| 1. |
- Wu, Zhongbin, et al.
(author)
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Achieving Extreme Utilization of Excitons by an Efficient Sandwich-Type Emissive Layer Architecture for Reduced Efficiency Roll-Off and Improved Operational Stability in Organic Light-Emitting Diodes
- 2016
-
In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:5, s. 3150-3159
-
Journal article (peer-reviewed)abstract
- It has been demonstrated that the efficiency roll-off is generally caused by the accumulation of excitons or charge carriers, which is intimately related to the emissive layer (EML) architecture in organic light-emitting diodes (OLEDs). In this article, an efficient sandwich-type EML structure with a mixed-host EML sandwiched between two single-host EMLs was designed to eliminate this accumulation, thus simultaneously achieving high efficiency, low efficiency roll-off and good operational stability in the resulting OLEDs. The devices show excellent electroluminescence performances, realizing a maximum external quantum efficiency (EQE) of 24.6% with a maximum power efficiency of 105.6 lm W-1 and a maximum current efficiency of 93.5 cd A(-1). At the high brightness of 5 000 cd m(-2), they still remain as high as 23.3%, 71.1 lm W-1, and 88.3 cd A(-1), respectively. And, the device'lifetime is up to 2000 h at initial luminance of 1000 cd m(-2), which is significantly higher than that of compared devices with conventional EML structures. The improvement mechanism is systematically studied by the dependence of the exciton distribution in EML and the exciton quenching processes. It can be seen that the utilization of the efficient sandwich-type EML broadens the recombination zone width, thus greatly reducing the exciton quenching and increasing the probability of the exciton recombination. It is believed that the design concept, provides a new avenue for us to achieve high-performance OLEDs.
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| 2. |
- Wu, Zhongbin, et al.
(author)
-
High-Performance Hybrid White Organic Light-Emitting Diodes with Superior Efficiency/Color Rendering Index/Color Stability and Low Efficiency Roll-Off Based on a Blue Thermally Activated Delayed Fluorescent Emitter
- 2016
-
In: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 26:19, s. 3306-3313
-
Journal article (peer-reviewed)abstract
- Thermally activated delayed fluorescence (TADF)-based white organic light-emitting diodes (WOLEDs) are highly attractive because the TADF emitters provide a promising alternative route to harvest triplet excitons. One of the major challenges is to achieve superior efficiency/color rendering index/color stability and low efficiency roll-off simultaneously. In this paper, high-performance hybrid WOLEDs are demonstrated by employing an efficient blue TADF emitter combined with red and green phosphorescent emitters. The resulting WOLED shows the maximum external quantum efficiency, current efficiency, and power efficiency of 23.0%, 51.0 cd A(-1), and 51.7 lm W-1, respectively. Moreover, the device exhibits extremely stable electroluminescence spectra with a high color rendering index of 89 and Commission Internationale de L'Eclairage coordinates of (0.438, 0.438) at the practical brightness of 1000 cd m(-2). The achievement of these excellent performances is systematically investigated by versatile experimental and theoretical evidences, from which it is concluded that the utilization of a blue-green-red cascade energy transfer structure and the precise manipulation of charges and excitons are the key points. It can be anticipated that this work might be a starting point for further research towards high-performance hybrid WOLEDs.
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| 3. |
- Xu, Kai, et al.
(author)
-
Ground-state electron transfer in all-polymer donor-acceptor heterojunctions
- 2020
-
In: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 19:7, s. 738-744
-
Journal article (peer-reviewed)abstract
- Doping of organic semiconductors is crucial for the operation of organic (opto)electronic and electrochemical devices. Typically, this is achieved by adding heterogeneous dopant molecules to the polymer bulk, often resulting in poor stability and performance due to dopant sublimation or aggregation. In small-molecule donor–acceptor systems, charge transfer can yield high and stable electrical conductivities, an approach not yet explored in all-conjugated polymer systems. Here, we report ground-state electron transfer in all-polymer donor–acceptor heterojunctions. Combining low-ionization-energy polymers with high-electron-affinity counterparts yields conducting interfaces with resistivity values five to six orders of magnitude lower than the separate single-layer polymers. The large decrease in resistivity originates from two parallel quasi-two-dimensional electron and hole distributions reaching a concentration of ∼1013 cm–2. Furthermore, we transfer the concept to three-dimensional bulk heterojunctions, displaying exceptional thermal stability due to the absence of molecular dopants. Our findings hold promise for electro-active composites of potential use in, for example, thermoelectrics and wearable electronics.
