| 1. |
- Aitola, Kerttu, et al.
(författare)
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High Temperature-Stable Perovskite Solar Cell Based on Low-Cost Carbon Nanotube Hole Contact
- 2017
-
Ingår i: Advanced Materials. - : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 29:17
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Tidskriftsartikel (refereegranskat)abstract
- Mixed ion perovskite solar cells (PSC) are manufactured with a metal-free hole contact based on press-transferred single-walled carbon nanotube (SWCNT) film infiltrated with 2,2,7,-7-tetrakis(N, N-di-p-methoxyphenylamine)-9,90-spirobifluorene (Spiro-OMeTAD). By means of maximum power point tracking, their stabilities are compared with those of standard PSCs employing spin-coated Spiro-OMeTAD and a thermally evaporated Au back contact, under full 1 sun illumination, at 60 degrees C, and in a N-2 atmosphere. During the 140 h experiment, the solar cells with the Au electrode experience a dramatic, irreversible efficiency loss, rendering them effectively nonoperational, whereas the SWCNT-contacted devices show only a small linear efficiency loss with an extrapolated lifetime of 580 h.
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| 2. |
- Jeong, Jaeki, et al.
(författare)
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Pseudo-halide anion engineering for α-FAPbI3 perovskite solar cells
- 2021
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 592:7854, s. 381-385
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Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskites of the general formula ABX(3)-where A is a monovalent cation such as caesium, methylammonium or formamidinium; B is divalent lead, tin or germanium; and X is a halide anion-have shown great potential as light harvesters for thin-film photovoltaics(1-5). Among a large number of compositions investigated, the cubic a-phase of formamidinium lead triiodide (FAPbI(3)) hasemerged as the most promising semiconductor for highly efficient and stable perovskite solar cells(6-9), and maximizing the performance of this material in such devices is of vital importance for the perovskite researchcommunity. Here we introduce an anion engineering concept that uses the pseudo-halide anion formate (HCOO-) to suppress anion-vacancy defects that are present at grain boundaries and at the surface of the perovskite films and to augment the crystallinity of the films. Theresulting solar cell devices attain a power conversion efficiency of 25.6 per cent (certified 25.2 per cent), have long-term operational stability (450 hours) and show intense electroluminescence with external quantum efficiencies of more than 10 per cent. Our findings provide a direct route to eliminate the most abundant and deleterious lattice defects present in metal halide perovskites, providing a facile access to solution-processable films with improved optoelectronic performance.
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| 3. |
- Krebs, Frederik C, et al.
(författare)
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A round robin study of flexible large-area roll-to-roll processed polymer solar cell modules
- 2009
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Ingår i: SOLAR ENERGY MATERIALS AND SOLAR CELLS. - : Elsevier BV. - 0927-0248. ; 93:11, s. 1968-1977
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Tidskriftsartikel (refereegranskat)abstract
- A round robin for the performance of roll-to-roll coated flexible large-area polymer solar-cell modules involving 18 different laboratories in Northern America, Europe and Middle East is presented. The study involved the performance measurement of the devices at one location (Riso DTU) followed by transportation to a participating laboratory for performance measurement and return to the starting location (Riso DTU) for re-measurement of the performance. It was found possible to package polymer solar-cell modules using a flexible plastic barrier material in such a manner that degradation of the devices played a relatively small role in the experiment that has taken place over 4 months. The method of transportation followed both air-mail and surface-mail paths.
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| 4. |
- Valdes, A., et al.
(författare)
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Solar hydrogen production with semiconductor metal oxides: new directions in experiment and theory
- 2012
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 14:1, s. 49-70
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Forskningsöversikt (refereegranskat)abstract
- An overview of a collaborative experimental and theoretical effort toward efficient hydrogen production via photoelectrochemical splitting of water into di-hydrogen and di-oxygen is presented here. We present state-of-the-art experimental studies using hematite and TiO(2) functionalized with gold nanoparticles as photoanode materials, and theoretical studies on electro and photo-catalysis of water on a range of metal oxide semiconductor materials, including recently developed implementation of self-interaction corrected energy functionals.
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| 5. |
- Ahlawat, Paramvir, et al.
