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Improved Transistor Performance by Modulating Molecular Packing with Donor and Acceptor Moieties
摘要： The joint of the donor and acceptor moieties allows a facile and effective strategy to develop novel organic conjugated materials. However, few works report the understanding of the donor-acceptor interactions at the molecular level. Herein, we develop three small molecules contain one acceptor motif with different amounts of the donor unit. By the combination of theoretical calculation and energy level characterization, the lowest occupied molecular orbital (LUMO) levels of the three molecules were proven to be almost identical. The molecular packing modes were evaluated from crystal structure prediction. Due to the donor-acceptor interactions, the packing mode can be tuned from the 1D slipped stacking to the 2D brick layer. The 2D molecular packing and charge transport channel endowed the materials a higher electron mobility of 3.29 cm2 V?1 s?1 in the single-crystal field-effect transistors after such modulation.
关键词： organic field-effect transistor,conjugated molecules,donor-acceptor,crystal structure prediction
更新于2025-09-23 15:22:29
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Bond theory, Terahertz spectra and dielectric studies in donor-acceptor (Nb-Al) substituted ZnTiNb <sub/>2</sub> O <sub/>8</sub> system
摘要： As a donor and acceptor separately, Nb5+ and Al3+ are used to substitute Ti4+ in the ixiolite ZnTiNb2O8 system for the first time. The dielectric responses in the terahertz range of this system are initially studied based on the data from terahertz time-domain transmitted spectroscopy. Combined with ligand field theory, the formation of a secondary phase of ZnAl2O4 is reasonably explicated. Then, the origins of the lower dielectric loss and the terahertz wave absorption coefficient are determined to be the high chemical bond covalency and effective phase control. For the composition of ZnTi0.85(Al0.5Nb0.5)0.15Nb2O8 sintered at 1180 °C, a low dielectric loss (< 5×10-3 @ 0.5 THz) and absorption coefficient (< 10 cm-1 @ 0.5 THz) are obtained, which make this kind of material propitious for developing terahertz dielectric devices.
关键词： complex chemical bond theory,covalency,microwave and terahertz,dielectric properties,donor-acceptor substituted
更新于2025-09-23 15:22:29
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Novel A2-D-A1-D-A2 type NIR absorbing symmetrical squaraines based on 2, 3, 3, 8-tetramethyl-3H-pyrrolo [3, 2-h] quinoline: Synthesis, photophysical, electrochemical, thermal properties and photostability study
摘要： Two novel acceptor–donor-acceptor-donor-acceptor type pi-conjugated symmetrical squaraine dyes, denoted by PQSQ 1 and PQSQ 2 based on 2, 3, 3, 8-tetramethyl -3H-pyrrolo [3,2-h] quinoline were successfully synthesized for the first time to arrive absorption and emission at NIR region. These dyes comprise indolenines as electron donor units, squaryl ring as a central electron acceptor and pyridines as terminal electron acceptor units. The relationship between molecular structures and photophysical properties of these dyes was studied in comparison with their parent compounds (ISQ and N-Et ISQ). These novel squaraine dyes displayed an intense absorption within the range 671 to 692 nm in polar to non- polar solvents respectively with good molar extinction coefficients (? 105 Lmol-1cm-1). Compared to their parent squaraines, both dyes showed red-shifted absorption (33 - 44 nm) as well as emission (38 - 59 nm) due to the electron-accepting ability of the ancillary pyridine acceptors and extended pi-conjugation. These dyes exhibited negative solvatochromism and Reichardt's ET (30) scale was applied to propose a quantitative relationship of the relative stability of ground and excited-state of these squaraines with solvent polarity. The electrochemical and computational properties of these symmetrical squaraines were investigated with the help of cyclic voltammetry and density functional theory (DFT). Moreover, PQSQ 1-2 exhibited high thermal and photo-stability. These A2-D-A1-D-A2 type dyes showed improved photostabilities compared to their parent D-A-D type dyes.
