| 1. |
- An, Jincheng, et al.
(författare)
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Fine-Tuning by Triple Bond of Carbazole Derivative Dyes to Obtain High Efficiency for Dye-Sensitized Solar Cells with Copper Electrolyte
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : NLM (Medline). - 1944-8244 .- 1944-8252. ; 12:41, s. 46397-46405
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Tidskriftsartikel (refereegranskat)abstract
- Three novel dyes consisting of a 5,8,15-tris(2-ethylhexyl)-8,15-dihydro-5H-benzo[1,2-b:3,4-b':6,5-b″]tricarbazole (BTC) electron-donating group and a 4,7-bis(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (BTBT) π-bridge with an anchoring group of phenyl carboxyl acid were synthesized and applied in dye-sensitized solar cells (DSCs).The AJ202 did not contain any triple bonds, the AJ201's ethynyl group was inserted between the BTC and BTBT units, and the AJ206's ethynyl group was introduced between the BTBT moiety and the anchor group. The inclusion and position of the ethynyl linkage in the sensitizer molecules significantly altered the electrochemical properties of these dyes, which can fine-tune the energy levels of the dyes. The best performing devices contained AJ206 as a sensitizer and a Cu(I/II) redox couple, which resulted in a power conversion efficiency (PCE) up to 10.8% under the standard AM 1.5 G illumination, which obtained PCEs higher than those from the devices that contained AJ201 (9.2%) and AJ202 (9.7%) under the same conditions. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the sensitizers were tuned to be well-suited for the Cu(I/II) redox potential and the Fermi level of TiO2. The innovative synthesis of a tricarbazole-based donor moiety in a sensitizer used in combination with a Cu(I/II) redox couple has resulted in relatively high PCEs.
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| 2. |
- Deng, Zijian, et al.
(författare)
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Helical Copper Redox Mediator with Low Electron Recombination for Dye-Sensitized Solar Cells
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 9:15, s. 5252-5259
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Tidskriftsartikel (refereegranskat)abstract
- Redox mediators play a major role in determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Copper complexes are a good option for redox mediators but suffer from electron recombination. The traditional method is to add 4-(tert-butyl)pyridine (TBP) to the electrolyte, which is coordinated with the empty orbit of Ti, thereby slowing down the oxidized mediator's ability to capture electrons. However, this strategy will result in competitive coordination between the redox mediator and TBP, decreasing the stability of the device. In this study, two helical copper(I) complexes are synthesized and applied to TBP-free solar cells. La (1,3-bis(2,2'-bipyridin-6-yloxy)propane) and Lb (1,3-bis[(6'-methyl-2,2'-bipyridin-6-yl)oxy]propane) tend to form double-stranded helicates ([Cu-2(Ln)(2)](2+), n = a, b) rather than mononuclear complexes ([Cu(Ln)](+), n = a, b). To facilitate quantitative analysis of the complexes, Cu(I)Ln and Cu(II)Ln (n = a, b) are used as molecular formulae. (CuLa)-La-I and Cu(I)Lb are characterized by electrospray mass spectroscopy, H-1 NMR spectroscopy, and electrochemistry. J-V measurement shows that both V-oc and J(sc) increase with the increase of (CuLa)-La-I concentration (below 0.1 M), and the best power conversion efficiency is 8.2%. The relationship between Cu(I) concentration and recombination for further study was measured by IMVS.
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| 3. |
- Teng, Chao, et al.
(författare)
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Influence of Triple Bonds as pi-Spacer Units in Metal-Free Organic Dyes for Dye-Sensitized Solar Cells
- 2010
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:25, s. 11305-11313
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Tidskriftsartikel (refereegranskat)abstract
- Four metal-free organic sensitizers (TC101-TC104) with triple bonds in pi-spacers and five reference dyes (TC, TC105, TPC1, D5, and TH208) without triple bonds were applied in dye-sensitized solar cells to study the influence of triple bonds as pi-spacer units on their photoelectrochemical properties and dye-sensitized solar cells (DSCs) performance. Results show that the introduction of triple bond could red-shift the dye's absorption spectrum due to the enhancement of the pi-spacer. However, the spectrum red-shift is much less than that of the introduction of double bond because of more electronegativity of triple bond. The incident photon-to-current conversion efficiency reveals that the electron transfer yield (Phi(nu)(ET)) of DSCs becomes larger with the introduction of triple bond. Electrochemical impedance spectroscopy analysis reveals that the introduction of triple bond almost does not change the electron lifetimes in TiO2 films but decreases the effective diffusion lengths.
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| 4. |
- An, Jincheng, et al.