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| 4. |
- Chen, Shangzhi, et al.
(author)
-
Conductive polymer nanoantennas for dynamic organic plasmonics
- 2020
-
In: Nature Nanotechnology. - London : Nature Publishing Group. - 1748-3387 .- 1748-3395. ; 15
-
Journal article (peer-reviewed)abstract
- Being able to dynamically shape light at the nanoscale is oneof the ultimate goals in nano-optics1. Resonant light–matterinteraction can be achieved using conventional plasmonicsbased on metal nanostructures, but their tunability is highlylimited due to a fixed permittivity2. Materials with switchablestates and methods for dynamic control of light–matterinteraction at the nanoscale are therefore desired. Here weshow that nanodisks of a conductive polymer can supportlocalized surface plasmon resonances in the near-infraredand function as dynamic nano-optical antennas, with their resonancebehaviour tunable by chemical redox reactions. Theseplasmons originate from the mobile polaronic charge carriersof a poly(3,4-ethylenedioxythiophene:sulfate) (PEDOT:Sulf)polymer network. We demonstrate complete and reversibleswitching of the optical response of the nanoantennasby chemical tuning of their redox state, which modulatesthe material permittivity between plasmonic and dielectricregimes via non-volatile changes in the mobile chargecarrier density. Further research may study different conductivepolymers and nanostructures and explore their usein various applications, such as dynamic meta-optics andreflective displays.
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| 5. |
- Jia, Yanhua, et al.
(author)
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Wearable Thermoelectric Materials and Devices for Self-Powered Electronic Systems
- 2021
-
In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 33:42
-
Research review (peer-reviewed)abstract
- The emergence of artificial intelligence and the Internet of Things has led to a growing demand for wearable and maintenance-free power sources. The continual push toward lower operating voltages and power consumption in modern integrated circuits has made the development of devices powered by body heat finally feasible. In this context, thermoelectric (TE) materials have emerged as promising candidates for the effective conversion of body heat into electricity to power wearable devices without being limited by environmental conditions. Driven by rapid advances in processing technology and the performance of TE materials over the past two decades, wearable thermoelectric generators (WTEGs) have gradually become more flexible and stretchable so that they can be used on complex and dynamic surfaces. In this review, the functional materials, processing techniques, and strategies for the device design of different types of WTEGs are comprehensively covered. Wearable self-powered systems based on WTEGs are summarized, including multi-function TE modules, hybrid energy harvesting, and all-in-one energy devices. Challenges in organic TE materials, interfacial engineering, and assessments of device performance are discussed, and suggestions for future developments in the area are provided. This review will promote the rapid implementation of wearable TE materials and devices in self-powered electronic systems.
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| 6. |
- Jiang, Qinglin, et al.
(author)
-
High Thermoelectric Performance in n-Type Perylene Bisimide Induced by the Soret Effect
- 2020
-
In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 32:45
-
Journal article (peer-reviewed)abstract
- Low-cost, non-toxic, abundant organic thermoelectric materials are currently under investigation for use as potential alternatives for the production of electricity from waste heat. While organic conductors reach electrical conductivities as high as their inorganic counterparts, they suffer from an overall low thermoelectric figure of merit (ZT) due to their small Seebeck coefficient. Moreover, the lack of efficient n-type organic materials still represents a major challenge when trying to fabricate efficient organic thermoelectric modules. Here, a novel strategy is proposed both to increase the Seebeck coefficient and achieve the highest thermoelectric efficiency for n-type organic thermoelectrics to date. An organic mixed ion-electron n-type conductor based on highly crystalline and reduced perylene bisimide is developed. Quasi-frozen ionic carriers yield a large ionic Seebeck coefficient of -3021 mu V K-1, while the electronic carriers dominate the electrical conductivity which is as high as 0.18 S cm(-1)at 60% relative humidity. The overall power factor is remarkably high (165 mu W m(-1)K(-2)), with aZT= 0.23 at room temperature. The resulting single leg thermoelectric generators display a high quasi-constant power output. This work paves the way for the design and development of efficient organic thermoelectrics by the rational control of the mobility of the electronic and ionic carriers.