关键词： 2, 3, 3, 8-tetramethyl -3H-pyrrolo [3, 2-h] quinoline,NIR absorbing dyes,acceptor-donor-acceptor-donor-acceptor,squaraines,DFT computations,red shift
更新于2025-09-23 15:21:21
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Acceptora??donora??acceptor type molecules for high performance organic photovoltaics a?? chemistry and mechanism
摘要： The study of organic photovoltaics (OPVs) has made great progress in the past decade, mainly attributed to the invention of new active layer materials. Among various types of active layer materials, molecules with A–D–A (acceptor–donor–acceptor) architecture have demonstrated much great success in recent years. Thus, in this review, we will focus on A–D–A molecules used in OPVs from the viewpoint of chemists. Notably, the chemical structure–property relationships of A–D–A molecules will be highlighted and the underlying reasons for their outstanding performance will be discussed. The device stability correlated to A–D–A molecules will also be commented on. Finally, an outlook and challenges for future OPV molecule design and device fabrication to achieve higher performance will be presented.
关键词： chemical structure–property relationships,device stability,organic photovoltaics,acceptor–donor–acceptor,molecule design
更新于2025-09-23 15:21:01
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Cardanol and Guaiacol sourced Solution-Processable Green Small Molecules based Organic Solar Cells
摘要： An environment compatible organic solar cell (OSC) has potential to build a global clean energy infrastructure for the world. However, much less attention has been focused on the structures sourced from greener origin, to enhance the sustainability aspect of these devices. Herein, we report a rational design, synthesis and characterization of donor (D)-acceptor (A) based green organic small molecules, consisting of difluoro-2,1,3-benzothiadiazole (BTF2) as the acceptor, with a thiophene (T) and renewable resource materials, cardanol (C) and guaiacol (G) as the donor materials. The reference molecule, abbreviated as T4BTF2, is fully petro-sourced, while C2T2BTF2, G2T2BTF2 are partly renewable origin molecules. A broad and strong absorption characteristics ranging from 300 to 600 nm along with higher thermal stability is supportive for the utility of the greener origin small molecules in solar cells. Density Functional Theory (DFT) calculations revealed that G2T2BTF2 is highly planar than C2T2BTF2 due to the difference in the positioning of alkyl/alkoxy chain. Bulk heterojunction OSCs with PC71BM as the acceptor, G2T2BTF2 exhibited the high Voc of 0.83 V among all the analysed small molecules. When compared with the reference molecule T4BTF2, G2T2BTF2 showed a high PCE of 5.56 % with a high Jsc of 10.98 mA/cm2 and FF of 0.61, whereas the PCEs of T4BTF2 and C2T2BTF2 are 3.98 % and 3.23%, respectively. Our work demonstrates a rational approach to synthesize and develop green organic semiconductors using the bio-feedstock derived starting materials for realizing efficient and environment compatible OSCs.
关键词： Organic small-molecules,Green organic solar cells,Renewable phenols,fluorine substituents,Sustainable,donor-acceptor
更新于2025-09-23 15:21:01
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Highly Polarized Coumarin Derivatives Revisited: Solvent-controlled Competition Between Proton Coupled Electron Transfer and Twisted Intramolecular Electron Transfer
摘要： Linking a polarized coumarin unit with an aromatic substituent via an amide bridge results in weak electronic coupling affecting the intramolecular electron transfer (ET) process. As a result of this, interesting solvent-dependent photophysical properties can be observed. In polar solvents, electron transfer in coumarin derivatives of this type induces a mutual twist of electron-donating and electron-accepting molecular units (TICT process) that opens radiationless decay processes (internal conversion). In the dyad with the strongest intramolecular hydrogen bond, the planar form is stabilized so twisting can only occur in highly polar solvents, whereas fast proton coupled electron transfer (PCET process) occurs in non-polar n-alkanes. The kPCET rate constant decreases linearly with the fluorescence maximum energy in different solvents. This observation is explained in terms of competition between electron and proton transfer from a highly polarized (~15 D) and fluorescent locally-excited (1LE) state to a much less polarized (~4 D) charge-transfer (1CT) state, a unique occurrence. Photophysical measurements performed for a family of related coumarin dyads together with results of quantum-chemical computations give insight into the mechanism of the ET process which is followed by either a TICT or PCET process. Our results reveal that dielectric solvation of the excited state slows down the PCET process, even in non-polar solvents.