(författare)
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Thiophene-fused carbazole derivative dyes for high-performance dye-sensitized solar cells
- 2021
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 88
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Tidskriftsartikel (refereegranskat)abstract
- Two novel dyes that are similar in chemical structure, except for different donor units, AJ301and AJ303 were synthesized, characterized and applied as sensitizers in dye-sensitized solar cells (DSSCs). Both dyes exhibited a wide absorption of visible sunlight. The introduction of fused rings on the donor unit of AJ303 presented an appropriate energy level, less recombination and longer electron lifetime to achieve a power conversion efficiency (PCE) of 10.2%, far above that achieved for AJ301 of 6.2% with a [Co(bpy)(3)](2+/3+)-based electrolyte under standard AM1.5G solar irradiation (100 mW cm(-2)). The DSSCs based on AJ303 and AJ301 with [Cu(tmby)(2)](2+/+)-based electrolyte showed a lower PCE of 8.2% and 5.4%, respectively. Therefore, the results indicated that the introduction of a fused-ring in the donor group is a meaningful synthetic strategy to improve the photovoltaic performance.
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| 5. |
- Chen, Ruikui, et al.
(författare)
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Effect of tetrahydroquinoline dyes structure on the performance of organic dye-sensitized solar cells
- 2007
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 19:16, s. 4007-4015
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Tidskriftsartikel (refereegranskat)abstract
- Eleven novel donor acceptor pi-conjugated (D-pi-A) organic dyes have been engineered and synthesized as sensitizers for the application in dye-sensitized solar cells (DSSCs). The electron-donating moieties are substituted tetrahydroquinoline, and the electron-withdrawing parts are cyanoacrylic acid group or cyanovinylphosphonic acid group. Different lengths of thiophene-containing conjugation moieties (thienyl, thienylvinyl, and dithieno[3,2-b;2',3'-d]thienyl) are introduced to the molecules and serve as electron spacers. Detailed investigation on the relationship between the dye structure, photophysical and photoelectrochemical properties, and performance of DSSCs is described here. The bathochromic shift and increase of the molar extinction coefficient of the absorption spectrum are achieved by introduction of larger conjugation moiety. Even small structural changes of dyes result in significant changes in redox energies and adsorption manner of the dyes on TiO2 surface, affecting dramatically the performance of DSSCs based on these dyes. The higher performances are obtained by DSSCs based on the rigid dye molecules, C2 series dyes (Figure 1), although these dyes have lower light absorption abilities relative to other dyes. A maximum solar-to-electrical energy conversion efficiency (eta) of 4.53% is achieved under simulated AM 1.5 irradiation (100 mW/cm(2)) with a DSSC based on C2-2 dye (V-oc = 597 mV, J(sc) = 12.00 mA/cm(2), ff = 0.63). Density functional theory (DFT) calculations have been performed on the dyes, and the results show that electron distribution from the whole molecules to the anchoring moieties occurred during the HOMO-LUMO excitation. The cyanoacrylic acid groups or cyanovinylphosphonic acid group are essentially coplanar with respect to the thiophene units, reflecting the strong conjugation across the thiophene-anchoring groups.
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| 6. |
- Cheng, Ming, et al.
(författare)
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Efficient dye-sensitized solar cells based on an iodine-free electrolyte using L-cysteine/L-cystine as a redox couple
- 2012
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 5:4, s. 6290-6293
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Tidskriftsartikel (refereegranskat)abstract
- A new iodine-free electrolyte based on amino acids L-cysteine/L-cystine as a redox couple has been designed and synthesized. DSSCs fabricated with the conventional I-/I-3(-) redox couple gave efficiencies of 8.1% and 6.3% under optimized experimental conditions based on ruthenium dye, N719, and metal-free organic dye, TH202, respectively. Based on the same dyes, the DSSCs employing the new L-cysteine/L-cystine redox couple showed comparable efficiencies of 7.7% and 5.6%, respectively. However, higher incident-photon-to-electron (IPCE) conversion efficiencies and larger J(sc) values were found for devices with the L-cysteine/L-cystine redox couple than with I-/I-3(-). From an electrochemical impedance spectroscopic study, we found that the charge recombination between the conduction band electrons in the TiO2 film and the electrolyte containing the L-cysteine/L-cystine redox couple is restrained.
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| 7. |
- Gustafsson, Björn, 1948, et al.
(författare)
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Are China's Ethnic Minorities Less Likely to Move?
