| 1. |
- Adamczak, Desiree, et al.
(författare)
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Influence of synthetic pathway, molecular weight and side chains on properties of indacenodithiophene-benzothiadiazole copolymers made by direct arylation polycondensation
- 2021
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7534 .- 2050-7526. ; 9:13, s. 4597-4606
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Tidskriftsartikel (refereegranskat)abstract
- Atom-economic protocols for the synthesis of poly(indacenodithiophene-alt-benzothiadiazole) (PIDTBT) are presented in which all C-C coupling steps are achieved by direct arylation. Using two different synthetic pathways, PIDTBT copolymers with different side chains (hexylphenyl, octylphenyl, dodecyl, methyl/2-octyldodecylphenyl, 2-octyldodecylphenyl/2-octyldodecylphenyl) and molecular weight (MW) are prepared. Route A makes use of direct arylation polycondensation (DAP) of indacenodithiophene (IDT) and 4,7-dibromo-2,1,3-benzothiadiazole (BTBr2) leading to PIDTBT in high yields, with adjustable MW and without indications for structural defects. Route B starts from a polyketone precursor also prepared by DAP following cyclization. While route B allows introduction of asymmetric side chains at the IDT unit, polymer analogous cyclization gives rise to defect formation. The absorption coefficient of PIDTBT with alkylphenyl side chains made by route A increases with MW. Field-effect hole mobilities around similar to 10(-2) cm(2) V-1 s(-1) are molecular weight-independent, which is ascribed to a largely amorphous thin film morphology. PIDTBT with linear dodecyl side (C12) chains exhibits a bathochromic shift (20 nm), in agreement with theory, and more pronounced vibronic contributions to absorption spectra. In comparison to alkylphenyl side chains, C12 side chains allow for increased order in thin films, a weak melting endotherm and lower energetic disorder, which altogether explain substantially higher field-effect hole mobilities of similar to 10(-1) cm(2) V-1 s(-1).
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| 2. |
- Ali Ahmad, Syed Ossama, et al.
(författare)
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Application of two-dimensional materials in perovskite solar cells: recent progress, challenges, and prospective solutions
- 2021
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 9:40, s. 14065-14092
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Forskningsöversikt (refereegranskat)abstract
- Perovskite solar cells (per-SCs) with high performance and cost-effective solution processing have been the center of interest for researchers in the past decade. Power conversion efficiencies (PCEs) have been gradually improved up to 25.2% with relatively improved stability, which is an unparalleled progress in all generations of solar cell (SC) technology. However, there are still some prevailing challenges regarding the stability and upscaling of these promising devices. Recently, 2D layered materials (LMs) have been extensively explored to overcome the prevailing challenges of poor stability (under moisture, light soaking and high temperature), halide segregation, hysteresis, involvement of toxic materials (i.e., lead), and upscaling of devices. A critical review addressing the recent developments in the use of 2D materials, especially transition metal dichalcogenides (TMDCs), is hence necessary. The development of novel synthesis and deposition techniques including liquid-metal synthesis and ultrasonic assisted spray pyrolysis has offered more efficient fabrication of 2D-LMs with controlled thickness and morphology. Effective functionalization approaches to increase the dispersability of 2D-LMs in non-polar solvents has boosted their potential application in solar cell technology as well. Moreover, compositing 2D TMDCs with suitable organic/inorganic compounds has enabled superior charge kinetics in all functional parts of per-SCs. In addition, newly developed materials such as graphyne and graphdyine along with 2D metal organic frameworks (MOFs) and covalent organic frameworks (COFs) have been employed in per-SCs to achieve PCEs up to 20%. This review summarizes the recent progress and challenges in the application of 2D-LMs in per-SCs and outlines the future pathways to further extend the PCE of per-SCs beyond 25%. This review particularly focuses on 2D-LMs as electrode materials and additives, the underlying charge (electron-hole) transport phenomenon in the functional layers, and their chemical and structural stability.
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| 3. |
- Alsufyani, Maryam, et al.