关键词： coumarins,donor-acceptor systems,absorption,fluorescence,chromophores
更新于2025-09-23 15:21:01
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Study of point defects in wide-bandgap Cu <sub/>2</sub> CdGeS <sub/>4</sub> microcrystals by temperature and laser power dependent photoluminescence spectroscopy
摘要： We present temperature and laser power dependent photoluminescence (PL) study of high quality wide-bandgap Cu2CdGeS4 microcrystals. At T = 10 K three PL bands were detected at about 1.919 eV (#1), 1.855 eV (#2) and 1.748 eV (#3). The temperature and laser power dependencies indicate that the properties of PL bands can be explained by donor- acceptor pair model, where the #1 and #2 bands result from a recombination between distant pairs involving ≈ 30 meV and different deep donor defects. The #3 PL the same shallow acceptor VCu with EA band originates from the deep donor-deep acceptor pair recombination where the depth of deep acceptor defect is more than 157 meV. Detailed analysis of the PL spectra show the absence of deep potential or band gap fluctuations in this material making it suitable for photovoltaic applications.
关键词： Cu2CdGeS4,photoluminescence,defects,wide bandgap,donor-acceptor pairs
更新于2025-09-23 15:21:01
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Tackling Performance Challenges in Organic Photovoltaics: An Overview about Compatibilizers
摘要： Organic Photovoltaics (OPVs) based on Bulk Heterojunction (BHJ) blends are a mature technology. Having started their intensive development two decades ago, their low cost, processability and flexibility rapidly funneled the interest of the scientific community, searching for new solutions to expand solar photovoltaics market and promote sustainable development. However, their robust implementation is hampered by some issues, concerning the choice of the donor/acceptor materials, the device thermal/photo-stability, and, last but not least, their morphology. Indeed, the morphological profile of BHJs has a strong impact over charge generation, collection, and recombination processes; control over nano/microstructural morphology would be desirable, aiming at finely tuning the device performance and overcoming those previously mentioned critical issues. The employ of compatibilizers has emerged as a promising, economically sustainable, and widely applicable approach for the donor/acceptor interface (D/A-I) optimization. Thus, improvements in the global performance of the devices can be achieved without making use of more complex architectures. Even though several materials have been deeply documented and reported as effective compatibilizing agents, scientific reports are quite fragmentary. Here we would like to offer a panoramic overview of the literature on compatibilizers, focusing on the progression documented in the last decade.
关键词： mixing interfaces,additives,bulk heterojunction,morphology modulators,donor/acceptor interface,organic photovoltaics,compatibilizers
更新于2025-09-23 15:21:01
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Synthesis and Photovoltaic Properties of Boron ?2a??Ketoiminate Dyes Forming A Linear Donora????a??Acceptor Structure
摘要： Organoboron complexes are of interest as chromophores for dye sensitizers owing to their light-harvesting and carrier-transporting properties. In this study, compounds containing boron β-ketoiminate (BKI) as a chromophore were synthesized and used as dye sensitizers in dye-sensitized solar cells. The new dyes were orange or red crystals and showed maximum absorptions in the 410–450 nm wavelength region on titanium dioxide substrates. These electrodes exhibited maximum efficiencies of over 80% in incident photon-to-current conversion efficiency spectra, suggesting that the continuous process of light absorption–excitation–electron injection was effectively performed. Open-circuit photovoltages were relatively high owing to the large dipole moments of the BKI dyes with a linear molecular structure. Thus, a maximum power conversion efficiency of 5.3% was successfully observed. Comparison of BKI dyes with boron β-diketonate dyes revealed certain differences in solution stability, spectral properties, and photovoltaic characteristics.
关键词： chelates,boron,donor-acceptor systems,dyes/pigments,energy conversion
更新于2025-09-23 15:21:01
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Rational design of pyrrolopyrrole-aza-BODIPY-based acceptora??donora??acceptor triads for organic photovoltaics application
摘要： Acceptor-donor-acceptor triads consisting of diketopyrrolopyrrole (DPP) or pyrrolopyrrole aza-BODIPY (PPAB) or both as acceptors and cyclopentadithiophene as a donor were rationally designed for near infrared (NIR) photovoltaics application. Among them, the PPAB-based triad exhibited the highest power conversion efficiency of 3.88% owing to the panchromatic absorption in the UV/vis/NIR regions.
关键词： pyrrolopyrrole-aza-BODIPY,organic photovoltaics,acceptor-donor-acceptor triads,near infrared photovoltaics
更新于2025-09-23 15:19:57