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Tuning the Cross-Linker Crystallinity of a Stretchable Polymer Semiconductor
摘要： The cross-linking of conjugated polymers has been demonstrated to be an effective strategy to improve its elastic properties to give deformable semiconductors for plastic electronics. While there have been extensive studies of the structural requirements of the polymer host for good film ductility, no work to date has focused on the relevance of the structural design or chemistry of these cross-linker additives. In this study, urethane groups and tertiary carbon atoms are inserted into the alkyl backbone of perfluorophenyl azide-based cross-linkers to investigate the importance of cross-linker crystallinity with respect to polymer morphology and hence mechanical and electrical properties. Linear cross-linkers with hydrogen bonding from urethane groups readily phase separate and recrystallize in the polymer network to form cross-linked domains that obstruct the strain distribution of the polymer film. Branch cross-linkers with tertiary carbon on the other hand form an evenly cross-linked network in the polymer blend stemming from excellent miscibility and show a 4-fold increase in fracture strain. Furthermore, a stable hole mobility of 0.2 cm2 V?1 s?1 is achieved up to ε = 100%, and a stable hole mobility of 0.1 cm2 V?1 s?1 after 2000 cycles of ε = 25% on fully stretchable organic field-effect transistors.
关键词： cross-linking,deformable semiconductors,cross-linker crystallinity,electrical properties,polymer morphology,elastic properties,plastic electronics,conjugated polymers,mechanical properties
更新于2025-09-23 15:21:21
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Multicolor emission from non-conjugated polymers based on a single switchable boron chromophore
摘要： Multicolor emissive and responsive materials are highly attractive due to their potential applications in various fields, and polymers are preferred for their good processability and high stability. Herein, we report a series of new polymers based on a methacrylate monomer containing a switchable boron chromophore. In spite of the unconjugated nature, interestingly, the homopolymers from this monomer display rare multicolor fluorescence in solution that is highly dependent on the degree of polymerization (DP). With an ascending DP, the local concentration of the chromophore increases, leading to a higher propensity for switching the blue emitting tricoordinate boron chromophore to the red emitting tetracoordinate one. The homopolymers also display temperature and solvent-dependent emission colour change. Furthermore, pure white-light emission could be achieved in various solvents by precisely tuning the homopolymer molecular weight, or in films/solid state by copolymerizing the emissive boron monomer with non-emissive monomers in an appropriate ratio.
关键词： Multi-responsiveness,Non-conjugated Polymer,Single Chromophore,White Light Emission,Multicolor Emission
更新于2025-09-23 15:21:21
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p-Doping Poly(3-hexylthiophene) in Solvent Mixtures
摘要： One method to improve the conductivity of conjugated polymers, like poly(3-hexylthiophene) (P3HT), is to “chemically dope” them analogous to inorganic materials. One electron acceptor that has been used in tandem to p-doped P3HT is 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), and recently there has been much interest in the nature of the interactions between F4TCNQ and P3HT in the solution phase. To date, however, there are few reports that investigate the behavior of F4TCNQ-doped P3HT in binary solvent mixtures. The study reported herein is an investigation of F4TCNQ-doped P3HT in mixtures of chloroform (CF) with dichloromethane (DCM) or acetonitrile (AcN), wherein variations in the doping efficiency in these mixtures are observed using UV–vis absorption, Raman, and electron paramagnetic resonance spectroscopic techniques. The contrasting solubility and charge transfer behavior of F4TCNQ-doped P3HT in CF:DCM and CF:AcN show that judicious selection of solvent mixtures may be exploited to improve the doping efficiency and solution processability of p-doped P3HT dispersions.
