| 1. |
- Hudson, Lawrence N, et al.
(author)
-
The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
- 2017
-
In: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 7:1, s. 145-188
-
Journal article (peer-reviewed)abstract
- The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
|
|
| 2. |
- Hudson, Lawrence N., et al.
(author)
-
The PREDICTS database : a global database of how local terrestrial biodiversity responds to human impacts
- 2014
-
In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:24, s. 4701-4735
-
Journal article (peer-reviewed)abstract
- Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups - including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems - ). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.
|
|
| 3. |
- Dissanayake, M. A. K. L., et al.
(author)
-
High-efficiency dye-sensitized solar cells fabricated with electrospun PVdF-HFP polymer nanofibre-based gel electrolytes
- 2023
-
In: Bulletin of Materials Science. - 0973-7669 .- 0250-4707. ; 46:2
-
Journal article (peer-reviewed)abstract
- Poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) electrospun polymer nanofibre-based quasi-solid or gel electrolytes were successfully fabricated by incorporating a liquid electrolyte within the nanofibre membrane. The dye-sensitized solar cells (DSSCs) fabricated with gel and with liquid electrolyte were characterized by photocurrent–voltage measurements and electrochemical impedance spectroscopy measurements. The maximum efficiency (η) of 6.79% was observed for the DSSC fabricated with optimized nanofibre membrane thickness, corresponding to 4 min of electrospinning time. The optimized PVdF-HFP nanofibre gel electrolyte shows an ionic conductivity of 7.16 × 10−3 S cm–1 at 25°C, while the corresponding liquid electrolyte exhibits an ionic conductivity of 11.69 × 10–3 S cm–1 at the same temperature. The open circuit voltage (Voc), short circuit current density (Jsc) and fill factor were recorded as 801.40 mV, 12.70 mA cm–2, and 66.67%, respectively, at an incident light intensity of 100 mW cm–2 with a 1.5 AM filter. The nanofibre gel electrolyte-based cell showed an efficiency of 6.79%, whereas the efficiency of the conventional liquid electrolyte-based cell was 7.28% under the same conditions. Furthermore, nanofibre gel electrolyte-based cells exhibited better stability, maintaining 85.40% of initial efficiency after 120 h. These results show that the optimized, polymer nanofibre-based gel electrolyte can be used successfully to replace the liquid electrolyte in DSSCs without much loss of efficiency but improving the stability while minimizing most of the drawbacks associated with liquid electrolytes.
|
|
| 4. |
- Bandara, T M W J, 1968, et al.
(author)
-
Conductivity behaviour in novel quasi-solid-state electrolyte based on polyacrylonitrile and tetrahexylammonium iodide intended for dye sensitized solar cells
- 2013
-
In: Journal of the National Science Foundation of Sri Lanka. - : Sri Lanka Journals Online (JOL). - 1391-4588 .- 2362-0161. ; 41:3, s. 175-184
-
Journal article (peer-reviewed)abstract
- The conduction of iodide ions in gel polymer electrolytes and the performance of dye sensitized solar cells containing such an electrolyte can be enhanced by incorporating a salt having a bulky cation. In this work, polyacrylonitrile (PAN) and Hex(4)N(+)I(-) based gel electrolytes with ethylene carbonate and propylene carbonate as plasticizers have been studied. The variation of conductivity and molar conductivity with salt concentration has been discussed in order to understand the mechanism of iodide ion conductivity in this system. Out of the various compositions studied, the electrolyte containing 120 % salt with respect to weight of PAN showed the highest conductivity, 2.0 X 10(-3) Scm(-1) at 25 degrees C and a glass transition at - 102.3 degrees C. The electrolytes exhibit predominantly ionic behaviour and because of the bulky cation a negligible cationic transport is shown. A quasi-solid-state dye sensitized solar cell was fabricated employing the optimized gel electrolyte. This cell showed an energy conversion efficiency of 3.1 % and a short circuit current density of 8.1 mAcm(-2) under irradiation of 1000 Wm(-2).
|
|
| 5. |
- Bandara, T M W J, 1968, et al.
