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Effect of Photocrosslinking of D‐A Thiophene Copolymers on the Performance of Single‐Material Solar Cells
摘要： Side-chain C60-fullerene functionalized alkylthiophene copolymers with different regioregularity and fullerene content are successfully synthesized using a simple and straightforward post-polymerization functionalization procedure based on a Grignard coupling reaction. The products are employed as single materials in photoactive layers of organic photovoltaic solar cells. The use of double-cable polymers allows an enhanced control on the nano-morphology of the active blend, reducing the phase-segregation phenomena as well as the macroscale separation between the electron acceptor and donor components. With the insertion of a thin layer of gold nanoparticles between buffer and active layer of the cells, a conversion efficiency of 5.68% is obtained. Moreover, an increased stability over time is achieved when the copolymers are photocrosslinked immediately after the annealing procedure, leading to acceptable efficiencies even after 80 h of accelerated ageing, a key feature for widespread applicability of the prepared devices.
关键词： conjugated polymers,metathesis,functionalization of polymers,fullerenes
更新于2025-09-12 10:27:22
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Wide-Band-Gap Phthalimide-Based D-π-A Polymers for Nonfullerene Organic Solar Cells: The Effect of Conjugated π-Bridge from Thiophene to Thieno[3,2- <i>b</i> ]thiophene
摘要： Conjugated polymers with D-π-A backbone structures have been intensively investigated and have largely promoted the rapid progress of organic solar cells (OSCs). However, as one of the simplest electron-accepting (A) units, phthalimide (PhI), only attracts less attention to construct promising D-π-A photovoltaic polymers in OSC community. Thus the correlations between the chemical structure-optoelectronic properties-photovoltaic performance need to be systematically investigated. Here, we combined the PhI moiety with the electron-donating (D) unit benzodithiophene (BDT) to synthesize two D-π-A copolymers PE80 and PE81, where the π-bridge corresponds to the thiophene (T) and thieno[3,2-b]thiophene (TT) respectively. When blended with a low bandgap (Eg=1.33 eV) non-fullerene acceptor Y6, PE81 achieved a power conversion efficiency (PCE) of 10.21% with an open circuit voltages (VOC) of 0.90 V, which are much higher than those of PE80:Y6 device (PCE = 4.11% and VOC = 0.88 V). Our results indicate that PhI is also a promising electron-deficient unit to construct photovoltaic polymers and using TT π-bridge is simple strategy to improve the photovoltaic performance of D-π-A polymers.
关键词： non-fullerene organic solar cells,D-π-A backbone,Conjugated polymers,thieno[3,2-b]thiophene,phthalimide
更新于2025-09-12 10:27:22
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Toward Scalable PbS Quantum Dot Solar Cells Using a Tailored Polymeric Hole Conductor
摘要： Colloidal quantum dot (CQD) solar cells processed from pre-exchanged lead sulfide (PbS) inks have received great attention in the development of scalable and stable photovoltaic devices. However, the current hole-transporting material (HTM) 1,2-ethanedithiol-treated PbS (PbS-EDT) CQDs have several drawbacks in terms of commercialization, including the need for oxidation and multilayer fabrication. Conjugated polymers are an alternative HTM with adjustable properties. Here we propose a series of conjugated polymers (PBDB-T, PBDB-T(Si), PBDB-T(S), PBDB-T(F)) for PbS CQD solar cells as HTMs. Through polymer side-chain engineering, we optimize the model polymer PBDB-T to tune the energy levels, increase hole mobility, improve solid-state ordering, and increase free carrier density. CQD solar cells based on modified polymer PBDB-T(F) exhibit a best power conversion efficiency (PCE) of 11.2%, which outperforms the devices based on conventional PbS-EDT HTM (10.6%) and is currently the highest PCE for PbS solar cells based on organic HTMs.
关键词： conjugated polymers,PbS,hole-transporting material,Colloidal quantum dot,power conversion efficiency,solar cells
更新于2025-09-12 10:27:22
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Conjugated Polymer-Quantum Dot Hybrid Materials for Pathogen Discrimination and Disinfection
摘要： In this work, a new platform for pathogen discrimination and killing based on a conjugated polymer-quantum dot hybrid material was designed and constructed through the fluorescence resonance energy transfer (FRET) process. The hybrid material comprises water-soluble anionic CdSe/ZnS quantum dots (QDs) and a cationic poly(fluorene-alt-phenylene) derivative (PFP) through electrostatic interactions, thus promoting efficient FRET between PFP and QDs. Upon addition of different pathogen strains, the FRET from PFP to QDs was interrupted because of the competitive binding between PFP and the pathogens. Complexation of PFP and QDs also reduced the dark toxicity to a more desirable level, therefore potentially realizing the controllable killing of pathogens. The technique provides a promising theranostic platform in pathogen discrimination and disinfection based on FRET and phototoxicity of the PFP and QDs.