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| 7. |
- Kiefer, David, 1989, et al.
(author)
-
Double doping of conjugated polymers with monomer molecular dopants
- 2019
-
In: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 18:2, s. 149-155
-
Journal article (peer-reviewed)abstract
- Molecular doping is a crucial tool for controlling the charge-carrier concentration in organic semiconductors. Each dopant molecule is commonly thought to give rise to only one polaron, leading to a maximum of one donor:acceptor charge-transfer complex and hence an ionization efficiency of 100%. However, this theoretical limit is rarely achieved because of incomplete charge transfer and the presence of unreacted dopant. Here, we establish that common p-dopants can in fact accept two electrons per molecule from conjugated polymers with a low ionization energy. Each dopant molecule participates in two charge-transfer events, leading to the formation of dopant dianions and an ionization efficiency of up to 200%. Furthermore, we show that the resulting integer charge-transfer complex can dissociate with an efficiency of up to 170%. The concept of double doping introduced here may allow the dopant fraction required to optimize charge conduction to be halved.
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| 8. |
- Kiefer, David, 1989, et al.
(author)
-
Enhanced n-Doping Efficiency of a Naphthalenediimide-Based Copolymer through Polar Side Chains for Organic Thermoelectrics
- 2018
-
In: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 3:2, s. 278-285
-
Journal article (peer-reviewed)abstract
- N-doping of conjugated polymers either requires a high dopant fraction or yields a low electrical conductivity because of their poor compatibility with molecular dopants. We explore n-doping of the polar naphthalenediimide–bithiophene copolymer p(gNDI-gT2) that carries oligoethylene glycol-based side chains and show that the polymer displays superior miscibility with the benzimidazole–dimethylbenzenamine-based n-dopant N-DMBI. The good compatibility of p(gNDI-gT2) and N-DMBI results in a relatively high doping efficiency of 13% for n-dopants, which leads to a high electrical conductivity of more than 10–1 S cm–1 for a dopant concentration of only 10 mol % when measured in an inert atmosphere. We find that the doped polymer is able to maintain its electrical conductivity for about 20 min when exposed to air and recovers rapidly when returned to a nitrogen atmosphere. Overall, solution coprocessing of p(gNDI-gT2) and N-DMBI results in a larger thermoelectric power factor of up to 0.4 μW K–2 m–1 compared to other NDI-based polymers.
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| 9. |
- Li, Zaifang, et al.
(author)
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A Free-Standing High-Output Power Density Thermoelectric Device Based on Structure-Ordered PEDOT:PSS
- 2018
-
In: Advanced Electronic Materials. - : Wiley-VCH Verlagsgesellschaft. - 2199-160X. ; 4:2
-
Journal article (peer-reviewed)abstract
- A free-standing high-output power density polymeric thermoelectric (TE) device is realized based on a highly conductive (approximate to 2500 S cm(-1)) structure-ordered poly(3,4-ethylenedioxythiophene):polystyrene sulfonate film (denoted as FS-PEDOT:PSS) with a Seebeck coefficient of 20.6 mu V K-1, an in-plane thermal conductivity of 0.64 W m(-1) K-1, and a peak power factor of 107 mu W K-2 m(-1) at room temperature. Under a small temperature gradient of 29 K, the TE device demonstrates a maximum output power density of 99 +/- 18.7 mu W cm(-2), which is the highest value achieved in pristine PEDOT:PSS based TE devices. In addition, a fivefold output power is demonstrated by series connecting five devices into a flexible thermoelectric module. The simplicity of assembling the films into flexible thermoelectric modules, the low out-of-plane thermal conductivity of 0.27 W m(-1) K-1, and free-standing feature indicates the potential to integrate the FS-PEDOT:PSS TE modules with textiles to power wearable electronics by harvesting human bodys heat. In addition to the high power factor, the high thermal stability of the FS-PEDOT:PSS films up to 250 degrees C is confirmed by in situ temperature-dependent X-ray diffraction and grazing incident wide angle X-ray scattering, which makes the FS-PEDOT:PSS films promising candidates for thermoelectric applications.
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| 10. |
- Liu, Jian, et al.