(författare)
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A combined molecular dynamics and experimental study of two-step process enabling low-temperature formation of phase-pure alpha-FAPbI3
- 2021
-
Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:17
-
Tidskriftsartikel (refereegranskat)abstract
- It is well established that the lack of understanding the crystallization process in a two-step sequential deposition has a direct impact on efficiency, stability, and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occurring during the two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, x-ray diffraction, and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable alpha phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that result in the low-temperature crystallization of phase-pure alpha-formamidinium lead iodide.
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| 6. |
- Aitola, Kerttu, et al.
(författare)
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Carbon nanotube-based hybrid hole-transporting material and selective contact for high efficiency perovskite solar cells
- 2016
-
Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 9:2, s. 461-466
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a high efficiency perovskite solar cell with a hybrid hole-transporting material-counter electrode based on a thin single-walled carbon nanotube (SWCNT) film and a drop-cast 2,2,7,-7-tetrakis(N, N-di-p-methoxyphenylamine)-9,90-spirobifluorene (Spiro-OMeTAD) hole-transporting material (HTM). The average efficiency of the solar cells was 13.6%, with the record cell yielding 15.5% efficiency. The efficiency of the reference solar cells with spin-coated Spiro-OMeTAD hole-transportingmaterials (HTMs) and an evaporated gold counter electrode was 17.7% (record 18.8%), that of the cells with only a SWCNT counter electrode (CE) without additional HTM was 9.1% (record 11%) and that of the cells with gold deposited directly on the perovskite layer was 5% (record 6.3%). Our results show that it is possible to manufacture high efficiency perovskite solar cells with thin film (thickness less than 1 mu m) completely carbon-based HTMCEs using industrially upscalable manufacturing methods, such as press-transferred CEs and drop-cast HTMs.
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| 7. |
- Anaraki, Elham Halvani, et al.
(författare)
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Low-Temperature Nb-Doped SnO2 Electron-Selective Contact Yields over 20% Efficiency in Planar Perovskite Solar Cells
- 2018
-
Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 3:4, s. 773-778
-
Tidskriftsartikel (refereegranskat)abstract
- Low-temperature planar organic inorganic lead halide perovskite solar cells have been at the center of attraction as power conversion efficiencies go beyond 20%. Here, we investigate Nb doping of SnO2 deposited by a low-cost, scalable chemical bath deposition (CBD) method. We study the effects of doping on compositional, structural, morphological, and device performance when these layers are employed as electron-selective layers (ESLs) in planar-structured PSCs. We use doping concentrations of 0, 1, 5, and 10 mol % Nb to Sn in solution. The ESLs were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and ultraviolet visible spectroscopy. ESLs with an optimum 5 mol % Nb doping yielded, on average, an improvement of all the device photovoltaic parameters with a champion power conversion efficiency of 20.5% (20.1% stabilized).
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| 8. |
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| 9. |
- Cao, Yiming, et al.
(författare)
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11% efficiency solid-state dye-sensitized solar cells with copper(II/I) hole transport materials
- 2017
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Solid-state dye-sensitized solar cells currently suffer from issues such as inadequate nanopore filling, low conductivity and crystallization of hole-transport materials infiltrated in the mesoscopic TiO2 scaffolds, leading to low performances. Here we report a record 11% stable solid-state dye-sensitized solar cell under standard air mass 1.5 global using a hole-transport material composed of a blend of [Cu (4,4',6,6'-tetramethyl-2,2'-bipyridine)2(bis(trifluoromethylsulfonyl)imide)2 and [Cu (4,4',6,6'-tetramethyl-2,2'-bipyridine)2](bis(trifluoromethylsulfonyl)imide). The amorphous Cu(II/I) conductors that conduct holes by rapid hopping infiltrated in a 6.5 mm-thick mesoscopic TiO2 scaffold are crucial for achieving such high efficiency. Using time-resolved laser photolysis, we determine the time constants for electron injection from the photoexcited sensitizers Y123 into the TiO2 and regeneration of the Y123 by Cu(I) to be 25 ps and 3.2 μs, respectively. Our work will foster the development of low-cost solid-state photovoltaic based on transition metal complexes as hole conductors.