关键词： FRET,pathogens discrimination and killing,quantum dots,conjugated polymers,theranostic platform
更新于2025-09-12 10:27:22
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Tuning the optoelectronic properties of oligothiophenes for solar cell applications by varying the number of cyano and fluoro substituents for solar cell applications: A theoretical study
摘要： Chemical modifications through substitution are observed to be effective in controlling the optoelectronic properties of various polymers for different applications. In this study, density functional theory–based calculations are employed to investigate the optoelectronic properties of several oligothiophenes based on poly(3-hexylthiophene-2,5-diyl) by varying the number of fluoro and cyano substituents attached. The resulting structures of the polymer derivatives are affected by the electrostatic interactions between the cyano or fluoro groups and the adjacent thiophene unit. Of the two, cyano substitution results in much lower frontier orbital energies for the same number of substituents. It was observed that a decrease in the highest occupied molecule orbital and lowest unoccupied molecular orbital energies correlates very strongly with the number of cyano and fluoro substituents. The effect of the cyano and fluoro groups on the frontier orbitals is also demonstrated and observed to correlate strongly with a lowering of the highest occupied molecule orbital and lowest unoccupied molecular orbital energies as the number of substituents is varied. The predicted solar cell characteristics reveal that most cyano and fluoro derivatives will have improved characteristics compared to unsubstituted poly(3-hexylthiophene-2,5-diyl). This theoretical study shows that by varying the number of electron-withdrawing substituents, the optoelectronic properties may be tuned for solar cell applications.
关键词： density functional theory,optoelectronic properties,organic solar cells,conjugated polymers,computational chemistry
更新于2025-09-12 10:27:22
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Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron–Electron Resonance
摘要： Synthetic polymers are mixtures of chains with different lengths, and their chain length and chain conformation is often experimentally characterized by ensemble averages. We demonstrate that Double-Electron-Electron-Resonance (DEER) spectroscopy can reveal the chain length distribution, and chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki-Miyaura Coupling Polymerization (cSMCP). The required spin-labeled chain ends were introduced efficiently via a TEMPO-substituted initiator and chain terminating agent, respectively, with an in situ catalyst system. Individual precise chain length oligomers as reference materials were obtained by a stepwise approach. Chain length distribution, chain conformation and flexibility can also be accessed within poly(fluorene) nanoparticles.
关键词： controlled polymerization,polymer particles,wormlike chain model,conjugated polymers,Electron paramagnetic resonance,double-Electron-Electron resonance (DEER),distance determination
更新于2025-09-12 10:27:22
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1,5-Naphthyridine-based conjugated polymers as co-sensitizers for dye-sensitized solar cells
摘要： 1,5-naphthyridine-based conjugated polymers (P1 and P2) were synthesized and extensively characterized by 1H NMR, thermogravimetric analysis (TGA), FT-IR. These polymers were employed as co-sensitizers in DSSCs sensitized with Ru (II) based N3 dye. In comparison to the N3 sensitized device, the P1 and P2 co-sensitized solar cells demonstrated enhanced open circuit voltage, (VOC) of 825 and 788 mV and better ?ll factor (FF) of 59 and 58%, respectively. The co-sensitization of P1 and P2 with N3 increased the overall e?ciencies to 5.88% and 6.21%, respectively, as compared to 5.58% for N3 sensitizer alone. The fabricated device based on N3 co-sensitized with P2 displayed higher charge recombination resistances as compared to the devices based on N3 alone or N3 co-sensitized with P1. The conjugated polymers are believed to enhance light harvesting ability and reduce the charged recombination in the co-sensitized solar cells.