(author)
-
Effect of cation size on the performance of dye sensitized nanocrystalline TiO2 solar cells based on quasi-solid state PAN electrolytes containing quaternary ammonium iodides
- 2013
-
In: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 109, s. 609-616
-
Journal article (peer-reviewed)abstract
- The performance of dye sensitized nanocrystalline TiO2 solar cells based on quasi-solid state PAN electrolytes containing a series of six quaternary ammonium iodide salts NH4I, Eth(4)NI, Prop(4)NI, But(4)NI, Pent(4)NI, Hex(4)NI with different cation sizes has been evaluated. Even though the total ionic conductivity decreases with increasing cation size from NH4I to Hex(4)NI, the iodide ion conductivity in the electrolytes increases with cation size. The open circuit photovoltage (V-oc) of the dye sensitized solar cells also increases with cation radius. The efficiency of the DSSCs varies with cation size and exhibits a maximum for Prop(4)NI salt. The short circuit photo current density (J(sc)) follows a similar variation with cation size, suggesting a strong correlation between the cation size dependence of efficiency and J(sc). The DSSC fabricated with tetrapropylammonium iodide exhibited the maximum efficiency of 4.30% with maximum J(sc) of 10.78 mA cm(-2) and a V-oc of 0.746 V. The results have been interpreted on the basis of "the electrolyte effects" where J(sc) is determined essentially by the iodide ion conductivity and "the electrode effects" where the J(sc) and V-oc are determined by the cation adsorption in the dyed TiO2 electrode and resulting electron dynamics at the semiconductor/electrolyte interface. For DSSCs with small cations, electrolyte effects appear to be dominating and rate determining while for DSSCs with larger cations, electrode effects appear to be dominating and rate determining. (C) 2013 Elsevier Ltd. All rights reserved.
|
|
| 6. |
- Bandara, T M W J, 1968, et al.
(author)
-
Tetrahexylammonium iodide containing solid and gel polymer electrolytes for dye sensitized solar cells
- 2012
-
In: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 14, s. 1607-1612
-
Conference paper (peer-reviewed)abstract
- The performance evaluation plays a more and more important role in the modern enterprise management, and the method of evaluation system on enterprise performance is always an important question in the theory and practice. So this paper set up a scientific, reasonable performance evaluation index system which was especially suitable for the small and medium third party logistics enterprise from the four levels of financial, customers, business and innovation. Meanwhile, according to the index system, it gave a performance evaluation with the Chinese access logistics corporation. The results showed that the construction of the index system was reasonable, and the evaluation results also were reliable.
|
|
| 7. |
|
|
| 8. |
- Bandara, T M W J, 1968, et al.
(author)
-
Efficiency enhancement of dye-sensitized solar cells with PAN:CsI:LiI quasi-solid state (gel) electrolytes
- 2014
-
In: Journal of Applied Electrochemistry. - : Springer Science and Business Media LLC. - 1572-8838 .- 0021-891X. ; 44:8, s. 917-926
-
Journal article (peer-reviewed)abstract
- While many attempts have been made in the recent past to improve the power conversion efficiencies of dye-sensitized solar cells (DSSCs), only a few reports can be found on the study of these cells using binary iodides in the gel polymer electrolyte. This paper reports the effect of using a binary mixture of (large and small cation) alkaline salts, in particular CsI and LiI, on the efficiency enhancement in DSSCs with gel polymer electrolytes. The electrolyte with the binary mixture of CsI:LiI = 1:1 (by weight) shows the highest ionic conductivity 2.9 x 10(-3) S cm(-1) at 25 A degrees C. DC polarization measurements showed predominantly ionic behavior of the electrolyte. The density of charge carriers and mobility of mobile ions were calculated using a newly developed method. The temperature dependent behavior of the conductivity can be understood as due to an increase of both the density and mobility of charge carriers. The solar cell with only CsI as the iodide salt gave an energy conversion efficiency of similar to 3.9 % while it was similar to 3.6 % for the cell with only LiI. However, the electrolyte containing LiI:CsI with mass ratio 1:1 showed the highest solar cell performance with an energy conversion efficiency of similar to 4.8 % under the irradiation of one Sun highlighting the influence of the mixed cation on the performance of the cell. This is an efficiency enhancement of 23 %.
|
|
| 9. |
- Bandara, T M W J, 1968, et al.
