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Perdeuterated conjugated polymers for ultralowa??frequency magnetic resonance of OLEDs
摘要： The formation of excitons in OLEDs is spin dependent and can be controlled by electron-paramagnetic resonance, affecting device resistance and electroluminescence yield. We explore electrically detected magnetic resonance in the regime of very low magnetic fields (< 1 mT). A pronounced feature emerges at zero field in addition to the conventional spin-1=2 Zeeman resonance for which the Larmor frequency matches that of the incident radiation. By comparing a conventional p-conjugated polymer as the active material to a perdeuterated analogue, we demonstrate the interplay between the zero-field feature and local hyperfine fields. The zero-field peak results from a quasistatic magnetic-field effect of the RF radiation for periods comparable to the carrier-pair lifetime. Zeeman resonances are resolved down to 3.2 MHz, approximately twice the Larmor frequency of an electron in Earth(cid:3)s field. However, since reducing hyperfine fields sharpens the Zeeman peak at the cost of an increased zero-field peak, we suggest that this result may constitute a fundamental low-field limit of magnetic resonance in carrier-pair-based systems. OLEDs offer an alternative solid-state platform to investigate the radical-pair mechanism of magnetic-field effects in photochemical reactions, allowing models of biological magnetoreception to be tested by measuring spin decoherence directly in the time domain by pulsed experiments.
关键词： conjugated polymers,deuteration,magnetic resonance,isotopes,organic light-emitting diodes
更新于2025-09-23 15:19:57
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Prolonged Lifetime in Nanocrystal Light-Emitting Diodes Incorporating MoS <sub/>2</sub> -Based Conjugated Polyelectrolyte Interfacial Layer as an Alternative to PEDOT:PSS
摘要： Colloidal semiconductor nanocrystals (NCs), and recently nanoplatelets (NPLs), owing to their efficient and narrowband luminescence, are considered as frontier materials for the light-emitting diode (LED) technology. NC-LEDs typically incorporate interfacial layers as charge regulators to ensure charge balancing and high performance. In this communication, we show the prolongation of the lifetime of multilayer solution-processed NC-LEDs by combining a self-doped conductive conjugated polyelectrolyte and exfoliated molybdenum disulfide (MoS2) flakes as an alternative to PEDOT:PSS. The ink features a neutral pH and a tunable hydrophobicity that mainly results in a remarkable stability of LEDs, using CdSe/CdZnS NPLs.
关键词： di-chalcogenides,colloidal nanoplatelets,interfacial layers,light-emitting devices,conjugated polyelectrolytes
更新于2025-09-23 15:19:57
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Water-Processed Organic Solar Cells with Open-Circuit Voltages Exceeding 1.3V
摘要： Conjugated polyelectrolytes are commonly employed as interlayers to modify organic solar cell (OSC) electrode work functions but their use as an electron donor in water-processed OSC active layers has barely been investigated. Here, we demonstrate that poly[3-(6’-N,N,N-trimethyl ammonium)-hexylthiophene] bromide (P3HTN) can be employed as an electron donor combined with a water-soluble fullerene (PEG-C60) into eco-friendly active layers deposited from aqueous solutions. Spin-coating a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) layer prior to the P3HTN:PEG-C60 active layer deposition considerably increases the open-circuit voltage (Voc) of the OSCs to values above 1.3 V. Along with this enhanced Voc, the OSCs fabricated with the PEDOT:PSS interlayers exhibit 10-fold and 5-fold increases in short-circuit current density (Jsc) with respect to those employing bare indium tin oxide (ITO) and molybdenum trioxide coated ITO anodes, respectively. These findings suggest that the enhanced Jsc and Voc in the water-processed OSCs using the PEDOT:PSS interlayer cannot be solely ascribed to a better hole collection but rather to ion exchanges taking place between PEDOT:PSS and P3HTN. We investigate the optoelectronic properties of the newly formed polyelectrolytes using absorption and photoelectron spectroscopy combined with hole transport measurements to elucidate the enhanced photovoltaic parameters obtained in the OSCs prepared with PEDOT:PSS and P3HTN.
