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Determining the sequence and backbone structure of a??semi-statisticala?? copolymers as donora??acceptor polymers in organic solar cells
摘要： Organic photovoltaics (OPVs) are attracting significant attention due to the growing demand for economically viable and renewable energy sources. With efficiencies exceeding 16.5%, single junction bulk heterojunction (BHJ) devices are amongst the most promising and are nearing commercialisation. One recent avenue of research has focused on statistical conjugated copolymers. However, a detailed investigation as to why these materials can achieve higher power conversion efficiencies than their regular alternating counterparts is seldom reported. This work describes an investigation into donor–acceptor polymers demonstrating how differing monomer activities can lead to differing microstructures in a simple batch reaction, which in turn demonstrates promising optoelectronic and morphological properties required for organic photovoltaic devices. A one pot condensation polymerisation reaction with three monomers leads to an ABA triblock structure from differing monomer reactivities. This structure in turn leads to visualised phase separation which is possibly linked to an increase in performance. Further to this we report on the reliability of the Stille coupling for the synthesis of conjugated polymers.
关键词： Organic photovoltaics,Donor–acceptor polymers,Bulk heterojunction devices,Statistical conjugated copolymers,Stille coupling
更新于2025-09-23 15:19:57
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Impact of intramolecular H bond and n-π* interactions on photophysical and CO2 sensing properties of laterally appended D-π-A triarylboron compounds
摘要： Several examples of laterally appended donor-π-acceptor (D-π-A) boron compounds based on a biphenyl unit have been synthesized and fully characterized. Intramolecular H bonds or n-π* interactions have been found to have a great impact on the photophysical/fluorescent properties of these compounds. Some members of these compounds have been found to display fluorescent response toward CO2.
关键词： Triarylboron,Carbon dioxide sensing,Donor-acceptor compound
更新于2025-09-23 15:19:57
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Photophysical Impact of Diacetylenic Conjugation on Classical Donor-Acceptor Electronic Energy Pair
摘要： Organic fluorophores with extended π-conjugation are important for their wide-spread applications. The present work provides photophysical insights of a diacetylene bridged classical donor-acceptor electronic energy pair, naphthalene-pyrene, in comparison with its part molecular structures, naphthyl and pyrenyl acetylenes as well as parent naphthalene and pyrene chromophores. The diacetylenic dye loses individual spectral identities of the donor and acceptor fluorophores exhibiting a locally excited (LE) emission (~411 nm) from the overall molecular entity with high fluorescence quantum yields (0.55–0.84) in non-aqueous media. In contrast to parent pyrene, the hybrid derivative shows strongly allowed S0→S1 transition. In mixed-aqueous media, the dye forms J-aggregates displaying a new red-shifted absorption (~425 nm) as well as emission (~510 nm) band. Unlike the hybrid dye, the naphthyl and pyrenyl acetylenes do not form aggregates. In the aggregate state of the hybrid fluorophore, electronic energy transfer takes place from the naphthyl moiety to pyrenyl ring. The excited state photophysical properties of the dye is exploited to vapor sensing in solid state.
关键词： vapor sensing,Organic fluorophores,donor-acceptor electronic energy pair,diacetylene bridged,naphthalene-pyrene,locally excited emission,J-aggregates,electronic energy transfer,π-conjugation,fluorescence quantum yields
更新于2025-09-23 15:19:57
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Synergy of light harvesting and energy transfer as well as short-range charge shift reactions in multicomponent conjugates
摘要： We report herein on the design, the synthesis, and the characterization of a panchromatic, charge stabilizing electron donor–acceptor conjugate: (BBPA)3–ZnPor–ZnPc–SubPc 1. Each component, that is, bis(biphenyl)phenylamine (BBPA), Zn(II) porphyrin (ZnPor), Zn(II) phthalocyanine ZnPc, and subphthalocyanine (SubPc), has been carefully chosen and modified to enable a cascade of energy and charge transfer processes. On one hand, ZnPor, has been functionalized with three electron-donating BBPA as primary and secondary electron donors and to stabilize the final charge-separated state, and, on the other hand, a perfluorinated SubPc has been selected as ultimate electron acceptor. In addition, the ZnPc unit contains several trifluoromethylphenyl moieties to match its energy levels to those of the other components. In fact, irradiation of the heteroarray 1 triggers a cascade of light harvesting across the entire visible range, unidirectional energy transfer, exergonic charge separating, and short-range charge shifting to afford a (BBPA)3(cid:129)+–ZnPor–ZnPc–SubPc(cid:129)? charge-separated state. The lifetime of the latter reaches well into the range of tens of nanoseconds with a 14% quantum yield.
