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Extensive Study of Rhodanine-Arylamine-Based Chromophores: Consolidated Optical, DFT/TD-DFT and Non-Linear Optical Properties
摘要： Three push-pull rhodanine-arylamine based D-π-A dyes (2a-2c) are prepared to study the effect of donor on electronic, linear and nonlinear optical properties. The dyes, 2a,2b and 2c have a vinyl spacer conjugated with triphenylamine, julolidine, and carbazole donors respectively, with a methoxy group and rhodanine-3-acetic acid. The dyes exhibited solvent dependent absorption-emission up to the red region with large Stokes shifts (2a = 77-130 nm). This dyes possess charge transfer characteristics as established by transition dipole moment (μeg), dipole moment ratio (μe/μg), Generalised Mulliken-Hush analysis, and electron distribution (DFT). The non-linear optical study revealed that quadratic hyperpolarizability (μβCT) are 1098.9 (2a), 515.0 (2b) and 339.6 x 10-48 e.s.u. (2c) depending on donor strength. The intrinsic hyperpolarizabilities fall below βint0 = 10-3/2 limit i.e. less than unity. Solvatochromic two-level model is used to study the trends in two photon cross-section (σ2PA). The dye 2a exhibited high σ2PA, 216 GM (λmax 485 nm and 564 nm). The dyes 2a and 2c with analogue dye 3a show reverse saturable absorption (RSA) therefore, show positive third order nonlinear absorption coefficient, β and reasonable values of third order nonlinear susceptibility and high laser damage threshold. The Re χ(3) factors are responsible for the high values of χ(3) in the range of 0.77 to 8.09 x 10-12 e.s.u. Therefore, this material would serve as good candidate in the photonic application.
关键词： hyperpolarizability,Z scan,Arylamine donors,σ2PA,LDT
更新于2025-09-23 15:23:52
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Kinetic effects and oxidation pathways of sacrificial electron donors on the example of the photocatalytic reduction of molecular oxygen to hydrogen peroxide over illuminated titanium dioxide
摘要： Sacrificial electron donors are frequently used in photocatalytic reactions to enhance the performance of the reaction, typically short-chain alcohols as well as their respective aldehydes and acids are used. This study focuses on the differences between the individual electron donors regarding their oxidation rates, mechanistic pathways, the influence of the intermediates and their direct impact on the H2O2 generation. The individual H2O2 formation rates of 16 different electron donors, photonic and faradaic efficiencies for H2O2 production are carefully discussed. Furthermore, a new multi-reaction pathway for t-butanol oxidation is postulated and critically examined.
关键词： Alcohol oxidation,Reaction kinetics,Reaction pathway,Hydrogen peroxide,Photocatalysis,Sacrificial electron donors
更新于2025-09-23 15:22:29
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Buchwald-Hartwig Coupling at the Naphthalenediimide Core: Access to Dendritic, Panchromatic NIR Absorbers with Exceptionally Low Band Gap
摘要： The ?rst successful Buchwald?Hartwig reaction at the naphthalenediimide core is reported, leading to the coupling of diverse secondary aromatic amines including dendritic donors. The G1-dendrimer-based donor exhibit blackish color, providing access to black absorbing systems. λ onset values up to 1070 nm was achieved, which is the maximum from a single NDI sca?old. These dyes also manifest multielectron reservoir properties. A total of eight-redox states with a band gap of ～0.95 eV was accomplished.
关键词： dendritic donors,low band gap,black absorbing systems,Buchwald?Hartwig reaction,naphthalenediimide,multielectron reservoir properties,NIR absorbers
更新于2025-09-23 15:21:21
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Progress of the key materials for organic solar cells
摘要： Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight, flexibility and roll-to-roll fabrication. Nowadays, 18% power conversion efficiency has been achieved in the state-of-the-art organic solar cells. The recent rapid progress in organic solar cells relies on the continuously emerging new materials and device fabrication technologies, and the deep understanding on film morphology, molecular packing and device physics. Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance. The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors. In this review, we focus on those star materials and milestone work, and introduce the molecular structure evolution of key materials. These key materials include homopolymer donors, D-A copolymer donors, A-D-A small molecular donors, fullerene acceptors and nonfullerene acceptors. At last, we outlook the challenges and very important directions in key materials development.