(author)
-
N719 and N3 dyes for quasi-solid state dye sensitized solar cells - A comparative study using polyacrylonitrile and CsI based electrolytes
- 2016
-
In: Ceylon Journal of Science. - : Sri Lanka Journals Online (JOL). - 2513-230X .- 2513-2814. ; 45:2, s. 61-69
-
Journal article (peer-reviewed)abstract
- Dye sensitized solar cells offer a low cost alternative technology for solar energy harvesting. However, there are long term stability issues connected with these cells due to the liquid electrolytes normally used. Gel or solid polymer electrolytes which do not contain volatile solvents have been used in this investigation in order to alleviate these problems. Two types of solar cells were assembled using a double layered TiO2 film sensitized with two types of dye sensitizers, namely N719 (Ruthenizer 535-bisTBA) and N3 (Ruthenizer 535) in order to compare their performance. Quasi-solid-state electrolytes based on PAN (polyacrylonitrile) as the host polymer and CsI as the iodide salt were prepared by incorporating ethylene carbonate (EC) and propylene carbonate (PC) as plasticizers. The conductivity of the electrolyte was further improved by adding tetrapropylammonium iodide (Pr4NI), 1-methyl 3-propyl imidazolium iodide (MPII) and 4-tert-butylpyridine (4TBP). The incorporation of these additives resulted in 17% enhancement in ionic conductivity. This improved electrolyte was used to fabricate the solar cells with N3 and N719 dyes. The efficiency of the N3 dye based solar cell was 3.85% whereas the efficiency of the N719 dye based solar cell was 4.14% representing a significant efficiency enhancement by 7.53% by the N719 dye. In addition, due to additives the solar cell efficiency has enhanced by 19% compared to the solar cell without any additive.
|
|
| 10. |
- Bandara, T M W J, 1968, et al.
(author)
-
Performance enhancers for gel polymer electrolytes based on LiI and RbI for quasi-solid-state dye sensitized solar cells
- 2016
-
In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:105, s. 103683-103691
-
Journal article (peer-reviewed)abstract
- In this study, the effect of additives (enhancers) on efficiency enhancement in dye sensitized solar cells (DSSCs) containing two series of gel polymer electrolytes, one based on LiI and the other based on RbI have been systematically studied. Polyacrylonitrile (PAN) was used as the host polymer while the performance enhancers used in each case were tetrapropylammoniumiodide (Pr4NI), the ionic liquid 1-methyl-3-propyl imidazolium iodide (MPII) and 4-tert-butylpyridine (4TBP) respectively. Appropriate amounts of the selected enhancers were incorporated one by one, in LiI based and RbI based gel electrolytes. The incorporation of Pr4NI and MPII led to an increase in conductivity of the electrolyte, while 4TBP showed a decrease in conductivity. The maximum conductivity of 3.85 mS cm(-1) at room temperature was shown by the RbI based-series while for the LiI based series the maximum conductivity was 2.95 mS cm(-1). Each of these electrolytes with respective additives was used to fabricate quasi-solid state DSSCs. For the DSSCs based on the LiI containing series, a significant short circuit current density (J(sc)) enhancement (161%) from 3.65 to 9.54 mA cm(-2) was observed due to the addition of Pr4NI. This J(sc) value further increased to 9.7 mA cm(-2) due to the addition of MPII and 4TBP. For the DSSCs with corresponding Rb based electrolytes with all three additives, the highest J(sc) value obtained was 11.5 mA cm(-2). The incorporation of the three additives Pr4NI, MPII and 4TBP collectively enhanced the open circuit voltages and the efficiencies of both LiI and RbI containing quasi-solid state DSSCs. Another important finding from this work is that rarely used RbI containing electrolytes exhibit superior DSSC performance compared to more frequently used LiI based electrolytes. Hence, RbI appears to be a better candidate compared to LiI to fabricate gel polymer electrolytes for DSSCs in general. The three additives have contributed to a remarkable efficiency enchantment in DSSCs by 449.3% for the LiI based electrolyte and by 35.7% for the RbI based electrolyte.
|
|