(författare)
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The effect of aromatic ring size in electron deficient semiconducting polymers for n-type organic thermoelectrics
- 2020
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 8:43, s. 15150-15157
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Tidskriftsartikel (refereegranskat)abstract
- N-type semiconducting polymers have been recently utilized in thermoelectric devices, however they have typically exhibited low electrical conductivities and poor device stability, in contrast to p-type semiconductors, which have been much higher performing. This is due in particular to the n-type semiconductors low doping efficiency, and poor charge carrier mobility. Strategies to enhance the thermoelectric performance of n-type materials include optimizing the electron affinity (EA) with respect to the dopant to improve the doping process and increasing the charge carrier mobility through enhanced molecular packing. Here, we report the design, synthesis and characterization of fused electron-deficient n-type copolymers incorporating the electron withdrawing lactone unit along the backbone. The polymers were synthesized using metal-free aldol condensation conditions to explore the effect of enlarging the central phenyl ring to a naphthalene ring, on the electrical conductivity. When n-doped with N-DMBI, electrical conductivities of up to 0.28 S cm(-1), Seebeck coefficients of -75 mu V K-1 and maximum Power factors of 0.16 mu W m(-1) K-2 were observed from the polymer with the largest electron affinity of -4.68 eV. Extending the aromatic ring reduced the electron affinity, due to reducing the density of electron withdrawing groups and subsequently the electrical conductivity reduced by almost two orders of magnitude.
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| 4. |
- Bai, Sai, et al.
(författare)
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Colloidal metal halide perovskite nanocrystals: synthesis, characterization, and applications
- 2016
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 4:18, s. 3898-3904
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Tidskriftsartikel (refereegranskat)abstract
- Colloidal metal halide perovskite nanocrystals (NCs) have emerged as promising materials for optoelectronic devices and received considerable attention recently. Their superior photoluminescence (PL) properties provide significant advantages for lighting and display applications. In this Highlight, we discuss recent developments in the design and chemical synthesis of colloidal perovskite NCs, including both organic-inorganic hybrid and all inorganic perovskite NCs. We review the excellent PL properties and current optoelectronic applications of these perovskite NCs. In addition, critical challenges that currently limit the applicability of perovskite NCs are discussed, and prospects for future directions are proposed.
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| 5. |
- Barghi, Hamidreza, 1970, et al.
(författare)
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Synthesis of an electroconductive membrane using poly(hydroxymethyl-3,4-ethylenedioxythiophene-co-tetramethylene-N-hydrox yethyl adipamide)
- 2013
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7534 .- 2050-7526. ; 1:39, s. 6347-6354
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of a novel electroconductive membrane (ECM) was studied with the aim of producing an electroconductive membrane (ECM) with low electrical resistance and appropriate mechanical properties. The method was based on copolymerization of a highly electroconductive monomer (hydroxymethyl-3,4-ethylenedioxythiophene) with highly mechanical resistant hydrophilized polyamide 46 (polytetramethylene-N-hydroxyethyl adipamide). Due to the lack of hydroxyl groups, polyamide 46 does not have the tendency to take part in any chemical reactions, therefore prior to copolymerization, PA 46 was hydrophilized with acetaldehyde to create reactive sites, which allowed copolymerization to occur. At the final stage, a very thin layer, 566 nm conductive poly(hydroxymethyl-3,4-ethylenedioxythiophene) homopolymer was localised using in situ plasma polymerization in order to improve the electrical conductivity of the obtained copolymer. The result was an adherent, highly conductive, semi-hydrophilic and flexible ECM. The presence of hydroxyl groups in the final product led to improved hydrophilicity of the conductive membrane with a surface tension of 41 mJ m(-2). The electrical resistance of PA 46 was dramatically reduced after copolymerization, to 202 in dry and 54 k Omega cm(-2) in wet conditions; furthermore, after plasma treatment, this reduction continued to 105 in dry and 2 k Omega cm(-2) in wet conditions. Other parameters such as flux flow, roughness, pore size, pore distribution, contact angle, surface energy and thermal stability of the ECM were also investigated.