关键词： frontier orbitals,organic semiconductors,organic solar cells,conjugated polyelectrolytes,sustainable fabrication
更新于2025-09-23 15:19:57
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A New Benzodithiophene Based Donor-Acceptor ??-Conjugated Polymer for Organic Solar Cells
摘要： A new benzodithiophene based donor-acceptor π-conjugated polymer (P1) is designed and explored as the photoactive donor for organic solar cells (OSCs). The synthesized donor polymer, P1 displays a wide absorption profile ranging from 300-750 nm with optical band gap of 1.61 eV and moderate ionization potential of -5.30 eV. It has good solubility in non-halogenated and halogenated organic solvents. Next, we fabricated OSCs with P1 by blending with PC71BM, the pristine polymer processed from chlorobenzene showed PCE of 2.79%. Upon addition of external additive diphenyl ether to the blend showed a dramatic improvement in PCE with maximum of 5.33%. DPE tailored the active layer morphology and showed two times higher PCE than pristine films. These results clearly indicate that the new polymer has a great potentiality for enhancing efficiency upon solvent additives, which will provide new routes for the development of new class of polymers for high-performance air-stable OSCs.
关键词： benzodithiophene based π-conjugated polymer,organic solar cell,morphology,octyl side chain
更新于2025-09-23 15:19:57
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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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Bis(thiena??2a??yl)a??2,1, <scp>3a??benzothiadiazolea??diketopyrrolopyrrole</scp> a??based <scp>acceptora??acceptor</scp> conjugated polymers: Design, synthesis, and the synergistic effect of the substituent on their solar cell properties
摘要： Three acceptor–acceptor conjugated copolymers (TBT-DPP, FTBT-DPP, and HFTBT-DPP) with different substituent groups have been synthesized with palladium-catalyzed Stille coupling condensation polymerization assisted with microwave. Polymer solar cells (PSCs) based on these copolymers as the electron donors and PC71BM as the acceptor have been fabricated. The synergistic effect of the substituent between two fluorine atoms and hexyl alkyl chains in bis(thien-2-yl)-2,1,3-benzothiadiazole fragment on their solar cell properties has been investigated. Both the fluorine atoms and the synergistic effect can improve the solubility of the polymers effectively while the excellent thermal stability properties are still retained. Two fluorine atoms (polymer FTBT-DPP) increased the power conversion efficiency of the PSCs twice compared with TBT-DPP (without substituent). The synergistic effect (polymer HFTBT-DPP) decreased that seriously to zero. Density function theory calculations showed that the conjugation level of the polymer backbone is one of key factors. It demonstrates that the synergistic effect of fluorine atoms and alkyl chains in the same fragment does not always work well in improving the PSCs performance.
关键词： polymer solar cells,diketopyrrolopyrrole polymers,acceptor–acceptor conjugated,bis(thien-2-yl)-2,1,3-benzothiadiazole,synergistic effect
更新于2025-09-23 15:19:57
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Organic-inorganic hybrid heterostructures towards long-wavelength photodetectors based on InGaZnO-Polymer
摘要： Organic-inorganic hybrid heterostructures have attracted considerable attentions due to their wide application in electronics and optoelectronics. In this study, a high-performance red light photodetector based on organic-inorganic heterostructure was successfully fabricated after a systematical optimization in material and device constitution. The conjugated polymer (P(PDI-BDT-O)) with narrow band gap used as light absorber was combined with a layer of indium gallium zinc oxide (IGZO) to construct a bi-layered phototransistor achieving a high mobility as well as high photoresponsivity. Benefiting from both the high absorption coefficient of the polymer over a wide range of wavelength and the perfect matching of band level between polymer and IGZO, the device exhibits an ultrahigh photoresponsivity (212 A/W) and specfic detectivity (2 ? 1012 Jones) for red light at the wavelength of 633 nm. These results demonstrate the great potential of organic-inorganic heterostructures in the application of long-wavelength photodetectors.