(author)
-
Amphipathic Side Chain of a Conjugated Polymer Optimizes Dopant Location toward Efficient N-Type Organic Thermoelectrics
- 2021
-
In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 33
-
Journal article (peer-reviewed)abstract
- There is no molecular strategy for selectively increasing the Seebeck coefficient without reducing the electrical conductivity for organic thermoelectrics. Here, it is reported that the use of amphipathic side chains in an n-type donor-acceptor copolymer can selectively increase the Seebeck coefficient and thus increase the power factor by a factor of approximate to 5. The amphipathic side chain contains an alkyl chain segment as a spacer between the polymer backbone and an ethylene glycol type chain segment. The use of this alkyl spacer does not only reduce the energetic disorder in the conjugated polymer film but can also properly control the dopant sites away from the backbone, which minimizes the adverse influence of counterions. As confirmed by kinetic Monte Carlo simulations with the host-dopant distance as the only variable, a reduced Coulombic interaction resulting from a larger host-dopant distance contributes to a higher Seebeck coefficient for a given electrical conductivity. Finally, an optimized power factor of 18 mu W m(-1) K-2 is achieved in the doped polymer film. This work provides a facile molecular strategy for selectively improving the Seebeck coefficient and opens up a new route for optimizing the dopant location toward realizing better n-type polymeric thermoelectrics.
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| 11. |
- Liu, Yanfeng, et al.
(author)
-
Mo1.33C MXene-Assisted PEDOT:PSS Hole Transport Layer for High-Performance Bulk-Heterojunction Polymer Solar Cells
- 2020
-
In: ACS APPLIED ELECTRONIC MATERIALS. - : AMER CHEMICAL SOC. - 2637-6113. ; 2:1, s. 163-169
-
Journal article (peer-reviewed)abstract
- Here, we report the usage of two-dimensional MXene, Mo1.33C-assisted poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as an efficient hole transport layer (HTL) to construct high-efficiency polymer solar cells. The composite HTLs are prepared by mixing Mo1.33C and PEDOT:PSS aqueous solution. The conventional devices based on Mo1.33C:PEDOT:PSS exhibit an average power conversion efficiency (PCE) of 9.2%, which shows a 13% enhancement compared to the reference devices. According to the results from hole mobilities, charge extraction probabilities, steady-state photoluminescence, and atomic force microscopy, the enhanced PCE can be ascribed to the improved charge transport and extraction properties of the HTL, along with the morphological improvement of the active layer on top. This work clearly demonstrates the feasibility to combine advantages of Mo1.33C MXene and PEDOT:PSS as the promising HTL in organic photovoltaics.
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| 12. |
- Shi, Yongqiang, et al.
(author)
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Thiazole Imide-Based All-Acceptor Homopolymer with Branched Ethylene Glycol Side Chains for Organic Thermoelectrics
- 2022
-
In: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 61:51
-
Journal article (peer-reviewed)abstract
- n-Type semiconducting polymers with high thermoelectric performance remain challenging due to the scarcity of molecular design strategy, limiting their applications in organic thermoelectric (OTE) devices. Herein, we provide a new approach to enhance the OTE performance of n-doped polymers by introducing acceptor-acceptor (A-A) type backbone bearing branched ethylene glycol (EG) side chains. When doped with 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI), the A-A homopolymer PDTzTI-TEG exhibits n-type electrical conductivity (sigma) up to 34 S cm(-1) and power factor value of 15.7 mu W m(-1) K-2. The OTE performance of PDTzTI-TEG is far greater than that of homopolymer PBTI-TEG (sigma=0.27 S cm(-1)), indicating that introducing electron-deficient thiazole units in the backbone further improves the n-doping efficiency. These results demonstrate that developing A-A type polymers with EG side chains is an effective strategy to enhance n-type OTE performance.
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| 13. |
- Shin, Young-hun, et al.