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| 10. |
- Ferdowsi, Parnian, et al.
(författare)
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Molecular Engineering of Simple Metal-Free Organic Dyes Derived from Triphenylamine for Dye-Sensitized Solar Cell Applications
- 2020
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 13:1, s. 212-220
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Tidskriftsartikel (refereegranskat)abstract
- Two new metal-free organic sensitizers, L156 and L224, were designed, synthesized, and characterized for application in dye-sensitized solar cells (DSCs). The structures of the dyes contain a triphenylamine (TPA) segment and 4-(benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid as electron-rich and -deficient moieties, respectively. Two different pi bridges, thiophene and 4,8-bis(4-hexylphenyl)benzo[1,2-b:4,5-b ']dithiophene, were used for L156 and L224, respectively. The influence of iodide/triiodide, [Co(bpy)(3)](2+/3+) (bpy=2,2 '-bipyridine), and [Cu(tmby)(2)](2+/+) (tmby=4,4 ',6,6 '-tetramethyl-2,2 '-bipyridine) complexes as redox electrolytes and 18 NR-T and 30 NR-D transparent TiO2 films on the DSC device performance was investigated. The L156-based DSC with [Cu(tmby)(2)](2+/+) complexes as the redox electrolyte resulted in the best performance of 9.26 % and a remarkably high open-circuit voltage value of 1.1 V (1.096 V), with a short-circuit current of 12.2 mA cm(-2) and a fill factor of 0.692, by using 30 NR-D TiO2 films. An efficiency of up to 21.9 % was achieved under a 1000 lx indoor light source, which proved that dye L156 was also an excellent candidate for indoor applications. The maximal monochromatic incident-photon-to-current conversion efficiency of L156-30 NR-D reached up to 70 %.
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| 11. |
- Freitag, Marina, et al.
(författare)
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Copper Phenanthroline as a Fast and High-Performance Redox Mediator for Dye-Sensitized Solar Cells
- 2016
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:18, s. 9595-9603
-
Tidskriftsartikel (refereegranskat)abstract
- The most commonly used redox mediators in dye-sensitized solar cells (DSCs), iodide/triiodide and cobalt trisbipyridine ([Co(bpy)(3)](2+/3+)), were successfully replaced by bis (2,9-dimethy1-1,10-phenanthroline) copp er (I/H) ([Cu(dmp)(2)](1+/2+)). The use of the copper complex based electrolyte led to an exceptionally high photovoltaic performance of 8.3% for LEG4-sensitized TiO2 solar cells, with a remarkably high open-circuit potential of above 1.0 V at 1000 W m(-2) under AM1.5G conditions. The copper complex based redox electrolyte has higher diffusion coefficients and is considerably faster in dye regeneration than comparable cobalt trisbipyridine based electrolytes. A driving force for dye regeneration of only 0.2 eV is sufficient to obtain unit yield, pointing to new possibilities for improvement in DSC efficiencies. The interaction of the excited dye with components of the electrolyte was monitored using steady-state emission measurements and time-correlated single-photon counting (TC-SPC). Our results indicate bimolecular reductive quenching of the excited LEG4 dye by the [Cu(dmp)(2)](2+) complex through a dynamic mechanism. Excited-state dye molecules can readily undergo bimolecular electron transfer with a suitable donor molecule. In DSCs this process can occur when the excited dye is unable to inject electrons into the TiO2. With a high electrolyte concentration the excited dye can be intercepted with an electron from the electrolyte resulting in the reduced state of the dye. Quenching of the reduced dye by the electrolyte competes with electron injection and results in a lower photocurrent. Quenching of excited LEG4 by complexes of [Cu(dmp)(2)](+), [Co(bpy)(3)](2+), and [Co(bpy)(3)](3+) followed a static mechanism, due ground-state dye-quencher binding. Inhibition of unwanted quenching processes by structural modifications may open ways to further increase the overall efficiency.
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| 12. |
- Gusak, Viktoria, 1983, et al.
