| 1. |
- Benesperi, Iacopo, et al.
(författare)
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Dynamic dimer copper coordination redox shuttles
- 2022
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Ingår i: Chem. - : Elsevier. - 2451-9308 .- 2451-9294. ; 8:2, s. 439-449
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Tidskriftsartikel (refereegranskat)abstract
- Summary Conventional redox mediators based on metal coordination complexes undergo electron transfer through the change in oxidation state of the metal center. However, electron transfer kinetics are offset toward preferred oxidation states when preorganized ligands constrain the reorganization of the coordination sphere. In contrast, we report here on dimeric copper(II/I) redox couples, wherein the extent of oxidation/reduction of two metal centers dictates the dynamic formation of dimer and monomer complexes: the dimeric (Cu(I))2 transitions to monomers of Cu(II). The bis(thiazole/pyrrole)-bipyridine tetradentate ligands stabilize both oxidation states of the unique redox systems. The dynamic dimer redox mediators offer a viable two-electron redox mechanism to develop efficient hybrid solar cells through inhibited recombination and rapid charge transport. Density functional theory calculations reveal inner reorganization energies for single-electron transfer as low as 0.27 eV, marking the dimeric complexes superior redox systems over single complexes as liquid and potentially solid-state electrolytes.
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| 2. |
- Jacobsson, T. Jesper, 1984-, et al.
(författare)
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An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles
- 2022
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Ingår i: Nature Energy. - : Springer Nature. - 2058-7546. ; 7:1, s. 107-115
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Tidskriftsartikel (refereegranskat)abstract
- Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences.
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| 3. |
- Michaels, Hannes, 1994-
(författare)
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A molecular guide to efficient charge transport : Coordination materials for photovoltaic cells
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Emerging solar energy conversion and energy storage technologies play a vital role in solving the present energy crisis and achieving carbon net zero. Currently, they are limited by the use of inefficient, unstable and expensive charge transport materials. The development of new charge transport materials is still far behind the efforts that have been made to develop the light-absorbing or other components. Metalorganic coordination compounds offer unique sets of properties as hybrids between conductive metals and tunable organic molecules. The coordination of the metal centers is crucial to control in order to maximise the solar cell efficiency - or undesired electronic recombination limits the power output. Tetradentate ligands allow copper complexes to dynamically switch between dimers or monomers, pending the oxidation state of the metal ions. The high energy barrier for the reduction of CuII monomers prevents electron transfer across the TiO2|dye|electrolyte interface: Interfacial recombination is reduced and the dye-sensitised solar cells achieve greater photovoltages. Coordination complexes linked into low-dimensional coordination polymers afford charge transport with an electrical conductivity as high as 0.1 S m-1 via band-like conduction at room temperature, needless of cationic dopants. The polymers rapidly extract photoexcited charges from halide perovskite films. 14% power conversion efficiency were recorded from a perovskite solar cell based on a carbon counter electrode. The solar cell stability was much increased compared to heavily doped organic hole conductors. Emerging dye-sensitised solar cells excel especially under ambient conditions, and have been proposed as power sources for dispatched electronic devices (the Internet of things), in place of single-use and difficult-to-recycle batteries. Through tailoring of the optical response and the electrolyte composition, power conversion efficiencies of 37.5% with photovoltages of 1.00 V at 1000 lux (fluorescent lamp) are demonstrated. The increased performance is identified to stem from reduced interfacial recombination by transient photovoltage methods as well as electrochemical impedance spectroscopy. A series of prototype tests underline the feasibility of light harvesters as power sources for electronic devices, executing sophisticated computation tasks such as machine learning. The devices self-optimise their energy consumption; adaptive sleep and small supercapacitors allow to sustain device operation during periods of fluctuating energy availability.
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| 4. |
- Michaels, Hannes, et al.
(författare)
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Assessment of TiO2 Blocking Layers for CuII/I-Electrolyte Dye-Sensitized Solar Cells by Electrochemical Impedance Spectroscopy
- 2022
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 5:2, s. 1933-1941
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Tidskriftsartikel (refereegranskat)abstract
- The TiO2 blocking layer in dye-sensitized solar cells is the most difficult component to evaluate at thicknesses below 50 nm, but it is crucial for the power conversion efficiency. Here, the electrode capacitance of TiO2 blocking layers is tested in aqueous [Fe(CN)6]3–/4– and correlated to the performance of photoanodes in devices based on a [Cu(tmby)2]2+/+ electrolyte. The effects of the blocking layer on electronic recombination in the devices are illustrated with transient photovoltage methods and electrochemical impedance analysis. We have thus demonstrated a feasible and facile method to assess TiO2 blocking layers for the fabrication of dye-sensitized solar cells.
