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Dithiazolylthienothiophene Bisimide-Based ??-Conjugated Polymers: Improved Synthesis and Application to Organic Photovoltaics as P-Type Semiconductor
摘要： Dithiazolylthienothiophene bisimide (TzBI) is a promising building unit for donor-acceptor π-conjugated polymers due to its strong electron-deficiency and high coplanarity. We previously reported a TzBI-based π-conjugated polymer functioned as n-type semiconductor in organic photovoltaic cells. However, a critical subject was that the molecular weight of the polymer was not sufficiently high. It is also important to investigate the possibility of TzBI-based polymers as the p-type semiconductor. In this study, we show that a new synthetic approach gave a new TzBI-based polymer with an improved molecular weight relative to the previously reported polymer. Further, having a co-building unit with a more electron-rich nature, the polymer functioned as p-type semiconductor in organic photovoltaic cells when the PC61BM was used as n-type material. This study shows that TzBI is a versatile building unit for π-conjugated polymers that can be used in organic electronic devices.
关键词： Imide,π-Conjugated polymers,Organic photovoltaics
更新于2025-09-23 15:19:57
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Efficient Polymer Solar Cells Employing Solutiona??Processed Conjugated Polyelectrolytes with Differently Charged Side Chains
摘要： Poly(6-(4,7-dimethyl-2H-benzo[d][1,2,3]triazol-2-yl)-N,N,N-trimethylhexan-1 aminium iodide) (PBTz-TMAI) and poly(sodium 4-(4,7-dimethyl-2H-benzo[d][1,2,3]triazol-2-yl)butane-1-sulfonate) (PBTz-SO3Na) based on the same benzotriazole-conjugated backbone but with ammonium and sulfonated side chains are designed and synthesized through side-chain functionalization and Yamamoto polymerization, respectively, and are used as the cathode interlayers in fullerene- and non-fullerene-based polymer solar cells. The interfacial modification of PBTz-TMAI and PBTz-SO3Na onto the active layer achieves good energy alignment at cathode electrodes and optimized exciton-dissociation efficiency from the active layer. Consequently, the power conversion efficiencies (PCEs) of 7.8% and 9.6% are obtained for the fullerene PTB7:PC71BM-based and non-fullerene PBDB-T:ITIC-based polymer solar cells (PSCs) with PBTz-SO3Na interlayer. The PCS devices based on PTB7:PC71BM and PBDB-T:ITIC active layers with PBTz-TMAI interlayer achieved a remarkably improved performance with PCEs of 8.2% and 10.2%, respectively.
关键词： cathode interlayers,polymer solar cells,conjugated polyelectrolytes
更新于2025-09-23 15:19:57
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Trap-Assisted Triplet Emission in Ladder-Polymer-Based Light-Emitting Diodes
摘要： The charge transport and recombination in light-emitting diodes (LEDs) based on a methyl-substituted poly(p-phenylene) ladder polymer (Me-LPPP) are investigated. The transport is characterized by a high room-temperature hole mobility of 2 × 10?8 m2 V?1 s?1 combined with anomalously strong electron trapping. Their electroluminescence (EL) spectrum is characterized by a blue singlet emission, a broad green featureless peak, and a yellow-orange triplet emission. The voltage dependence of the EL spectrum and negative contribution to the capacitance indicate that the triplet-emission is of trap-assisted nature, consistent with the strong electron trapping. Consequently, the color purity of the blue emissive Me-LPPP polymer LEDs can be strongly improved using trap dilution.
关键词： conjugated polymers,charge transport,light-emitting diodes
更新于2025-09-23 15:19:57
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High-performance green light-emitting diodes based on MAPbBr <sub/>3</sub> with ??-conjugated ligand
摘要： The morphology, crystal size, and trap density of perovskite films significantly affect the luminescent properties of perovskite light-emitting diodes (PeLEDs). Recently, numerous studies have been conducted on ligands that surround the surface of perovskite crystals and passivate the trap sites to improve the performance of PeLEDs. In this study, a 4-aminobenzonitrile (ABN) ligand improved the performance of methylammonium lead bromide (MAPbBr3)-based PeLEDs by reducing the MAPbBr3 crystal size to the nanoscale and reducing the trap density. Moreover, the properties of PeLEDs with ABN were further improved using a surface-modified hole-transport layer (HTL) with a hydrophilic polymer. Finally, a bright green PeLED was fabricated and exhibited the maximum luminance of 3350 cd/m2 with an external quantum efficiency of 8.85%. Therefore, it is believed that the use of proper ligands for the perovskite layer and the optimization of the charge-transport layer have great potential for the development of high-performance PeLEDs.