(författare)
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Diffusion and adsorption of dye molecules in mesoporous TiO2 photoelectrodes studied by indirect nanoplasmonic sensing
- 2013
-
Ingår i: Energy and Environmental Sciences. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 6:12, s. 3627-3636
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we used Hidden Interface-Indirect Nanoplasmonic Sensing (HI-INPS) for real time monitoring of dye impregnation (adsorption-diffusion process) of mesoporous TiO2 electrodes of the kind used in dye-sensitized solar cells. We measured the dye percolation time (i.e. the time to diffuse to the bottom of a TiO2 photoelectrode film) for dye Z907 in a 1 : 1 volume mixture of acetonitrile and tert-butanol for different dye concentrations and for different thicknesses of the TiO2 film, while the total amount of adsorbed dye was simultaneously measured by optical absorption spectroscopy. The experimental data for the impregnation process were analyzed by employing a diffusion-front model, combining diffusion and Langmuir type adsorption, which allows extraction of the effective diffusion coefficient for the system. The latter value is about 15 mu m(2) s(-1) for the combined adsorption-diffusion movement of dye molecules through the TiO2 structure, which is an order of magnitude or more smaller than that for "free" diffusion of dye molecules in bulk solvents.
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| 13. |
- Gusak, Viktoria, 1983, et al.
(författare)
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Time-Resolved Indirect Nanoplasmonic Sensing Spectroscopy of Dye Molecule Interactions with Dense and Mesoporous TiO2 Films
- 2012
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 12:5, s. 2397-2403
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Tidskriftsartikel (refereegranskat)abstract
- Indirect nanoplasmonic sensing (INPS) is an experimental platform exploiting localized surface plasmon resonance (LSPR) detection of processes in nanomaterials, molecular assemblies, and films at the nanoscale. Here we have for the first time applied INPS to study dye molecule adsorption/impregnation of two types of TiO2 materials: thick (10 mu m) mesoporous films of the kind used as photoanode in dye-sensitized solar cells (DSCs), with particle/pore size in the range of 20 nm, and thin (12-70 nm), dense, and flat films. For the thick-film experiments plasmonic Au nanoparticles were placed at the hidden, internal interface between the sensor surface and the mesoporous TiO2. This approach provides a unique opportunity to selectively follow dye adsorption locally in the hidden interface region inside the material and inspires a generic and new type of nanoplasmonic hidden interface spectroscopy. The specific DSC measurement revealed a time constant of thousands of seconds before the dye impregnation front (the diffusion front) reaches the hidden interface. In contrast, dye adsorption on the dense, thin TiO2 films exhibited much faster, Langmuir-like monolayer formation kinetics with saturation on a time scale of order 100 s. This new type of INPS measurement provides a powerful tool to measure and optimize dye impregnation kinetics of DSCs and, from a more general point of view, offers a generic experimental platform to measure adsorption/desorption and diffusion phenomena in solid and mesoporous systems and at internal hidden interfaces.
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| 14. |
- Harms, H. A., et al.
(författare)
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In situ investigation of dye adsorption on TiO2 films using a quartz crystal microbalance with a dissipation technique
- 2012
-
Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 14:25, s. 9037-9040
-
Tidskriftsartikel (refereegranskat)abstract
- Dye adsorption plays a crucial role in dye-sensitized solar cells. Herein, we demonstrate an in situ liquid- phase analytical technique to quantify in real time adsorption of dye and coadsorbates on flat and mesoporous TiO2 films. For the first time, a molar ratio of co-adsorbed Y123 and chenodeoxycholic acid has been measured.
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| 15. |
- Hieulle, Jeremy, et al.