关键词： dispersions,charge transfer,conjugated polymers,self-assembly
更新于2025-09-23 15:21:21
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Unraveling Doping Capability of Conjugated Polymers for Strategic Manipulation of Electric Dipole Layer toward Efficient Charge Collection in Perovskite Solar Cells
摘要： Developing electrical organic conductors is challenging because of the difficulties involved in generating free charge carriers through chemical doping. To devise a novel doping platform, the doping capabilities of four designed conjugated polymers (CPs) are quantitatively characterized using an AC Hall-effect device. The resulting carrier density is related to the degree of electronic coupling between the CP repeating unit and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), and doped PIDF-BT provides an outstanding electrical conductivity, exceeding 210 S cm?1, mainly due to the doping-assisted facile carrier generation and relatively fast carrier mobility. In addition, it is noted that a slight increment in the electron-withdrawing ability of the repeating unit in each CP diminishes electronic coupling with F4-TCNQ, and severely deteriorates the doping efficiency including the alteration of operating doping mechanism for the CPs. Furthermore, when PIDF-BT with high doping capability is applied to the hole transporting layer, with F4-TCNQ as the interfacial doping layer at the interface with perovskite, the power conversion efficiency of the perovskite solar cell improves significantly, from 17.4% to over 20%, owing to the ameliorated charge-collection efficiency. X-ray photoelectron spectroscopy and Kelvin probe analyses verify that the improved solar cell performance originates from the increase in the built-in potential because of the generation of electric dipole layer.
关键词： conjugated polymers,conducting polymers,doping,molecular electronics,solar cells
更新于2025-09-23 15:21:01
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High-Efficiency Perovskite Quantum Dot Solar Cells Benefiting from a Conjugated Polymer-Quantum Dot Bulk Heterojunction Connecting Layer
摘要： In this work, we reported an efficient and universal method to fabricate perovskite quantum dot (PQD) solar cells with enhanced efficiency. Through dissolving optimal amount conjugated polymers in PQD matrix solution to fabricate a polymer-QD bulk heterojunction hybrid layer located at PQD/hole transporting layer (HTL) interfaces, the resultant solar cell devices exhibit significantly enhanced short-circuit current density and efficiency. In-depth characterizations indicate that adding optimal conjugated polymer into the PQD film can effectively reduce pin-holes, resulting in more efficient interfacial charge transfer and decreased carrier recombination loss. More importantly, it shows that the highest occupied molecular orbital (HOMO) energy level of the conjugated polymer is crucial for achieving improved carrier transport at the PQD/HTL interfaces. Through rational selection of conjugated polymers, we achieved the best power conversion efficiency of ~14% and 13.2% for CsPbI3 and FAPbI3 PQD based solar cells respectively, situating the forefront of all reported PQD solar cells. These findings would provide insights into well controlling the organic-inorganic interfaces to improve photovoltaic devices.
关键词： interfacial modification,solar cells,perovskite quantum dot,bulk heterojunction,conjugated polymer
更新于2025-09-23 15:21:01
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Theoretical and Conceptual Framework to Design Efficient Dye-Sensitized Solar Cells (DSSCs): Molecular Engineering by DFT Method
摘要： Herein, eight new donor-p-acceptor organic dyes namely M1–M8 have been theoretically investigated for their potential in optoelectronic properties. The M1–M8 were designed through structural modi?cation of p-conjugated bridge of reference reported molecule IC2. The designed molecules contain Indolo[3,2,1-jk]carbazole as core donor unit and end capped cyanoacrylic acid as acceptor unit. DFT and TDDFT calculations using B3LYP, CAM-B3LYP, xB97XD and M062X functional were performed to evaluate the photophysical and photovoltaic properties. Results indicate that HOMO–LUMO energy gaps in M1–M8 have been found smaller than IC2. Among all, M7 is a material with lowest energy gap 2.61 eV, red shifted absorption wavelength value 436 nm. Results of the calculated redox potential of the ground state, vertical excitation energy of the dye, oxidation potential of the dye in the excited state, free energy change for electron injection, dye regeneration and open circuit photovoltage and light harvesting ef?ciency indicates that p-bridges in M1–M8 would show better power conversion ef?ciency than IC2. Especially, dye M7 with p-bridge 5-(thiazol-5yl)thiazole is found to be the most promising candidate for highly effective DSSCs properties. This theoretical framework may provide new ways for experimentalists to design high-performance DSSCs materials for optoelectronic applications.