(author)
-
Synthesis and Aggregation Behavior of a Glycolated Naphthalene Diimide Bithiophene Copolymer for Application in Low-Level n-Doped Organic Thermoelectrics
- 2020
-
In: Macromolecules. - : AMER CHEMICAL SOC. - 0024-9297 .- 1520-5835. ; 53:13, s. 5158-5168
-
Journal article (peer-reviewed)abstract
- The synthesis of a naphthalene diimide bithiophene copolymer P(EO-NDIT2) with branched, base-stable, and purely ether-based side chains is presented. Stille polycondensation leads to high molecular weights that are limited by methyl transfer and eventually T2 homocouplings. While extensive solution aggregation hampers molecular weight determination by conventional methods, NMR spectroscopy allows identification of both T2- (H and methyl) and NDI-related (methyl) end groups, enabling the determination of absolute number average molecular weights larger than M-n,M- NMR similar to 100 kg/mol. Solvent- and temperature-dependent aggregation in solution is investigated by NMR and UV-vis spectroscopy. These results are used for solution doping of P(EONDIT2) with N-benzimidazole-based n-dopants. Spin coating from heated chlorobenzene solutions and using 4-(2,3-dihydro-1,3dimethyl-1H-benzoimidazol-2-yl)-N,N-diisopropylaniline (N-DiPrBI) as the dopant leads to homogeneous films with highest conductivities up to 10(-2) S/cm. Generally, N-DiPrBI concentrations as low as similar to 5 wt % are sufficient to increase conductivity by orders of magnitude. Strikingly, maximum power factors up to 0.11 mu W/mK(2), although limited by conductivity, are achieved for the highest molar mass sample at a low dopant concentration of 2 wt % N-DiPrBI only.
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| 14. |
- Stegerer, Dominik, 1988, et al.
(author)
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Organogels from Diketopyrrolopyrrole Copolymer Ionene/Polythiophene Blends Exhibit Ground-State Single Electron Transfer in the Solid State
- 2022
-
In: Macromolecules. - : American Chemical Society (ACS). - 1520-5835 .- 0024-9297. ; 55:12, s. 4979-4994
-
Journal article (peer-reviewed)abstract
- Acceptor copolymers with low lowest unoccupied molecular orbital (LUMO) energy levels are key materials for organic electronics. In the present work, quaternization of pyridine-flanked diketopyrrolopyrrole (PyDPPPy) is used to lower the LUMO energy level of the resulting monomer (MePyDPPPy) by as much as 0.7 eV. The drastically changed electronic properties of MePyDPPPy hinder a second methylation step even in an excess of trimethyloxonium tetrafluoroborate and thereby give access to the asymmetric functionalization of N-heterocycle-flanked DPP building blocks. The corresponding n-type polymeric ionene PMePyDPPPyT2 with bithiophene as comonomer forms thixotropic organogels with the p-type polythiophene P(g42T-TT), indicative of specific cross-interactions between this couple of copolymers. Gelation of polymer blend solutions, which is absent for other couples of p-type/ n-type polymers, is of general interest for (co)processing and orientation of different electronic polymers simultaneously into films or filaments. Detailed optical and electronic characterization reveals that films processed from organogels exhibit ground-state electron transfer (GSET) enabled by suitably positioned highest occupied molecular orbital (HOMO) and LUMO energy levels of P(g42T-TT) (-4.07 eV) and PMePyDPPPyT2 (-4.20 eV), respectively. Furthermore, molecular interactions related to gelation and GSET do not appear to significantly influence the morphology of the polymer blend films.
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| 15. |
- Sun, Hengda, et al.
(author)
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Complementary Logic Circuits Based on High-Performance n-Type Organic Electrochemical Transistors
- 2018
-
In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 30:9
-
Journal article (peer-reviewed)abstract
- Organic electrochemical transistors (OECTs) have been the subject of intense research in recent years. To date, however, most of the reported OECTs rely entirely on p-type (hole transport) operation, while electron transporting (n-type) OECTs are rare. The combination of efficient and stable p-type and n-type OECTs would allow for the development of complementary circuits, dramatically advancing the sophistication of OECT-based technologies. Poor stability in air and aqueous electrolyte media, low electron mobility, and/or a lack of electrochemical reversibility, of available high-electron affinity conjugated polymers, has made the development of n-type OECTs troublesome. Here, it is shown that ladder-type polymers such as poly(benzimidazobenzophenanthroline) (BBL) can successfully work as stable and efficient n-channel material for OECTs. These devices can be easily fabricated by means of facile spray-coating techniques. BBL-based OECTs show high transconductance (up to 9.7 mS) and excellent stability in ambient and aqueous media. It is demonstrated that BBL-based n-type OECTs can be successfully integrated with p-type OECTs to form electrochemical complementary inverters. The latter show high gains and large worst-case noise margin at a supply voltage below 0.6 V.