(författare)
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Understanding and decoupling the role of wavelength and defects in light-induced degradation of metal-halide perovskites
- 2024
-
Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 17:1, s. 284-295
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Tidskriftsartikel (refereegranskat)abstract
- Light-induced degradation in metal halide perovskites is a major concern that can potentially hamper the commercialization of perovskite optoelectronic devices. The phenomena viz. ion migration, phase segregation, and defect intolerance are believed to be the factors behind the degradation. However, a detailed mechanistic understanding of how and why light reduces the long-term stability of perovskites is still lacking. Here, by combining multiscale characterization techniques and computational studies, we uncover the role of white light in the surface degradation of state-of-the-art FAPbI3-rich perovskite absorbers (reaching up to 22% PCE in solar cells). We unravel the degradation kinetics and found that white light triggers the chemical degradation of perovskite into secondary phases with higher work function and metallic I–V characteristics. Furthermore, we demonstrate that perovskite degradation is triggered by a combined mechanism involving both light and the presence of defects. We employ surface passivation to understand the role of defect intolerance in the degradation process. Moreover, by using filtered light we uncover the wavelength dependency of the light-induced perovskite degradation. Based on our findings, we infer some strategies for material engineering and device design that can expedite the path toward stable perovskite optoelectronic devices.
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| 16. |
- Hong, Li, et al.
(författare)
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Thiocyanate-Mediated Dimensionality Transformation of Low- Dimensional Perovskites for Photovoltaics
- 2022
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 34:14, s. 6331-6338
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional (2D) hybrid perovskite solar cells have induced widespread research interest owing to their higher stability as compared to three-dimensional (3D) analogues. The photovoltaic performance, however, is still limited. Here, we report a perovskite film dominated by 3D components that are modulated by formamidinium thiocyanate in the 2D PEA(2)FA(3)Pb(4)I(13) perovskite composition. We demonstrate that a dimensionality transformation from a 2D/3D to predominantly 3D perovskite phase in the presence of SCN-based treatment enhances the optical absorption in visible and near-infrared regions. As a result, the power conversion efficiency improved 4.5 times with respect to the control to above 14%. The unencapsulated cell exhibited excellent moisture stability during the shelf lifetime measurement over 70 days under ambient conditions.
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| 17. |
- Koh, Teck Ming, et al.
(författare)
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Influence of 4-tert-Butylpyridine in DSCs with Co-II/III Redox Mediator
- 2013
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:30, s. 15515-15522
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Tidskriftsartikel (refereegranskat)abstract
- The effect of TBP on Co(II/III) redox electrolyte was examined. Photocurrent of the device can be limited in electrolyte with high TBP concentration due to its viscous nature. The higher amount of TBP in electrolyte increases the viscosity of electrolyte and consequently slows down the diffusion of Co-III species. This is a unique observation for Co(II/III) electrolyte which is not observed in I-/I-3(-) electrolyte. An increase in TBP concentration from 0.1 to 0.5 M in a cobalt electrolyte containing 0.1 M Co(bpy)(3)(TFSI)(2) and 0.033 M Co(bpy)(3)(TFSI)(3) produced a 90 mV improvement in open-circuit potential (V-oc). Using electrochemical impedance spectroscopy (EIS), this enhancement could be attributed to the reduced interfacial recombination (33%) as well as a negative shift in the conduction 0 band level of TiO2 (67%). Although the influence of TBP in iodide/triiodide and cobalt-complex electrolytes is similar, the increase of viscosity at relatively high concentration of TBP in Co electrolyte should be taken into consideration in order to accomplish high efficiency DSCs based on Co-complex electrolytes.
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| 18. |
- Koh, Teck Ming, et al.
(författare)
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Photovoltage enhancement from cyanobiphenyl liquid crystals and 4-tert-butylpyridine in Co(II/III) mediated dye-sensitized solar cells
- 2013
-
Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 49:80, s. 9101-9103
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Tidskriftsartikel (refereegranskat)abstract
- Two cyanobiphenyl liquid crystals (LCs), 5CB (4-cyano-4'-pentylbiphenyl) and 8CB (4-cyano-4'-octylbiphenyl), are introduced as additives into Co(II/ III) electrolytes for dye-sensitized solar cells (DSCs). An electrolyte containing a combination of these LCs and 4-tert-butylpyridine (TBP) exhibits higher photovoltage than one with only TBP, resulting in higher power conversion efficiency.
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| 19. |
- Laskova, Barbora, et al.