关键词： methylammonium lead bromide,hydrophilic polymer,conjugated ligand,surface-modified hole-transport layer,perovskite light-emitting diodes,4-aminobenzonitrile
更新于2025-09-23 15:19:57
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Delocalization boosts charge separation in organic solar cells
摘要： Organic solar cells (OSCs) utilizing π-conjugated polymers have attracted widespread interest over the past three decades because of their potential advantages, including low weight, thin film flexibility, and low-cost manufacturing. However, their power conversion efficiency (PCE) has been far below that of inorganic analogs. Geminate recombination of charge transfer excitons is a major loss process in OSCs. This paper reviews our recent progress in using transient absorption spectroscopy to understand geminate recombination in bulk heterojunction OSCs, including the impact of polymer crystallinity on charge generation and dissociation mechanisms in nonfullerene acceptor-based OSCs. The first example of a high PCE with a small photon energy loss is also presented. The importance of delocalization of the charge wave function to suppress geminate recombination is highlighted by this focus review.
关键词： Polymer crystallinity,Power conversion efficiency,Organic solar cells,Transient absorption spectroscopy,Dissociation mechanisms,Photon energy loss,π-conjugated polymers,Charge generation,Nonfullerene acceptor,Geminate recombination
更新于2025-09-23 15:19:57
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A DFT study to probe homo-conjugated norbornylogous bridged spacers in dye-sensitized solar cells: an approach to suppressing agglomeration of dye molecules
摘要： This work reports a sigma-bridged framework as spacers to design new dye-sensitized solar cells. The norbornylogous bridged spacer can avoid p–p aggregation of dye molecules on the semiconductor surface in DSSCs. These sesquinorbornatrienes are known to exhibit electron propagation through the interaction of sigma and p orbitals via through bond (OITB) and through space (OITS) mechanisms. Density functional theory (DFT) calculations performed with these spacers and a modelled simple donor unit like N,N-dimethylamine and cyanoacrylic acid as the anchoring group showed significant results with the requisite optical parameters for DSSCs. The newly designed dyes have shown comparable or better optical properties compared to the reference dye molecule with p-conjugated thiophene spacer units. The DGinjection, VOC and mnormal values calculated for the designed dyes were found to be higher than those of the reference system. The trans-sesquinorbornatriene system spacer (6-D) showed a VOC of 3.3 eV, DGinjection of 2.4 eV and oscillatory strength (f) of 0.96. The total and partial density of states indicates a good communication between the valence and conduction band for the designed dyes. Transition density matrix results suggest that the exciton dissociation in the excited state is sufficiently high to overcome the coulombic attraction of the hole. These results are promising for the design of dye molecules with such scaffolds, to achieve better efficiency and to eliminate one of the major issues with p-spacer units in DSSCs.
关键词： homo-conjugated norbornylogous bridged spacers,dye molecules,DFT study,dye-sensitized solar cells,suppressing agglomeration
更新于2025-09-23 15:19:57
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Ultrathin two-dimensional conjugated metala??organic framework single-crystalline nanosheets enabled by surfactant-assisted synthesis
摘要： Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have recently emerged for potential applications in (opto-)electronics, chemiresistive sensing, and energy storage and conversion, due to their excellent electrical conductivity, abundant active sites, and intrinsic porous structures. However, developing ultrathin 2D c-MOF nanosheets (NSs) for facile solution-processing and integration into devices remains a great challenge, mostly due to unscalable synthesis, low yield, limited lateral size and low crystallinity. Here, we report a surfactant-assisted solution synthesis toward ultrathin 2D c-MOF NSs, including HHB-Cu (HHB=hexahydroxybenzene), HHB-Ni and HHTP-Cu (HHTP=2,3,6,7,10,11-hexahydroxytriphenylene). For the first time, we achieve single-crystalline HHB-Cu(Ni) NSs featured with a thickness of 4-5 nm (~8-10 layers) and a lateral size of 0.25-0.65 μm2, as well as single-crystalline HHTP-Cu NSs with a thickness of ~5.1±2.6 nm (~10 layers) and a lateral size of 0.002-0.02 μm2. Benefiting from the ultrathin feature, the synthetic NSs allow fast ion diffusion and high utilization of active sites. As a proof of concept, when serving as a cathode material for Li-ion storage, HHB-Cu NSs deliver a remarkable rate capability (charge within 3 min) and long-term cycling stability (90% capacity retention after 1000 cycles), superior to the corresponding bulk materials and other reported MOF cathodes.
