenyl (BCzVBi), were fabricated using four different hole transport layers (HTLs) and two different electron transport layers (ETLs). Fixing the electron transport material TPBi, four hole transport materials, including 1,1-Bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), N,N&rsquo, Di(1-naphthyl)-N,N&rsquo, diphenyl-(1,1&rsquo, biphenyl)-4&rsquo, diamine(NPB), 4,4&rsquo, Bis(N-carbazolyl)-1,1,-biphenyl (CBP) and molybdenum trioxide (MoO3), were selected to be HTLs, and the blue OLED with TAPC HTL exhibited a maximum luminance of 2955 cd/m2 and current efficiency (CE) of 5.75 cd/A at 50 mA/cm2, which are 68% and 62% higher, respectively, than those of the minimum values found in the device with MoO3 HTL. Fixing the hole transport material TAPC, the replacement of TPBi ETL with Bphen ETL can further improve the performance of the device, in which the maximum luminance can reach 3640 cd/m2 at 50 mA/cm2, which is 23% higher than that of the TPBi device. Furthermore, the lifetime of the device is also optimized by the change of ETL. These results indicate that the carrier mobility of transport materials and energy level alignment of different functional layers play important roles in the performance of the blue OLEDs. The findings suggest that selecting well-matched electron and hole transport materials is essential and beneficial for the device engineering of high-efficiency blue OLEDs.

We have demonstrated three contrasting synthetic strategies to assemble pyrrole-based C-3-symmetric molecule. Here, ring-closing metathesis (RCM), Buchwald-Hartwig cross-coupling and Clauson-Kaas pyrrole synthesis have been used as key steps. Interestingly, readily available starting materials such as 4-aminoacetophenone, 4-bromo acetophenone and 4-nitro acetophenone have been used as starting materials. Grubbs' first generation catalyst (G-I) is useful for one-pot RCM and aromatization sequence without the involvement of additional reagents. We also report photophysical properties of these star shaped molecules. (C) 2018 Elsevier Ltd. All rights reserved.

High photovoltage in perovskite solar cells (PSCs) can be achieved by designing new hole transporting materials (HTMs) with relatively deeper energy levels of the highest occupied molecular orbital (HOMO). Here, we report on the synthesis of a new heteroacene-based HTM (HTM-1) and demonstrate its potential in the fabrication of FAPbBr(3) [FA = CH(NH2)(2)] PSCs yielding V-OC as high as 1.55 V, a record value for this light harvester. The energetic position of the frontier orbitals of HTM-1 was estimated using electrochemical measurements, and the charge transport across the interfaces was studied using steady-state and time-resolved photoluminescence. When spiro-OMeTAD (HOMO = -5.1 eV) is replaced with HTM-1 (HOMO = -5.3 eV), the V-OC increases from 1.51 to 1.55 V, whereas the J(SC) value decreases from 7.0 to 5.7 mA cm(-2). The similar trade-off between J(SC) and V-OC is observed for efficient iodide-based PSCs, suggesting that there is a critical energy level for the HOMO below which overall photovoltaic performance will suffer. After probing at a maximum power point under full-sun illumination at 60 degrees C for a duration of 120 h, the FAPbBr(3) PSCs based on HTM-1 retained approximate to 95 % of their initial efficiency, which demonstrates their robust operational stability.