关键词： Molecular modeling,p-conjugated linkers,Indolo[3,2,1-jk]carbazole,DSSCs
更新于2025-09-23 15:21:01
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Nona??Conjugated Polymer Based on Polyethylene Backbone as Dopanta??Free Holea??Transporting Material for Efficient and Stable Inverted Quasia??2D Perovskite Solar Cells
摘要： Novel non-conjugated polymer based on polyethylene backbone, PVCz-OMeTPA with suitable energy levels, good hole mobility as well as excellent film-forming ability assisting the formation of high-quality perovskite films, is developed as efficient dopant-free hole-transporting materials (HTMs) for inverted quasi-2D perovskite solar cells (PSCs). Quasi-2D PSCs using ultra-thin, dopant-free PVCz-OMeTPA as HTM exhibited excellent power conversion efficiency of 17.22% and long-term environmental stability.
关键词： low-cost,quasi-2D perovskite solar cells,main-chain non-conjugated polymer,dopant-free hole-transporting materials
更新于2025-09-23 15:21:01
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Nonlinear Optics || Molecular Origin of the Nonlinear Optical Response
摘要： In Chapter 3, we presented a general quantum-mechanical theory of the nonlinear optical susceptibility. This calculation was based on time-dependent perturbation theory and led to explicit predictions for the complete frequency dependence of the linear and nonlinear optical susceptibilities. Unfortunately, however, these quantum-mechanical expressions are typically far too complicated to be of use for practical calculations. In this chapter we review some of the simpler approaches that have been implemented to develop an understanding of the nonlinear optical characteristics of various materials. Many of these approaches are based on understanding the optical properties at the molecular level. We also present brief descriptions of the nonlinear optical characteristics of conjugated polymers, chiral molecules, and liquid crystals.
关键词： chiral molecules,nonlinear optical susceptibility,liquid crystals,quantum-mechanical theory,conjugated polymers,time-dependent perturbation theory
更新于2025-09-23 15:21:01
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The Balance between Energy Transfer and Exciton Separation in Ternary Organic Solar Cells with Two Conjugated Polymer Donor
摘要： Ternary strategy as a straightforward way for organic solar cells (OSCs) to improve the device performance attracts many interests in the field. The ternary strategy usually focuses on processing the third light-absorbing material owning a complementary absorption to the binary system. However, studying the third component with similar absorption spectra to the binary counterpart is equally essential to understand the in-depth mechanism of the performance improvement from the third component. In this work, we filled up this blank and derived a type of ternary device consisting of two conjugated polymer donor materials of PTB7-Th and PffBT4T-2OD and non-fullerene acceptor material of IEICO-4F. The average PCE value of the optimized ternary device reached 12.1%, which is around 16% higher than its PTB7-Th:IEICO-4F binary counterpart. Even the third component of PffBT4T-2OD containing a similar absorption spectrum with PTB7-Th, it was found that the Jsc increase contributes to the primary performance enhancement. Further investigations indicate that the Jsc increase in the optimized ternary device mainly came from the improved light absorption ability, current extraction process, charge transport process, and suppressed non-radiative recombination. Moreover, there is a balance found between the exciton separation process and the energy transfer process when optimizing ternary blend ratios. The optimized ternary device is suspected to reach this balance point and thus exhibits the enhancement in device performance. Morphology investigation reveals that the addition of PffBT4T-2OD can tune the morphology and increase the crystallinity in the active layer. The optimized ternary blend shows a well-mixed donor and acceptor morphology with small domain size and slightly increased crystallization, which further explained its best device performance.
关键词： non-fullerene,energy transfer,exciton separation,organic solar cells,ternary,crystallization,conjugated polymer
更新于2025-09-23 15:21:01
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4H-pyranylidene-based small push-pull chromophores: Synthesis, structure, electronic properties and photovoltaic evaluation
摘要： The synthesis and electrochemical and optical characterizations of four new 4H-pyranylidene-based push-pull molecules are reported herein as well as their evaluation as donor materials for organic photovoltaics. Studied systems exhibit good absorption properties and appropriate LUMO levels for a photoinduced electron transfer to C60. Bilayer organic solar cells fabricated from these new donors and C60 as the acceptor gave photocurrent however with low power conversion efficiencies. As shown by X-ray diffraction and theoretical calculations, titled molecules present a twisted structure which may prevent the formation of suitable π-π contacts between adjacent molecules hence explaining their low photovoltaic performance.
关键词： Push-pull systems,Small conjugated molecules,4H-pyranylidene,Organic photovoltaics
更新于2025-09-23 15:21:01