关键词： Li-ion batteries,Two-dimensional conjugated metal-organic frameworks,electrochemical performance,surfactant-assisted synthesis,ultrathin nanosheets
更新于2025-09-23 15:19:57
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Synthesis of second-order nonlinear optical chromophores with conjugated steric hindrances for electro-optics @850 nm
摘要： Electro-optic materials at the shortwave infrared window (850 nm) of optical fiber is significant for free-space telecommunication and short-distance local area network. However, most of current high-performance organic nonlinear optical chromophores (absorption bandgap ~1.5 eV) are designed for the operation windows of 1310 nm (O band) or 1550 nm (C band), which are not transparent at 850 nm (bandgap ~1.45 eV). The design and synthesis of chromophores for 850 nm is more challenging because regular bandgap engineering to improve microcroscopic nonlinearity (μβ value) might be not available due to the bandgap restriction (optical transparency) @ 850 nm. In this respect, this manuscript utilizes the strategy of suitable site-isolation in molecular engineering to optimize comprehensive performance of chromophores for electro-optics @850 nm. Vilsmeier formylation is facilitated on symmetric or asymmetric donor-π-donor intermediate dyes to form donor-π-acceptor (D-π-A) chromophores C1 and C2 with tuneable conjugated steric hindrance (site-isolator). Without significant red-shift of absorption spectra, conjugated steric hindrance groups contribute to large enhancement of chromophores’ μβ values and ensure optical transparency @ 850 nm. The μβ values of C1 (6706 ? 10-48 esu) and C2 (7279 ? 10-48 esu) with conjugated site-isolation groups are much higher than previously reported chromophores for 850 nm. The structure-property relation reveals that a suitable site-isolator is extremely significant for realizing highly efficient translation of microscopic hyperpolarizability into macroscopic electro-optic coefficients. As a results, electro-optic coefficients of 94 pm/V @ 830 nm are achieved. To the best of our knowledge, this is the highest value for organic electro-optics materials @ 850 nm.
关键词： Electro-optic materials,Vilsmeier formylation,conjugated steric hindrance,site-isolation,nonlinear optical chromophores
更新于2025-09-23 15:19:57
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Xanthene Dye-Functionalized Conjugated Porous Polymers as Robust and Reusable Photocatalysts for Controlled Radical Polymerization
摘要： Photoinduced electron/energy transfer?reversible addition?fragmentation chain transfer (PET?RAFT) polymerization represents a versatile and highly e?cient method for polymerizations of wide-ranging monomer variances upon solar energy harvesting. Although signi?cant progress has been achieved, several drawbacks are still associated with existing photocatalysts, such as toxicity of transition metals, high cost, poor stability, and unavoidable puri?cation procedures because of the photobleaching e?ect, to name a few. Herein, 1,4-diethynylbenzene-linked xanthene dye-conjugated porous polymers (CPPs) have been established as potential heterogenous photocatalysts of PET?RAFT polymerization. With this two-dimensional planar architecture, we demonstrate dual-stimuli toggling of RAFT polymerization using two di?erent external physical manipulations: light “ON”/“OFF” and solution pH “LOW”/“HIGH”. In addition, these CPPs endowed radical polymerizations with various impressive features such as compatibility of diverse monomer formulations, unique oxygen tolerance, and ppm-level catalyst dosage. Demonstrations of chain extension and catalyst recycling further highlight the robustness and performance of this CPP catalyst. Through the study of structure?property relationship using the experimental analyses, we envisage that a series of xanthene dye-functionalized CPPs can be developed as visible light-absorbing organocatalysts rivaling transition-metal photocatalysts.
关键词： PET?RAFT polymerization,visible light-absorbing organocatalysts,xanthene dye-functionalized conjugated porous polymers,dual-stimuli toggling,heterogeneous photocatalysts
更新于2025-09-23 15:19:57
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Composite Interlayer Consisting of Alcohol-Soluble Polyfluorene and Carbon Nanotubes for Efficient Polymer Solar Cells
摘要： We report the synthesis of composite interlayers using alcohol-soluble polyfluorene (ASP)-wrapped single-walled carbon nanotubes (SWNTs) and their application as electron transport layers for efficient organic solar cells. The ASP enables the individual dispersion of SWNTs in solution. The ASP-wrapped SWNT solutions are stable for 54 days without any aggregation or precipitation, indicating their very high dispersion stability. Using the ASP-wrapped SWNTs as a cathode interlayer on zinc oxide nanoparticles (ZnO NPs), a power conversion efficiency of 9.45% is obtained in PTB7-th:PC71BM-based organic solar cells, which is mainly attributed to the improvement in the short circuit current. Performance enhancements of 18% and 17% are achieved compared to those of pure ZnO NPs and ASP on ZnO NPs, respectively. In addition, the composite interlayer is applied to non-fullerene-based photovoltaics with PM6:Y6, resulting in the PCE up to 14.37%. The type of SWNT (e.g., in terms of diameter range and length) is not critical to the improvement in the charge-transport properties. A low density of SWNTs in the film (~1 SWNTs/μm2 for ASP-wrapped SWNTs) has a significant influence on the charge transport in solar cells. The improvement in the performance of the solar cell is attributed to the increased internal quantum efficiency, balanced mobility between electrons and holes, and minimized charge recombination.
关键词： interfacial layers,alcohol-soluble polyfluorene,interlayers,organic solar cells,conjugated polyelectrolytes,Carbon nanotubes,electron transport layers,composites
更新于2025-09-23 15:19:57