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| 16. |
- Sun, Hengda, et al.
(author)
-
n-Type organic electrochemical transistors: materials and challenges
- 2018
-
In: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 6:44, s. 11778-11784
-
Journal article (peer-reviewed)abstract
- Organic electrochemical transistors (OECTs) have emerged as an enabling technology for the development of a variety of applications ranging from digital logic circuits to biosensors and artificial synapses for neuromorphic computing. To date, most of the reported OECTs rely on the use of p-type (hole transporting) conducting and semiconducting polymers as the channel material, while electron transporting (n-type) OECTs are yet immature, thus precluding the realization of advanced complementary circuitry. In this highlight, we review and discuss recent achievements in the area of n-type OECTs, in particular targeting recently reported n-type channel materials and how these have enabled a considerable advancement of OECT circuit capabilities. Further, the critical challenges currently limiting the performance of n-channel OECTs are summarized and discussed, setting material design guidelines for the next generation n-type and complementary OECTs.
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| 17. |
- Volkov, Anton V., et al.
(author)
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Asymmetric Aqueous Supercapacitor Based on p- and n-Type Conducting Polymers
- 2019
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 2:8, s. 5350-5355
-
Journal article (peer-reviewed)abstract
- We demonstrated an asymmetric aqueous supercapacitor made of p- and n-type conducting polymer electrodes. We used the high electron affinity (EA) n-type polymer poly(benzimidazobenzophenanthroline) (BBL) as the anode conducting material, and the low ionization potential (IP) p-type polar polythiophene p(g(4)2T-T) as the cathode material. EA(BBL) matches IPp(g42T-T), enabling the fabrication of all-organic asymmetric p/n-supercapacitors that function in aqueous electrolytes. The devices operate in a voltage window up to 1 V, yielding areal capacitances of 90 mF cm(-2) and specific capacitances of 33 F g(-1) as well as excellent cycling stability with almost 100% capacitance retention over 10 000 cycles.
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| 18. |
- Wang, Suhao, et al.
(author)
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A Chemically Doped Naphthalenediimide-Bithiazole Polymer for n-Type Organic Thermoelectrics
- 2018
-
In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 30:31
-
Journal article (peer-reviewed)abstract
- The synthesis of a novel naphthalenediimide (NDI)-bithiazole (Tz2)-based polymer [P(NDI2OD-Tz2)] is reported, and structural, thin-film morphological, as well as charge transport and thermoelectric properties are compared to the parent and widely investigated NDI-bithiophene (T2) polymer [P(NDI2OD-T2)]. Since the steric repulsions in Tz2 are far lower than in T2, P(NDI2OD-Tz2) exhibits a more planar and rigid backbone, enhancing p-p chain stacking and intermolecular interactions. In addition, the electron-deficient nature of Tz2 enhances the polymer electron affinity, thus reducing the polymer donor-acceptor character. When n-doped with amines, P(NDI2OD-Tz2) achieves electrical conductivity (approximate to 0.1 S cm(-1)) and a power factor (1.5 mu W m(-1) K-2) far greater than those of P(NDI2OD-T2) (0.003 S cm(-1) and 0.012 mu W m(-1) K-2, respectively). These results demonstrate that planarized NDI-based polymers with reduced donor-acceptor character can achieve substantial electrical conductivity and thermoelectric response.
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| 19. |
- Wang, Suhao, et al.
(author)
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Thermoelectric Properties of Solution-Processed n-Doped Ladder-Type Conducting Polymers
- 2016
-
In: Advanced Materials. - : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 28:48, s. 10764-
-
Journal article (peer-reviewed)abstract
- Ladder-type “torsion-free” conducting polymers (e.g., polybenzimidazobenzophenanthroline (BBL)) can outperform “structurally distorted” donor–acceptor polymers (e.g., P(NDI2OD-T2)), in terms of conductivity and thermoelectric power factor. The polaron delocalization length is larger in BBL than in P(NDI2OD-T2), resulting in a higher measured polaron mobility. Structure–function relationships are drawn, setting material-design guidelines for the next generation of conducting thermoelectric polymers.
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| 20. |
- Xing, Yi, et al.