关键词： charge stabilizing,light harvesting,panchromatic,charge transfer,energy transfer,porphyrinoids,electron donor–acceptor conjugate
更新于2025-09-19 17:15:36
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Time-resolved photoluminescence spectral analysis of phonon-assisted DAP and e-A recombination in N+B-doped <i>n</i> -type 4H-SiC epilayers
摘要： It is crucial to clarify the roles of phonon-assisted donor-acceptor pairs (DAPs) and free-to-acceptor (e-A) emissions in n-type 4H-SiC doped with nitrogen (N) and boron (B), where N and B induce the shallow donor and the D center (deep B) acceptor levels, respectively, in order to understand the complicated carrier recombination mechanism, as well as developing fluorescent SiC with a high color rendering index by controlling the ratio of the two overlapped emissions. Here, time-resolved photoluminescence (TRPL) spectral analyses were performed, in which phonon-assisted DAPs and e-A components were individually recognized. The D center-related green luminescence (1.6–2.8 eV) shows a non-exponential decay followed by a very slow decay in TRPL measurements at room temperature (RT). It emerges that most of the DAP emission intensities decay much faster than e-A emissions and contribute to what is initially fast and non-exponential decay at low temperatures, while the slow decay at RT is mainly from e-A emissions. At a much higher temperature, such as 473 K, only the e-A emission remains and the decay transforms from non-exponential to exponential behavior. High-temperature thermal quenching of e-A emissions exhibits different behaviors for samples with differing B doping concentrations. An activation energy of 0.6 eV was estimated from the Arrhenius plot of e-A emission intensity from a B-doped sample, which matches the D center level. This indicates that the hole thermal emission rate is greatly enhanced at a high temperature, which accelerates the decay of e-A emission intensity at high temperatures.
关键词： donor-acceptor pair,time-resolved photoluminescence,silicon carbide,D center,boron doping
更新于2025-09-19 17:15:36
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“Four-Component” Assembly of Polyaromatic 4H-Cyclopenta[b]thiophene Structures based on GaCl3-Promoted Reaction of Styrylmalonates with 5-Phenylthiophene-2-carbaldehyde
摘要： New "four-component" self-assembly of polyaromatic thiophene structures based on styrylmalonates and 5-phenylthiophene-2-carbaldehyde has been developed. This process is promoted by GaCl3 and involves two [2+3]-annulation steps on the CHO-groups and para-substitution into one Ph-ring. The main feature of discovered process is a high diastereoselectivity with a significant increase in molecular complexity. The resulting polyaromatic structures containing two thiophene moieties in each structure have intense color and strong absorption in a near UV spectral region with absorption maxima in the range of 257–360 nm.
关键词： Donor-acceptor cyclopropanes,4H-cyclopenta[b]thiophenes,5-Phenylthiophene-2-carbaldehyde,Styrylmalonates,Gallium trichloride,Multi-component processes
更新于2025-09-19 17:15:36
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The effect of imprint on remanent piezoelectric properties and ferroelectric aging of PbZr <sub/>0.52</sub> Ti <sub/>0.48</sub> O <sub/>3</sub> thin films
摘要： Ferroelectric films suffer from both aging and degradation under high ac-field drive conditions due to loss of polarization with time. In this study, the roles of defect chemistry and internal electric fields on the long-term stability of the properties of piezoelectric films were explored. For this purpose, lead zirconate titanate (PZT) films with a Zr/Ti ratio of 52/48 doped with Mn- (PMZT) or Nb- (PNZT) were deposited on Pt coated Si substrates by the sol-gel method. It was demonstrated that the magnitude of the internal field is much higher in PMZT films compared to PNZT films after poling in the temperature range of 25-200°C under an electric field of -240 kV/cm. The development of the internal field is thermally activated, with activation energies from 0.5±0.06 to 0.8±0.1 eV in Mn doped films and from 0.8±0.1 to 1.2±0.2 eV in Nb doped films. The different activation energies for imprint suggests that the physical mechanism underlying the evolution of the internal field in PMZT and PNZT films differs; the enhanced internal field upon poling is attributed to (1) alignment of oxygen vacancy – acceptor ion defect dipoles (((Mn''_Ti - V_O^{??})_x, (Mn'_Ti - V_O^{??})') in PMZT films, and (2) thermionic injection of electron charges and charge trapping in PNZT films. In either case, the internal field reduces back switching, enhances the remanent piezoelectric properties, and dramatically improves the aging behavior. PMZT films exhibited the greatest enhancement, with reduced high temperature (180°C) aging rates of 2-3%/decade due to improved stability of the poled state. In contrast, PNZT films showed significantly larger high temperature aging rates (15.5%/decade) in the piezoelectric coefficient, demonstrating that the fully poled state was not retained with time.