关键词： D-A copolymer donors,nonfullerene acceptors,key materials,organic solar cells,fullerene acceptors
更新于2025-09-23 15:21:01
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Efficient and Stable Deep-Blue Fluorescent Organic Light-Emitting Diodes Employing a Sensitizer with Fast Triplet Upconversion
摘要： Multiple donor–acceptor-type carbazole–benzonitrile derivatives that exhibit thermally activated delayed fluorescence (TADF) are the state of the art in efficiency and stability in sky-blue organic light-emitting diodes. However, such a motif still suffers from low reverse intersystem crossing rates (kRISC) with emission peaks <470 nm. Here, a weak acceptor of cyanophenyl is adopted to replace the stronger cyano one to construct blue emitters with multiple donors and acceptors. Both linear donor–π–donor and acceptor–π–acceptor structures are observed to facilitate delocalized excited states for enhanced mixing between charge-transfer and locally excited states. Consequently, a high kRISC of 2.36 × 106 s?1 with an emission peak of 456 nm and a maximum external quantum efficiency of 22.8% is achieved. When utilizing this material to sensitize a blue multiple-resonance TADF emitter, the corresponding device simultaneously realizes a maximum external quantum efficiency of 32.5%, CIEy ≈ 0.12, a full width at half maximum of 29 nm, and a T80 (time to 80% of the initial luminance) of > 60 h at an initial luminance of 1000 cd m?2.
关键词： stable deep-blue devices,sensitized emission,high reverse intersystem crossing,thermally activated delayed fluorescence,multiple donors and acceptors
更新于2025-09-23 15:21:01
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Developing Wide Bandgap Polymers with Single Benzodithiophene-Based Unit for Efficient Polymer Solar Cells
摘要： In this work, a series of solely benzodithiophene-based wide bandgap polymer donors, namely PBDTT, PBDTS, PBDTF and PBDTCl, were developed for efficient polymer solar cells (PSCs) by just varying the heteroatoms into the conjugated side chains. The effects of sulfuration, fluorination and chlorination were also investigated systematically on the overall properties of these BDT-based polymers. The HOMO levels could be lowered gradually by introducing sulfur, fluorine and chlorine atoms into the side chains, which contributed to the stepwise increased Voc (from 0.78 V to 0.84 V) in the related PSCs using Y6 as the electron acceptor. On the other hand, above side chain engineering strategy could promote the polymer chain interactions and fine-tune the phase separation of active blends, leading to the enhanced absorption, ordered molecular packing and crystallinity. Among them, the chlorinated PBDTCl exhibited not only high level absorption and crystallinity, but also the most balanced hole/electron charge transport and the most optimized morphology, giving rise to the best PCE of 13.46% with a Voc of 0.84 V, a Jsc of 23.16 mA cm-2 and an FF of 69.2 %. The chlorination strategy afforded PBDTCl synthetic simplicity but high efficiency, showing its promising photovoltaic applications for realizing low-cost practical PSCs in near future.
关键词： synthetic simplicity,benzodithiophene,sole donor unit,wide bandgap polymer donors,polymer solar cells
更新于2025-09-23 15:21:01
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Narrowing the Band Gap: The Key to High-Performance Organic Photovoltaics
摘要： Organic photovoltaics (OPVs) have attracted considerable attention in the last two decades to overcome the terawatt energy challenge and serious environmental problems. During their early development, only wide-band-gap organic semiconductors were synthesized and employed as the active layer, mainly utilizing photons in the UV?visible region and yielding power conversion e?ciencies (PCEs) lower than 5%. Afterward, considerable e?orts were made to narrow the polymer donor band gap in order to utilize the infrared photons, which led to the enhancement of the PCE from 5% to 12% in about a decade. Since 2017, the study of narrow-band-gap non-fullerene acceptors helped usher in a new era in OPV research and boosted the achievable the PCE to 17% in only 3 years. In essence, the history of OPV development in the last 15 years can be summarized as an attempt to narrow the band gap of organic semiconductors and better position the energy levels. There are multiple bene?ts of a narrower band gap: (1) considerable infrared photons can be utilized, and as a result, the short-circuit current density can increase signi?cantly; (2) the energy o?set of the lowest unoccupied molecular orbital energy levels or highest occupied molecular orbital energy levels between the donor and acceptor can be reduced, which will reduce the open-circuit voltage loss by minimizing the loss caused by the donor/acceptor charge transfer state; (3) because of the unique molecular orbitals of organic semiconductors, the red-shifted absorption will induce high transmittance in the visible region, which is ideal for the rear subcells in tandem-junction OPVs and transparent OPVs.