- 2015
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Ingår i: Eurasian geography and economics. - : Informa UK Limited. - 1538-7216 .- 1938-2863. ; 56:1, s. 44-69
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Tidskriftsartikel (refereegranskat)abstract
- This study uses China’s Inter-Census Survey 2005 to analyse the extent migration behaviour among 14 large ethnic minority groups and the Han majority. Results show that the probability to migrate to all types of destinations varies by province of origin, decreases by age, and in most cases, by expected income at the origin. Furthermore the probability to migrate is found to typically increase by length of education and decrease for females by the number of children. In most cases investigated, a minority ethnicity reduces migration probabilities for people registered in rural China. This is particularly the case for persons belonging to the Uyghur and Tibetan ethnic groups, but also for the Mongolian, Bai, Yao and Tujia groups. In contrast, Korean and Hui have a higher probability of migration than the majority. For people with an urban hukou there are fewer examples that minority ethnicity affects probability to migrate.
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| 8. |
- Gustafsson, Björn, 1948, et al.
(författare)
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Catching Up with the West: Chinese Pathways to the Global Middle Class
- 2020
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Ingår i: The China Journal. - : University of Chicago Press. - 1324-9347 .- 1835-8535. ; 84:1, s. 102-127
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Tidskriftsartikel (refereegranskat)abstract
- Using nationwide household survey data for 2002 and 2013, we investigate how widely Chinese household incomes had caught up to those of the middle class in the developed worldby 2013, the year Xi Jinping came to power. Based on the living standards of the middle-income class in the European Union as our standard of comparison, we estimate that China’s “global middle class” with a similar living standard grew rapidly after 2002, reaching 254 million in 2013. We project that it had grown further to over 450 million by 2018. We describe the characteristics of this middle class, which is predominately urban, largely resides in China’s eastern region, and mainly depends on a wage income. A distinct business middle class exists but is relatively small. Analysis of the chances of attaining a middle-class income reveals the importance of an individual’s circumstances at birth. Parents’ education and occupation matter, and being born with an urban registration (hukou) provides a large advantage. For those born with a rural hukou, the most effective pathways to the middle class are migration and, if possible, obtaining an urban hukou.
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| 9. |
- Gustafsson, Björn, 1948, et al.
(författare)
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Charitable donations by China’s private enterprises
- 2017
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Ingår i: Economic Systems. - : Elsevier BV. - 0939-3625. ; 41:3, s. 456-469
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Tidskriftsartikel (refereegranskat)abstract
- The number of private enterprises in China has grown rapidly, and donations from them are an important source of philanthropy in China today. This paper investigates donations made by private enterprises in 2011 using a survey of data covering all 31 provincial-level units of China. The data show that philanthropy practised by Chinese private enterprises is widespread, but the amounts of donations are unequally distributed. Furthermore, donations are positively related to a company’s profit and in most cases also to the owner’s political participation as expressed in membership in the People’s Congress (PC) as well as the Chinese People’s Political Consultative Conference (CPPCC) at different levels. Donating is also positively related to the presence of a branch of the Communist Party of China and a trade union within the firm. In contrast, there is little support for donations being related to the characteristics of the major owner of the business, such as their gender, age, previous employment experience, party membership or to the governance structure or location of the private firms.
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| 10. |
- Gustafsson, Björn, 1948, et al.
(författare)
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China's Emerging Global Middle Class
- 2017
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Ingår i: The latest changes of income distribution pattern in China - A study on the income distribution of Chinese residents (V). - Beijing, Kina : China Financial & Economic Publishing House.. - 9787509578971 ; , s. 351-385
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Bokkapitel (refereegranskat)abstract
- This chapter seeks to throw new light on the emergence of the Chinese economic middle class using data from the China Household Income Project from 2002, 2007, and 2013. We find that between 2002 and 2013 China’s income distribution was transformed from a pyramid shape, with a majority having rather low income, to a more olive shape, as the middle class emerged. Defining “middle class” as having an income high enough not to be regarded as poor but also low enough not to be regarded as rich if living in a high-income country, we find that the share of China’s population that was middle class was extremely small in 2002, larger but still less than 10 percent in 2007, but it expanded rapidly from 2007 to 2013 to become one-fifth of China’s population, equivalent to roughly 250 million people. China’s middle class remains largely urban and is concentrated in the East; only a small minority of rural households and of rural migrants living in urban areas is middle class. We use simulations to investigate whether the growth of China’s middle class reflects across-the-board income growth versus a redistribution of income to the middle, and to project growth in the size of the middle class to 2020. If all household incomes grow uniformly by 6.5 percent per annum to 2020, then China’s middle class will almost double in size and in 2020 a majority of urban residents, but only 13 percent of rural residents, will be classified as middle class. We examine the characteristics of China’s middle class and find it to be distinctive in terms of its sources of income, location of residence, savings and consumption patterns, education, and Communist Party membership.
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