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| 5. |
- Michaels, Hannes, et al.
(författare)
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Copper coordination polymers with selective hole conductivity
- 2022
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 10:17, s. 9582-9591
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Tidskriftsartikel (refereegranskat)abstract
- Emerging technologies in solar energy will be critical in enabling worldwide society in overcoming the present energy challenges and reaching carbon net zero. Inefficient and unstable charge transport materials limit the current emerging energy conversion and storage technologies. Low-dimensional coordination polymers represent an alternative, unprecedented class of charge transport materials, comprised of molecular building blocks. Here, we provide a comprehensive study of mixed-valence coordination polymers from an analysis of the charge transport mechanism to their implementation as hole-conducting layers. Cu-II dithiocarbamate complexes afford morphology control of 1D polymer chains linked by (CuI2X2) copper halide rhombi. Concerted theoretical and experimental efforts identified the charge transport mechanism in the transition to band-like transport with a modeled effective hole mass of 6m(e). The iodide-bridged coordination polymer showed an excellent conductivity of 1 mS cm(-1) and a hole mobility of 5.8 10(-4) cm(2) (V s)(-1) at room temperature. Nanosecond selective hole injection into coordination polymer thin films was captured by nanosecond photoluminescence of halide perovskite films. Coordination polymers constitute a sustainable, tunable alternative to the current standard of heavily doped organic hole conductors.
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| 6. |
- Morritt, G. H., et al.
(författare)
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Coordination polymers for emerging molecular devices
- 2022
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Ingår i: Chemical Physics Reviews. - : American Institute of Physics (AIP). - 2688-4070. ; 3:1
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Forskningsöversikt (refereegranskat)abstract
- Conductive coordination polymers are hybrid materials with the potential to be implemented in the next generation of electronic devices, owing to several desirable properties. A decade ago, only a few scattered examples exhibiting conductivity existed within this class of materials, yet today groups of coordination polymers possess electrical conductivities and mobilities that rival those of inorganic semiconductors. Many currently emerging energy harvesting and storage technologies are limited by the use of inefficient, unstable, and unsustainable charge transport materials with little tunability. Coordination polymers, on the other hand, offer great electrical properties and fine-tunability through their assembly from molecular building blocks. Herein, the structure-function relationship of these building blocks and how to characterize the resulting materials are examined. Solution processability allows devices to step away drastically from conventional fabrication methods and enables cheap production from earth abundant materials. The ability to tune the electrical and structural properties through modifications at the molecular level during the material synthesis stages allows for a large design space, opening the door to a wide spectrum of applications in environmentally friendly technologies, such as molecular wires, photovoltaics, batteries, and sensors. Sustainable, high-performing charge transport materials are crucial for the continued advance of emerging molecular technologies. This review aims to provide examples of how the promising properties of coordination polymers have been exploited to accelerate the development of molecular devices.
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| 7. |
- Sutton, Matthew, et al.
(författare)
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Rapid and Facile Fabrication of Polyiodide Solid-State Dye-Sensitized Solar Cells Using Ambient Air Drying
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:38, s. 43456-43462
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Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized solar cells are promising candidates for low-cost indoor power generation applications. However, they currently suffer from complex fabrication and stability issues arising from the liquid electrolyte. Consequently, the so-called zombie cell was developed, in which the liquid electrolyte is dried out to yield a solid through a pinhole after cell assembly. We report a method for faster, simpler, and potentially more reliable production of zombie cells through direct and rapid drying of the electrolyte on the working electrode prior to cell assembly, using an iodide-triiodide redox couple electrolyte as a basis. These "rapid-zombie" cells were fabricated with power conversion efficiencies reaching 5.0%, which was larger than the 4.5% achieved for equivalent "slow" zombie cells. On a large-area cell of 15.68 cm(2), over 2% efficiency was achieved at 0.2 suns. After 12 months of dark storage, the "rapid-zombie" cells were remarkably stable and actually showed a moderate increase in average efficiencies.
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