Investigation of biphenyl enamines for applications as p-type semiconductors

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New solution-processable carbazole derivatives as deep blue emitters for organic light-emitting diodes

Two new compounds based on three carbazole units connected by triple bonds as π-spacers have been developed as deep blue emitters for organic light-emitting diodes (OLEDs). Their optical and electrochemical properties were examined and their charge carrier transport properties were investigated by means of the xerographic time-of-flight (XTOF) technique. The prepared diodes demonstrate the feasibility of the new molecules as effective emitters in the deep blue region yielding devices with low turn-on voltages

4.9% Efficient Sb2S3 Solar Cells from Semitransparent Absorbers with Fluorene-Based Thiophene-Terminated Hole Conductors

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Over 18% ternary polymer solar cells enabled by a terpolymer as the third component

“Ternary blending” and “random terpolymerization” strategies have both proven effective for enhancing the performance of organic solar cells (OSCs). However, reports on the combination of the two strategies remain rare. Here, a terpolymer PM6-Si30 was constructed by inserting chlorine and alkylsilyl-substituted benzodithiophene (BDT) unit (0.3 equivalent) into the state-of-the-art polymer PM6. The terpolymer exhibitsadeep highest-occupied-molecular-orbital energy and good miscibility with both PM6 and BTP-eC9 (C9) and enables its use as a third component into PM6:PM6-Si30:C9 bulk-heterojunction for OSCs. The resulting cells exhibit maximum power conversion efficiency (PCE) of 18.27%, which is higher than that obtained for the optimized control binary PM6:C9-based OSC (17.38%). The enhanced performance of the PM6:PM6-Si30:C9 cells is attributed to improved charge transport, favorable molecular arrangement, reduced energy loss and suppressed bimolecular recombination. The work demonstrates the potential of random terpolymer as a third component in OSCs and highlights a new strategy for the construction of a ternary system with improved photovoltaic performance

Chloride-Based Additive Engineering for Efficient and Stable Wide-Bandgap Perovskite Solar Cells

Metal halide perovskite based tandem solar cells are promising to achieve power conversion efficiency beyond the theoretical limit of their single-junction counterparts. However, overcoming the significant open-circuit voltage deficit present in wide-bandgap perovskite solar cells remains a major hurdle for realizing efficient and stable perovskite tandem cells. Here, a holistic approach to overcoming challenges in 1.8 eV perovskite solar cells is reported by engineering the perovskite crystallization pathway by means of chloride additives. In conjunction with employing a self-assembled monolayer as the hole-transport layer, an open-circuit voltage of 1.25 V and a power conversion efficiency of 17.0% are achieved. The key role of methylammonium chloride addition is elucidated in facilitating the growth of a chloride-rich intermediate phase that directs crystallization of the desired cubic perovskite phase and induces more effective halide homogenization. The as-formed 1.8 eV perovskite demonstrates suppressed halide segregation and improved optoelectronic properties

Monolithic perovskite/silicon tandem solar cell with >29% efficiency by enhanced hole extraction

Tandem solar cells that pair silicon with a metal halide perovskite are a promising option for surpassing the single-cell efficiency limit. We report a monolithic perovskite/silicon tandem with a certified power conversion efficiency of 29.15%. The perovskite absorber, with a bandgap of 1.68 electron volts, remained phase-stable under illumination through a combination of fast hole extraction and minimized nonradiative recombination at the hole-selective interface. These features were made possible by a self-assembled, methyl-substituted carbazole monolayer as the hole-selective layer in the perovskite cell. The accelerated hole extraction was linked to a low ideality factor of 1.26 and single-junction fill factors of up to 84%, while enabling a tandem open-circuit voltage of as high as 1.92 volts. In air, without encapsulation, a tandem retained 95% of its initial efficiency after 300 hours of operation.BMBF, 03SF0540, Nachwuchsgruppe MeSa-Zuma: Entwicklung von spektral optimierten, hocheffizienten und langzeitstabilen Perowskit/Silizium Tandem SolarzellenBMWi, 0324288C, Verbundvorhaben: ProTandem - Demonstration der Produktionstauglichkeit von Perowskit-Silizium Tandemsolarzellen; Teilvorhaben: Entwicklung von Kontaktschichten für die Silizium-Heterojunction BottomzelleEC/H2020/763977/EU/Perovskite Thin-film Photovoltaics (PERTPV)/PERTPVDFG, 423749265, Identifizierung und Unterdrückung von Grenzflächenrekombination für hocheffiziente Perowskit-SolarzellenDFG, 402726906, SPP 2196: Perowskit-Halbleiter: Von fundamentalen Eigenschaften zur Anwendun

An Efficient Scalable Synthesis of 2,3-Epoxypropyl Phenylhydrazones

A series of mono and di-N-2,3-epoxypropyl N-phenylhydrazones have beenprepared on a large scale by reaction of the corresponding N-phenylhydrazones of9-ethyl-3-carbazolecarbaldehyde, 9-ethyl-3,6-carbazoledicarbaldehyde, 4-dimethyl-amino-, 4-diethylamino-, 4-benzylethylamino-, 4-(diphenylamino)-, 4-(4,4-4\u27-dimethyl-diphenylamino)-, 4-(4-formyldiphenylamino)- and 4-(4-formyl-4\u27-methyldiphenyl-amino)benzaldehyde with epichlorohydrin in the presence of KOH and anhydrousNa2SO4

TADF versus TTA emission mechanisms in acridan and carbazole-substituted dibenzo[a,c]phenazines: Towards triplet harvesting emitters and hosts

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