关键词： 1,5-Naphthyridine-based conjugated polymers,Solar cell,Co-sensitization,N3 dye
更新于2025-09-11 14:15:04
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Intrinsically distinct hole and electron transport in conjugated polymers controlled by intra and intermolecular interactions
摘要： It is still a matter of controversy whether the relative difference in hole and electron transport in solution-processed organic semiconductors is either due to intrinsic properties linked to chemical and solid-state structure or to extrinsic factors, as device architecture. We here isolate the intrinsic factors affecting either electron or hole transport within the same film microstructure of a model copolymer semiconductor. Relatively, holes predominantly bleach inter-chain interactions with H-type electronic coupling character, while electrons’ relaxation more strongly involves intra-chain interactions with J-type character. Holes and electrons mobility correlates with the presence of a charge transfer state, while their ratio is a function of the relative content of intra- and inter-molecular interactions. Such fundamental observation, revealing the specific role of the ground-state intra- and inter-molecular coupling in selectively assisting charge transport, allows predicting a more favorable hole or electron transport already from screening the polymer film ground state optical properties.
关键词： electron transport,organic semiconductors,conjugated polymers,charge transfer state,hole transport
更新于2025-09-11 14:15:04
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Small Band gap Boron Dipyrromethene-Based Conjugated Polymers for All-Polymer Solar Cells: The Effect of Methyl Units
摘要： Naphthalene diimide (NDI)-based conjugated polymers have been widely used as the nonfullerene electron acceptor for all-polymer solar cells (all-PSCs), but their low absorption coefficient in the near-infrared (NIR) region severely limits the light harvesting ability in solar cells and hence lowers their photovoltaic performance. In this work, two narrow band gap donor?acceptor conjugated polymers based on boron dipyrromethene (BODIPY) as the electron-deficient unit were developed as the electron donor to combine with a NDI-polymer acceptor in order to significantly improve the photoresponse in the NIR region. More importantly, we found that methyl substitution on the BODIPY segment played an important role in charge transport in these polymers. When methyl units were attached to the α-position of BODIPY, the polymer PMBBDT exhibited high-lying energy levels, improved crystallinity, and dramatically high hole mobility compared to the polymer PBBDT without methyl substitution. Consequently, the power conversion efficiencies (PCEs) could be enhanced from 0.32% for PBBDT- to 5.8% for PMBBDT-based all-PSCs, and the photoresponse covered from 300 to 900 nm. Our results demonstrate that methyl-substituted BODIPY-based conjugated polymers are promising candidates to solve the NIR absorption issue in NDI polymers and, therefore, can be potentially used to further boost the PCEs of all-PSCs similar with organic solar cells based on NIR-fused ring electron acceptors.
关键词： Boron dipyrromethene,Methyl substitution,Conjugated polymers,Near-infrared absorption,All-polymer solar cells
更新于2025-09-11 14:15:04
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Highly Efficient Indoor Organic Solar Cells by Voltage Losses Minimization through Fine-tuning of Polymer Structures
摘要： Herein we report a detailed study on the optoelectronic properties, photovoltaic performance, structural conformation, morphology variation, charge carrier mobility and recombination dynamics in bulk heterojunction (BHJ) solar cells comprising of a series of donor-acceptor (D-A) conjugated polymers as electron donors based on benzodithiophene (BDT) and 5,8-bis(5-bromothiophen-2-yl)-6,7-difluoro-2,3-bis(3-(octyloxy)phenyl)quinoxaline as a function of the BDT’s thienyl substitution (alkyl (WF3), alkylthio (WF3S) and fluoro (WF3F)). It is manifested the synergistic positive effects of the fluorine substituents on the minimization of the bimolecular recombination losses, the reduction of the series resistances (RS), the increment of the shunt resistances (RSh), the suppression of the trap-assisted recombination losses, the balanced charge transport, the finer nanoscale morphology and the deeper highest occupied molecular orbital (EHOMO) versus the alkyl- and alkylthio- substituents. According to these findings, WF3F:[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) based-organic photovoltaic (OPV) device is a scarce example that feature a high power conversion efficiency (PCE) of 17.34% under 500 lx indoor LED light with a high open-circuit voltage (VOC) of 0.69 V, due to the suppression of the voltage losses and a PCE of 9.44% at 1-sun (100 mW/cm2) conditions, simultaneously.
关键词： Series and Shunt resistances,Coherence length,Conjugated polymers,Wide-angle X-ray scattering,Organic photovoltaic devices,Recombination losses,Indoor lighting conditions
更新于2025-09-11 14:15:04