(författare)
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Electron Kinetics in Dye Sensitized Solar Cells Employing Anatase with (101) and (001) Facets
- 2015
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 160, s. 296-305
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Tidskriftsartikel (refereegranskat)abstract
- Two phase-pure nanocrystalline anatase materials differing in the exposed crystal facets (001) or (101) are studied by electrochemical impedance spectroscopy and by transient photovoltage and photocurrent decay in dye sensitized solar cells. A larger chemical capacitance, indicating larger density of states, is observed for anatase (001). The presence of deep electron traps in (001) nanosheets is further confirmed by optical (UV-Vis) and photoemission (XPS, UPS) spectra. The difference in chemical capacitance indicates a slower diffusion of electrons in the (001) anatase material, but also a higher electron lifetime compared to (101) anatase material. (C) 2015 Elsevier Ltd. All rights reserved.
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| 20. |
- Li, Hairong, et al.
(författare)
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A Simple 3,4-Ethylenedioxythiophene Based Hole-Transporting Material for Perovskite Solar Cells
- 2014
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 53:16, s. 4085-4088
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Tidskriftsartikel (refereegranskat)abstract
- We report a novel electron-rich molecule based on 3,4-ethylenedioxythiophene (H101). When used as the hole-transporting layer in a perovskite-based solar cell, the power-conversion efficiency reached 13.8% under AM 1.5G solar simulation. This result is comparable with that obtained using the well-known hole transporting material 2,2,7,7-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (spiro-OMeTAD). This is the first heterocycle-containing material achieving >10% efficiency in such devices, and has great potential to replace the expensive spiro-OMeTAD given its much simpler and cheaper synthesis.
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| 21. |
- Li, Hairong, et al.
(författare)
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Hole-Transporting Small Molecules Based on Thiophene Cores for High Efficiency Perovskite Solar Cells
- 2014
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 7:12, s. 3420-3425
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Tidskriftsartikel (refereegranskat)abstract
- Two new electron-rich molecules, 2,3,4,5-tetra[4,4'-bis(methoxyphenyl)aminophen-4 ''-yl]-thiophene (H111) and 4,4',5,5'-tetra[4,4'-bis(methoxyphenyl) aminophen-4 ''-yl]-2,2'-bithiophene (H112), which contain thiophene cores with arylamine side groups, are reported. When used as the hole-transporting material (HTM) in perovskite-based solar cell devices, power conversion efficiencies of up to 15.4% under AM 1.5G solar simulation were obtained. This is the highest efficiency achieved with HTMs not composed of 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) and its isomers. Both HTMs, especially H111, have great potential to replace expensive spiro-OMeTAD given their much simpler and less expensive syntheses.
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| 22. |
- Li, Hairong, et al.
(författare)
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New donor-pi-acceptor sensitizers containing 5H-[1,2,5]thiadiazolo [3,4-f]isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione units
- 2013
-
Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 49:24, s. 2409-2411
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Tidskriftsartikel (refereegranskat)abstract
- Two new D-pi-A sensitizers (L101 and L102) incorporating 5H-[1,2,5]thiadiazolo [3,4-f] isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione core structures were synthesized and tested in liquid dye-sensitized solar cells (DSCs). L102 achieved a promising power conversion efficiency (PCE) of 6.2% (AM 1.5, 100 mW cm(-2)).
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| 23. |
- Saygili, Yasemin, et al.
(författare)
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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
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:9, s. 4950-4962
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Tidskriftsartikel (refereegranskat)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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| 24. |
- Syres, Karen L., et al.
(författare)
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Adsorbate-Induced Modification of Surface Electronic Structure: Pyrocatechol Adsorption on the Anatase TiO2 (101) and Rutile TiO2 (110) Surfaces
- 2012
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:44, s. 23515-23525
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Tidskriftsartikel (refereegranskat)abstract
- Photoemission and near-edge X-ray absorption fine structure (NEXAFS) techniques have been used to study the adsorption of pyrocatechol on anatase TiO2 (101) and rutile TiO2 (110) single crystals. Photoemission results suggest the pyrocatechol molecule adsorbs on both surfaces predominantly in a bidentate geometry. Using the searchlight effect, the carbon K-edge NEXAFS spectra recorded for pyrocatechol on anatase TiO2 (101) and rutile TiO2 (110) show the phenyl rings in the pyrocatechol molecule to be oriented at 27 +/- 6 degrees and 2.3 +/- 8 degrees, respectively, from the surface normal. Experimental data and computational models of the pyrocatechol-anatase TiO2 interface indicate the appearance of new occupied and unoccupied states on adsorption due to hybridization between the electronic states of the pyrocatechol molecule and the surface. The atomic character of the new orbitals created facilitates direct photoinjection from pyrocatechol into anatase TiO2 and induces a strong final state effect in the carbon K-edge NEXAFS spectrum.