关键词： Conjugated polymer,Oxide semiconductor,Organic-inorganic heterostructures,Red light photodetector
更新于2025-09-23 15:19:57
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Synthesis and Evaluation of Scalable D-A-D ??-Extended Oligomers as p-Type Organic Materials for Bulk-Heterojunction Solar Cells
摘要： The synthesis and characterization of four novel donor-acceptor-donor π-extended oligomers, incorporating naphtha(1–b)thiophene-4-carboxylate or benzo(b)thieno(3,2-g) benzothiophene-4-carboxylate 2-octyldodecyl esters as end-capping moieties, and two different conjugated core fragments, is reported. The end-capping moieties are obtained via a cascade sequence of sustainable organic reactions, and then coupled to benzo(c)(1,2,5)thiadiazole and its difluoro derivative as the electron-poor π-conjugated cores. The optoelectronic properties of the oligomers are reported. The novel compounds revealed good film forming properties, and when tested in bulk-heterojunction organic photovoltaic cell devices in combination with PC61BM, revealed good fill factors, but low efficiencies, due to their poor absorption profiles.
关键词： organic electronics,Cascade organic reactions,fused aromatic rings,organic photovoltaics,π-conjugated oligomers,bulk-heterojunction organic solar cells,direct arylation
更新于2025-09-23 15:19:57
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MoS <sub/>2</sub> Assisted Self-Assembled Poly (3-hexylthiophene) Thin Films at Air/Liquid Interface for High-Performance Field-Effect Transistors under Ambient Condition
摘要： It is a key challenge to achieve long-range ordering in nanoscale morphology of π-conjugated polymers for efficient charge transport in organic electronic devices. The long-range ordering and aggregation in poly (3-hexylthiophene) (P3HT) has been accomplished by introducing two dimensional (2D) Molybdenum disulfide (MoS2) nanosheets in polymer matrix followed by ultrasonication in chloroform. Thin films of synthesized P3HT/MoS2 nanocomposites having various fractions of MoS2 in the P3HT matrix have been fabricated on the air/liquid interface. The UV visible absorption spectroscopy has been employed to investigate the nature of aggregation and exciton bandwidth in the resultant films deposited at the air/liquid interface. Moreover, grazing incidence X-ray diffraction (GIXD) analysis, and atomic force microscopy (AFM), reveal the long-range ordering and highly crystalline thin films with the edge-on orientation of polymer chains over the substrate. Further, the impact of aggregation, morphology, and orientation on macroscopic charge transport performance is elaborately estimated by fabricating organic field-effect transistors (OFETs). The hole mobility as high as 0.160 ± 0.007 cm2V-1s-1, has been achieved for P3HT/MoS2 (1%) nanocomposite under ambient condition.
关键词： organic field-effect transistors,MoS2,π-conjugated polymers,nanocomposites,P3HT,charge transport
更新于2025-09-23 15:19:57
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MEH-PPV photophysics: insights from the influence of a nearby 2D quencher
摘要： The effect of 2D quenching on single chain photophysics was investigated by spin coating 13 nm thick films of polystyrene lightly doped with MEH-PPV onto CVD grown graphene and observing the changes in several photoluminescent (PL) observables. With 99% of the PL quenched, we found a 60% drop in the PL lifetime, along with a significant blue-shift of the PL emission due to the preferential quenching of emission at longer wavelengths. During photo-bleaching, the blue spectral shift observed for isolated polymers was eliminated in the presence of the quencher up until 70% of the polymer was photo-bleached. Results were interpreted using a static disorder induced conjugation length distribution model. The quencher, by opening up a new non-radiative decay channel, ensures that excitons do not have sufficient time to migrate to nearby lower energy chromophores. The reduction of energy transfer into the lowest-energy chromophores thus reduces their rate of photo-bleaching. Finally, the difference between the quenched and non-quenched spectra allows the rate of energy transfer along the polymer backbone to be estimated at ～2 ns?1.
关键词： fluorescence lifetime,photo-bleaching,photophysics,conjugated polymers,fluorescence quenching,single molecules,graphene
更新于2025-09-23 15:19:57