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| 6. |
- Barghi, H., et al.
(författare)
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Synthesis of an electroconductive membrane using poly(hydroxymethyl-3,4-ethylenedioxythiophene-co-tetramethylene-N-hydroxyethyl adipamide)
- 2013
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Ingår i: Journal of Materials Chemistry C. - : R S C Publications. - 2050-7526 .- 2050-7534. ; 1:39, s. 6347-6354
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of a novel electroconductive membrane (ECM) was studied with the aim of producing an electroconductive membrane (ECM) with low electrical resistance and appropriate mechanical properties. The method was based on copolymerization of a highly electroconductive monomer (hydroxymethyl-3,4-ethylenedioxythiophene) with highly mechanical resistant hydrophilized polyamide 46 (polytetramethylene-N-hydroxyethyl adipamide). Due to the lack of hydroxyl groups, polyamide 46 does not have the tendency to take part in any chemical reactions, therefore prior to copolymerization, PA 46 was hydrophilized with acetaldehyde to create reactive sites, which allowed copolymerization to occur. At the final stage, a very thin layer, 566 nm conductive poly(hydroxymethyl-3,4-ethylenedioxythiophene) homopolymer was localised using in situ plasma polymerization in order to improve the electrical conductivity of the obtained copolymer. The result was an adherent, highly conductive, semi-hydrophilic and flexible ECM. The presence of hydroxyl groups in the final product led to improved hydrophilicity of the conductive membrane with a surface tension of 41 mJ m−2. The electrical resistance of PA 46 was dramatically reduced after copolymerization, to 202 in dry and 54 kΩ cm−2 in wet conditions; furthermore, after plasma treatment, this reduction continued to 105 in dry and 2 kΩ cm−2 in wet conditions. Other parameters such as flux flow, roughness, pore size, pore distribution, contact angle, surface energy and thermal stability of the ECM were also investigated.
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| 7. |
- Baryshnikov, Gleb V., et al.
(författare)
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Nine-ring angular fused biscarbazoloanthracene displaying a solid state based excimer emission suitable for OLED application
- 2016
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 4:24, s. 5795-5805
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Tidskriftsartikel (refereegranskat)abstract
- A new biscarbazoloanthracene consisting of nine fused aromatic rings, including two pyrrole units, has been obtained in a straightforward and convergent synthesis. Computational chemistry and conformational analysis revealed that the semiconductor's molecule is not planar, the two carbazole moieties being helical twisted from the plane of the anthracene unit. Photophysical and electrochemical measurements showed that this angular fused heteroacene has a low lying HOMO energy level with a wide band gap despite its extended pi-conjugated molecular framework. Based on its relatively low-lying HOMO level, the semiconductor promises a high environmental stability in comparison to other related linear fused acenes and heteroacenes. The biscarbazoloanthracene has been applied as the light emitting layer in a white light emitting diode (WOLED). It is proposed that the white OLED feature is due to dual light emission properties from the active semiconductor layer being based on both the molecular luminescence of the small molecule and a discrete excimer emission made possible by suitable aggregates in the solid state. Noteworthy, this is the first reported example of such a behavior observed in a small molecule heteroacene rather than an oligomer or a polymer.
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| 8. |
- Bazuev, Gennady V., et al.
(författare)
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The effect of manganese oxidation state on antiferromagnetic order in SrMn1-xSbxO3 (0 < x < 0.5) perovskite solid solutions
- 2019
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 7:7, s. 2085-2095
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Tidskriftsartikel (refereegranskat)abstract
- The mixed-valence manganese (Mn3+/Mn4+) solid solution, SrMn1-xSbxO3, was prepared for the first time. Two ranges of solid solutions were found: (1) SrMn1-xSbxO3 (0.025 x 0.09) with monoclinically distorted 6H-SrMnO3 polytype (sp. gr. C/2c) and (2) SrMn1-xSbxO3 (0.17 x 0.50) with a tetragonal unit cell (sp. gr. I4/mcm). Crystal structure refinement using X-ray and neutron powder diffraction data showed that the structure of the monoclinic solid solution consists of corner-sharing octahedra around sites occupied by manganese and antimony ions and face-sharing octahedra around sites occupied by manganese ions only, while the tetragonal solid solution has a random distribution of B-site cations. The presence of long-range antiferromagnetic order with a Neel temperature of about 148 K for SrMn0.80Sb0.20O3 and about 280 K for SrMn0.925Sb0.075O3 was found from the results of DC and AC susceptibility and neutron diffraction experiments at 5 K and 80 K.