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| 25. |
- Thorsmolle, Verner K., et al.
(författare)
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Conduction Through Viscoelastic Phase in a Redox-Active Ionic Liquid at Reduced Temperatures
- 2012
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Ingår i: Advanced Materials. - : Wiley. - 1521-4095 .- 0935-9648. ; 24:6, s. 781-781
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Tidskriftsartikel (refereegranskat)abstract
- The phase diagram of the redox active ionic liquid 1-methyl-3-propylimidazolium iodide (PMII) is examined as a function of temperature and iodine concentration. Beyond a threshold concentration of 3.9 M, the formation of higher polyiodides gives rise to a viscoelastic phase upon cooling. Despite of the very high viscosity of such polyiodide-containing PMII melts a strikingly high conductivity is maintained through Grotthuss-type bond exchange and ionic conduction.
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| 26. |
- Thorsmolle, Verner K., et al.
(författare)
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Extraordinarily Efficient Conduction in a Redox-Active Ionic Liquid
- 2011
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Ingår i: ChemPhysChem. - : Wiley. - 1439-7641 .- 1439-4235. ; 12:1, s. 145-149
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Tidskriftsartikel (refereegranskat)abstract
- Iodine added to iodide-based ionic liquids leads to extraordinarily efficient charge transport, vastly exceeding that expected for such viscous systems. Using terahertz time-domain spectroscopy, in conjunction with dc conductivity, diffusivity and viscosity measurements we unravel the conductivity pathways in 1-methyl-3-propylimidazolium iodide melts. This study presents evidence of the Grotthuss mechanism as a significant contributor to the conductivity, and provides new insights into ion pairing processes as well as the formation of polyiodides. The terahertz and transport results are reunited in a model providing a quantitative description of the conduction by physical diffusion and the Grotthuss bond-exchange process. These novel results are important for the fundamental understanding of conduction in molten salts and for applications where ionic liquids are used as charge-transporting media such as in batteries and dye-sensitized solar cells.
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| 27. |
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| 28. |
- Tress, Wolfgang, et al.
(författare)
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The role of the hole-transport layer in perovskite solar cells - reducing recombination and increasing absorption
- 2014
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Ingår i: 2014 IEEE 40TH PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC). - : IEEE. - 9781479943982 ; , s. 1563-1566
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Konferensbidrag (refereegranskat)abstract
- The role of the hole-transport layer (HTL) in CH3NH3PbI3 perovskite solar cells is investigated. It is found that it mainly serves three purposes: First, deposited prior to the gold electrode, it avoids direct contact of the metal electrode with the meso porous TiO2-perovskite layer, and therefore increases the selectivity of the contact. This reduces recombination as evident from an increased open-circuit voltage and a higher luminescence efficiency. Second, the HTL increases the internal quantum efficiency independent of applied voltage and illumination wavelength by reducing (diffusion) losses of charges. Third, due to a smoothing of the TiO2-perovskite mesoscopic layer the HTL increases the reflectivity of the gold electrode, allowing for a second path of the light through the absorber. Both effects result in an enhancement of the short-circuit current density.
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| 29. |
- Wang, Mingkui, et al.
