| 1. |
- Kattge, Jens, et al.
(author)
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TRY plant trait database - enhanced coverage and open access
- 2020
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In: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Journal article (peer-reviewed)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 2. |
- Saygili, Yasemin, et al.
(author)
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Effect of Coordination Sphere Geometry of Copper Redox Mediators on Regeneration and Recombination Behavior in Dye-Sensitized Solar Cell Applications
- 2018
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In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:9, s. 4950-4962
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Journal article (peer-reviewed)abstract
- The recombination of injected electrons with oxidized redox species and regeneration behavior of copper redox mediators are investigated for four copper complexes, [Cu(dmby)(2)](2+/1+) (dmby = 6,6'-dimethyl-2,2'-bipyridine), [Cu(tmby)(2)](2+/1+) (tmby = 4,4',6,6'- tetramethyl-2,2'-bipyridine), [Cu(eto)(2)](2+/1+) (eto = 4-ethoxy-6,6'-dimethyl-2,2'-bipyridine), and [Cu(dmp)(2)](2+/1+) (dmp = bis(2,9-dimethyl-1,10-phenantroline). These complexes were examined in conjunction with the D5, D35, and D45 sensitizers, having various degrees of blocking moieties. The experimental results were further supported by density functional theory calculations, showing that the low reorganization energies, lambda, of tetra-coordinated Cu(I) species (lambda = 0.31-0.34 eV) allow efficient regeneration of the oxidized dye at driving forces down to approximately 0.1 eV. The regeneration electron transfer reaction is in the Marcus normal regime. However, for Cu(II) species, the presence of 4-tertbutylpyridine (TBP) in electrolyte medium results in penta-coordinated complexes with altered charge recombination kinetics (lambda = 1.23-1.40 eV). These higher reorganization energies lead to charge recombination in the Marcus normal regime instead of the Marcus inverted regime that could have been expected from the large driving force for electrons in the conduction band of TiO2 to react with Cu(II). Nevertheless, the recombination resistance and electron lifetime values were higher for the copper redox species compared to the reference cobalt redox mediator. The DSC devices employing D35 dye with [Cu(dmp)(2)](2+/1+) reached a record value for the open circuit voltage of 1.14 V without compromising the short circuit current density value. Even with the D5 dye, which lacks recombination preventing steric units, we reached 7.5% efficiency by employing [Cu(dmp)(2)](2+/1+) and [Cu(dmby)(2)](2+/1+) at AM 1.5G full sun illumination with open circuit voltage values as high as 1.13 V.
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| 3. |
- Saygili, Yasemin, et al.
(author)
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Liquid State and Zombie Dye Sensitized Solar Cells with Copper Bipyridine Complexes Functionalized with Alkoxy Groups
- 2020
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In: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 124:13, s. 7071-7081
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Journal article (peer-reviewed)abstract
- Copper redox mediators can be employed in dye sensitized solar cells (DSCs) both as liquid electrolytes or as solid state hole transport materials (HTMs). The solid state devices that employ copper complex HTMs can be simply obtained by solvent evaporation in liquid state devices. During this evolution, the copper complex molecules present in the electrolyte solvent slowly aggregate in the pores of the TiO2 film and also close the gap between the TiO2 film and counter electrode. However, the crystallization of the HTM that infiltrated in the mesoscopic TiO2 pores can lead to low photovoltaic performance. In order to prevent this problem, we designed two copper redox mediators [Cu(beto)(2)](1+) (beto = 4,4'-diethoxy-6,6'-dimethyl-2,2'-bipyridine) and [Cu(beto(2Ox))(2)](1+) (beto(2Ox) = 4,4'-bis(2-methoxyethoxy)-6,6'-dimethyl-2,2'-bipyridine) with extended side chains. First, we studied these complexes in liquid state devices in reference to the [Cu(tmby)(2)](2+/1+) complex (tmby = 4,4',6,6'-tetramethyl-2,2'-bipyridine). The solar-to- electrical power conversion efficiencies for liquid state devices were over 10% for all of the complexes by using the organic Y123 dye under 1000 Wm(-2) AM1.5G illumination. However, solid state devices showed significantly diminished charge transport properties and short circuit current density values even though the crystallization was reduced.
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