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| 9. |
- Benatto, Leandro, et al.
(författare)
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Molecular origin of efficient hole transfer from non-fullerene acceptors : insights from first-principles calculations
- 2019
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 7:39, s. 12180-12193
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Tidskriftsartikel (refereegranskat)abstract
- Due to the strong exciton binding energy (E-b) of organic materials, the energy offset between donor (D) and acceptor (A) materials is essential to promote charge generation in organic solar cells (OSCs). Yet an efficient exciton dissociation from non-fullerene acceptors (NFAs) began to be observed in D/A blends even at very low driving force for hole transfer (Delta H-h). The mechanism behind this efficient photoinduced hole transfer (PHT) remains unclear since current estimates from calculations of isolated molecules indicate that E-b > Delta H-h. Here we rationalize these discrepancies using density functional theory (DFT), the total Gibbs free energy method and the extended Huckel theory (EHT). First, we employed DFT to calculate E-b for NFAs of three representative groups (perylene diimide derivatives, indacenodithiophene and subphthalocyanines) as well as for fullerene acceptors (FAs). Considering isolated molecules in the calculations, we verified that E-b for NFAs is lower than for FAs but still higher than the experimental Delta H-h in which efficient PHT has been observed. Finding the molecular geometry of the excited state, we also obtain that the structural relaxation after photoexcitation tends to further decrease (increase) E-b for NFAs (FAs). This effect helps explain the delayed charge generation measured in some NFA systems. However, this effect is still not large enough for a significant decrease in E-b. We then applied EHT to quantify the decrease of E-b induced by energy levels coupling between stacked molecules in a model aggregate. We then estimated the number of stacked molecules so that E-b approaches Delta H-h's. We found that small NFA aggregates, involving around 5 molecules, are already large enough to explain the experiments. Our results are justified by the low energy barrier to the generation of delocalized states in these systems (especially for the hole delocalization). Therefore, they indicate that molecular systems with certain characteristics can achieve efficient molecular orbital delocalization, which is a key factor to allow an efficient exciton dissociation in low-driving-force systems. These theoretical findings provide a sound explanation to very recent observations in OSCs.
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| 10. |
- Benesperi, Iacopo, et al.
(författare)
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The researcher's guide to solid-state dye-sensitized solar cells
- 2018
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 6:44, s. 11903-11942
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Forskningsöversikt (refereegranskat)abstract
- In order to sustainably support its ever-increasing energy demand, the human society will have to harvest renewable energy wherever and whenever possible. When converting light to electricity, silicon solar cells are the technology of choice to harvest direct sunlight due to their high performance and continuously dropping price. For diffused light and indoor applications, however, silicon is not the material of choice. To power the next gizmo in your smart home, dye-sensitized solar cells (DSCs) are a viable alternative. Made from inexpensive, earth-abundant, and non-toxic materials, DSCs perform best at low light intensity. So far, issues such as leakage of the liquid electrolyte and its corrosive nature have limited the commercialization of this technology. To overcome these limitations, solid-state DSCs (ssDSCs) - in which the liquid electrolyte is replaced by a solid material - have been developed. For many years their efficiencies have been poor, preventing them from being widely employed. In the past six years, however, research efforts have led them to rival with their liquid counterparts. Here, we will review recent advancements in the field of ssDSCs. Every device component will be acknowledged, from metal oxides and new dyes to novel hole transporters, dopants, counter-electrodes and device architectures. After reviewing materials, long-term stability of devices will be addressed, finally giving an insight into the future that awaits this exciting technology.
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