关键词： Organic photovoltaics,narrow-band-gap,non-fullerene acceptors,power conversion efficiencies,polymer donors
更新于2025-09-23 15:21:01
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Exciplexa??Based Organic Lighta??Emitting Diodes with Neara??Infrared Emission
摘要： Near-infrared exciplex can weaken molecular design difficulties, and has the advantage of easy bathochromic-shift spectra via selecting the suitable electron donors and acceptors. In this contribution, exciplex is applied to fabricate near-infrared (NIR) organic light-emitting diodes (OLEDs) incorporating a synthesized fluorescent material 3-([1,1″:3′,1″-terphenyl]-5′-yl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile (APDC-tPh) and a commercially available material 4,4′,4″-tris(carbazol-9-yl)triphenylamine (TCTA). The device having a mixed TCTA:APDC-tPh as an emitting layer shows a 730 nm NIR emission with a maximum external quantum efficiency (EQE) of about 0.1%, while the device having 2-[4-(diphenylamino)phenyl]-10,10-dioxide-9H-thioxanthen-9-one (TXO-TPA):APDC-tPh as the emitting layer exhibits an emission peak of 704 nm with a maximum EQE of 1.27%. These results prove the feasibility of fabricating the efficient exciplex-based NIR OLEDs.
关键词： donors and acceptors,near-infrared OLEDs,exciplexes,bathochromic shifts
更新于2025-09-19 17:13:59
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Vacuum‐Deposited Bi-ternary Organic Photovoltaics
摘要： Ternary blend organic photovoltaics (OPVs) have been introduced to improve solar spectral absorption and reduce energy losses beyond that of binary blend OPVs, but the difficulties in simultaneously optimizing the morphology of three molecular components results in devices that have generally exhibited performance inferior to analogous binary OPVs. Here we introduce a small molecule-based bi-ternary OPV comprising two individual, vacuum deposited binary bulk heterojunctions fused at a planar junction without component intermixing. In contrast to previous reports where the open circuit voltage (VOC) of a conventional, blended ternary cell lies between that of the individual binaries, the VOC of the bi-ternary OPV corresponds to one of the constituent binaries, depending on the order in which they are stacked relative to the anode. Additionally, dipole-induced energy-level realignment between the two binary segments necessary to achieve maximum efficiency is observed only when using donor-acceptor-acceptor’ dipolar donors in the photoactive heterojunctions. The optimized bi-ternary OPV shows improved performance compared to its two constituent binary OPVs, achieving a power conversion efficiency of 10.6 – 0.3% under AM 1.5G 1 sun (100 mW/cm2) simulated illumination with VOC = 0.94 – 0.01 V, a short circuit current density of 16.0 – 0.5 mA cm?2 and a fill factor of 0.70 – 0.01.
关键词： organic photovoltaics,bi-ternary,ternary blend,vacuum deposition,dipolar donors
更新于2025-09-19 17:13:59
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Novel swivel-cruciform 5,5′-bibenzothiadiazole based small molecule donors for efficient organic solar cells
摘要： 5,5′-bibenzothiadiazole (BBT), which is a dimer of widely used electron deficient building block benzothiadiazole (BT), offers great promise for developing highly efficient electron donors because of its unique structural features. However, a small quantity of work has been reported on BBT based donors, and their overall performances are still far behind those of their BT counterparts. In order to make a contribution in this regard, the novel small molecules were synthesized and applied as donor materials in the bulk heterojunction solar cells, in which the BBT was used as the central node. Compared with the corresponding linear BT based molecule, the swivel-cruciform BBT based molecule exhibited significantly enhanced photovoltaic performance with an impressive power conversion efficiency of 7.21%, which is the best reported device performance based on BBT-core materials in organic solar cells. These results indicate the great potential of BBT for high performance solar cells.
关键词： Swivel-cruciform structure,Organic solar cells,5,5′-bibenzothiadiazole unit,Small molecule donors
更新于2025-09-19 17:13:59