关键词： aging,PZT,sol-gel,thin film,donor,acceptor,imprint
更新于2025-09-19 17:15:36
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Doping of Donor-Acceptor Polymers with Long Side Chains via Solution Mixing for Advancing Thermoelectric Properties
摘要： One-step doping of conjugated polymers by solution mixing is typically performed instead of sequential doping because of its simplicity. However, doped polymer solutions often exhibit poor solubility, and the presence of dopants in the produced films can disturb the molecular ordering of polymer structures. In this work, effective pairs of two donor-acceptor (D-A) type polymers and a molecular dopant characterized by high solution stability and good thermoelectric properties of the prepared thin films have been reported. The presence of long side chains in the polymer structures preserves their original solubilities and crystallinity in the solution and thin-film states, respectively, even at large amounts of added dopant (up to 38 mol%). Furthermore, the relatively shallow levels of the highest occupied molecular orbitals of the selected D-A polymers enable efficient charge transfer from the dopant species. Owing to their good charge transport properties, the doped D-A polymers exhibit outstanding thermoelectric properties with a maximum power factor of 31.5 μW m?1 K?2, which is more than an order of magnitude higher than those of the control samples prepared from donor-only poly(3-hexylthiophene).
关键词： molecular doping,donor-acceptor polymers,power factors,long side chains,solution mixing,organic thermoelectric materials
更新于2025-09-19 17:15:36
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Self-assembled bulk heterojunctions from integral molecules with nonconjugately linked donor and acceptor units for photovoltaic applications
摘要： The bi-continuous interpenetrating network of donor/acceptor with suitable phase-separated domain size is crucial for highly efficient organic bulk heterojunction solar cells considering that it guarantees effective exciton dissociation and smooth charge transport. For traditional binary blend bulk heterojunction, the photoactive layer is a simple physical mixture of donor and acceptor, the size of phase separation is primarily determined by the aggregation characteristics of the donor and acceptor respectively, it is hard to control and stabilize. To solve this problem, a kind of donor-acceptor integral molecule with donor units and acceptor units linked by non-conjugated flexible linking units has been proposed. The energy levels and the absorption spectra of the integral molecules can be easily tailed by tuning the donor and the acceptor units. Furthermore, the integral molecules can form a microphase separated bulk heterojunction of donor phase and acceptor phase through a self-assembly process of the molecule, which is governed by the flexible linking unit, responsible for connecting the donor and acceptor units. Since the donor and acceptor units of the integral molecules are connected by the non-conjugated units, the scale of aggregation and the morphology stability could be easily controlled. In this review, we first introduce the unique characteristics of the three typical donor-acceptor integral molecules and then highlight their current developments. For each donor-acceptor molecule, we attempt to give a detailed summarization on their design and synthesis, and an in-depth understanding on the basic mechanism of molecular self-assembly and the performance comparison of SMSCs. In the end, the prospect and potential improvements of donor-acceptor integral molecule are addressed, and we believe that emerging donor-acceptor molecule provide great opportunities for efficient and stable organic solar cells.
关键词： double-cable polymer,self-assembly,donor-acceptor integral molecule,donor-acceptor small molecule,single material organic solar cell,block copolymer
更新于2025-09-19 17:13:59
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Dopant-free X-shaped D-A type hole-transporting materials for p-i-n perovskite solar cells
摘要： Azomethine compounds are accessible for palladium-free routes, paving a way for developing highly efficient and eco-friendly hole-transporting materials. This study reports three organic dopant-free X-shaped molecules (named D31, D32, and D33) were systematically designed, synthesized and characterized for fabricating p-i-n perovskite solar cells. The X-shaped design is based on a benzene core unit with four arms attached. Two of them are triphenylamines and two are azomethine bridges connected to functionalized phenyl rings (-H, -OCH3, -CN). These materials show suitable energy levels with respect to that of CH3NH3PbI3 perovskite. Based on this design, it is found that the hydrophobic nature of the three new compounds not only favors the formation of large grained and dense perovskite films but also improves stability of the devices. More encouragingly, the cyano-substituted D33 with donor-acceptor (D-A) type structure exhibit the superiority of high hole mobility and good film-forming property. The optimized unencapsulated device based on D33 in ambient environment exhibit 17.85% efficiency and retained 70% of the initial PCE after 400 hours.
关键词： perovskite solar cells,azomethine,dopant-free,hole-transport materials,donor-acceptor
更新于2025-09-19 17:13:59