(author)
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Integrated opposite charge grafting induced ionic-junction fiber
- 2023
-
In: Nature Communications. - : NATURE PORTFOLIO. - 2041-1723. ; 14:1
-
Journal article (peer-reviewed)abstract
- The emergence of ionic-junction devices has attracted growing interests due to the potential of serving as signal transmission and translation media between electronic devices and biological systems using ions. Among them, fiber-shaped iontronics possesses a great advantage in implantable applications owing to the unique one-dimensional geometry. However, fabricating stable ionic-junction on curved surfaces remains a challenge. Here, we developed a polyelectrolyte based ionic-junction fiber via an integrated opposite charge grafting method capable of large-scale continuous fabrication. The ionic-junction fibers can be integrated into functions such as ionic diodes and ionic bipolar junction transistors, where rectification and switching of input signals are implemented. Moreover, synaptic functionality has also been demonstrated by utilizing the fiber memory capacitance. The connection between the ionic-junction fiber and sciatic nerves of the mouse simulating end-to-side anastomosis is further performed to realize effective nerve signal conduction, verifying the capability for next-generation artificial neural pathways in implantable bioelectronics. Ionic-junction devices are difficult to integrate with fiber-shaped tissues like nerves and muscles for applications in implantable bioelectronics due to their large size and bulk structure. Authors realize here easy to implant fiber-shaped iontronics through an integrated opposite charge grafting process, enabling the construction of ionic logic gates and artificial neural pathways.
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| 21. |
- Xu, Kai, et al.
(author)
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On the Origin of Seebeck Coefficient Inversion in Highly Doped Conducting Polymers
- 2022
-
In: Advanced Functional Materials. - : Wiley-V C H Verlag GMBH. - 1616-301X .- 1616-3028. ; 32:20
-
Journal article (peer-reviewed)abstract
- A common way of determining the majority charge carriers of pristine and doped semiconducting polymers is to measure the sign of the Seebeck coefficient. However, a polarity change of the Seebeck coefficient has recently been observed to occur in highly doped polymers. Here, it is shown that the Seebeck coefficient inversion is the result of the density of states filling and opening of a hard Coulomb gap around the Fermi energy at high doping levels. Electrochemical n-doping is used to induce high carrier density (>1 charge/monomer) in the model system poly(benzimidazobenzophenanthroline) (BBL). By combining conductivity and Seebeck coefficient measurements with in situ electron paramagnetic resonance, UV-vis-NIR, Raman spectroelectrochemistry, density functional theory calculations, and kinetic Monte Carlo simulations, the formation of multiply charged species and the opening of a hard Coulomb gap in the density of states, which is responsible for the Seebeck coefficient inversion and drop in electrical conductivity, are uncovered. The findings provide a simple picture that clarifies the roles of energetic disorder and Coulomb interactions in highly doped polymers and have implications for the molecular design of next-generation conjugated polymers.
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| 22. |
- Yang, Chiyuan, et al.
(author)
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A high-conductivity n-type polymeric ink for printed electronics
- 2021
-
In: Nature Communications. - : Nature Research. - 2041-1723. ; 12:1
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Journal article (peer-reviewed)abstract
- Conducting polymers, such as the p-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), have enabled the development of an array of opto- and bio-electronics devices. However, to make these technologies truly pervasive, stable and easily processable, n-doped conducting polymers are also needed. Despite major efforts, no n-type equivalents to the benchmark PEDOT:PSS exist to date. Here, we report on the development of poly(benzimidazobenzophenanthroline):poly(ethyleneimine) (BBL:PEI) as an ethanol-based n-type conductive ink. BBL:PEI thin films yield an n-type electrical conductivity reaching 8Scm(-1), along with excellent thermal, ambient, and solvent stability. This printable n-type mixed ion-electron conductor has several technological implications for realizing high-performance organic electronic devices, as demonstrated for organic thermoelectric generators with record high power output and n-type organic electrochemical transistors with a unique depletion mode of operation. BBL:PEI inks hold promise for the development of next-generation bioelectronics and wearable devices, in particular targeting novel functionality, efficiency, and power performance. The development of n-type conductive polymer inks is critical for the development of next-generation opto-electronic devices that rely on efficient hole and electron transport. Here, the authors report an alcohol-based, high performance and stable n-type conductive ink for printed electronics.
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