(författare)
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Molecular-Scale Interface Engineering of Nanocrystalline Titania by Co-adsorbents for Solar Energy Conversion
- 2012
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631. ; 5:1, s. 181-187
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Tidskriftsartikel (refereegranskat)abstract
- The use of mixed self-assembled monolayers, combining hydrophobic co-adsorbents with the sensitizer, has been demonstrated to enhance the efficiency of dye-sensitized solar cells (DSCs). Herein, the influence of the anchoring groups of the co-adsorbents on the performance of the DSCs is carefully examined by selecting two model molecules: neohexyl phosphonic acid (NHOOP) and bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP). The effect of these co-adsorbents on the photovoltaic performance (JV curves, incident photon-to-electron conversion efficiency) is investigated. Photoelectron spectroscopy and electrochemical impedance spectroscopy are performed to assess the spatial configuration of adsorbed dye and co-adsorbent molecules. The photoelectron spectroscopy studies indicate that the ligands of the ruthenium complex, containing thiophene groups, point out away from the surface of TiO2 in comparison with the NCS group.
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| 30. |
- Wu, Mingxing, et al.
(författare)
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Economical Pt-Free Catalysts for Counter Electrodes of Dye-Sensitized Solar Cells
- 2012
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 134:7, s. 3419-3428
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Tidskriftsartikel (refereegranskat)abstract
- Three classes (carbides, nitrides and oxides) of nanoscaled early-transition-metal catalysts have been proposed to replace the expensive Pt catalyst as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). Of these catalysts, Cr3C2, CrN, VC(N), VN, TiC, TiC(N), TiN, and V2O3 all showed excellent catalytic activity for the reduction of I-3(-) to I- in the electrolyte. Further, VC embedded in mesoporous carbon (VC-MC) was prepared through in situ synthesis. The I-3(-)/I- DSC based on the VC-MC CE reached a high power conversion efficiency (PCE) of 7.63%, comparable to the photovoltaic performance of the DSC using a Pt CE (7.50%). In addition, the carbide catalysts demonstrated catalytic activity higher than that of Pt for the regeneration of a new organic redox couple of T-2/T-. The T-2/T- DSCs using TiC and VC-MC CEs showed PCEs of 4.96 and 5.15%, much higher than that of the DSC using a Pt CE (3.66%). This work expands the list of potential CE catalysts, which can help reduce the cost of DSCs and thereby encourage their fundamental research and commercial application.
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| 31. |
- Xie, Haibing, et al.
(författare)
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Decoupling the effects of defects on efficiency and stability through phosphonates in stable halide perovskite solar cells
- 2021
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Ingår i: Joule. - : CELL PRESS. - 2542-4351. ; 5:5, s. 1246-1266
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Tidskriftsartikel (refereegranskat)abstract
- Understanding defects is of paramount importance for the development of stable halide perovskite solar cells (PSCs). However, isolating their distinctive effects on device efficiency and stability is currently a challenge. We report that adding the organic molecule 3-phosphonopropionic acid (H3pp) to the halide perovskite results in unchanged overall optoelectronic performance while having a tremendous effect on device stability. We obtained PSCs with similar to 21% efficiency that retain similar to 100% of the initial efficiency after 1,000 h at the maximum power point under simulated AM1.5G illumination. The strong interaction between the perovskite and the H3pp molecule through two types of hydrogen bonds (H center dot center dot center dot I and O center dot center dot center dot H) leads to shallow point defect passivation that has a significant effect on device stability but not on the non-radiative recombination and device efficiency. We expect that our work will have important implications for the current understanding and advancement of operational PSCs.
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| 32. |
- Xu, Bo, et al.
(författare)
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A low-cost spiro[fluorene-9,9 '-xanthene]-based hole transport material for highly efficient solid-state dye-sensitized solar cells and perovskite solar cells
- 2016
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 9:3, s. 873-877
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Tidskriftsartikel (refereegranskat)abstract
- A low-cost spiro[fluorene-9,9'-xanthene] (SFX) based organic hole transport material (HTM) termed X60 was designed and synthesized using a two-step synthetic route. Devices with X60 as HTM showed high power conversion efficiencies (PCEs) amounting to 7.30% in solid-state dye-sensitized solar cells (ssDSCs) and 19.84% in perovskite solar cells (PSCs), under 100 mW cm(-2) AM1.5G solar illumination. To the best of our knowledge, this is the first example of an easily synthesized spiro-structured HTM that shows comparable performance with respect to the well-known HTM Spiro-OMeTAD in both ssDSCs and PSCs. Furthermore, the facile synthesis of X60 from commercially available starting materials makes this HTM very promising for large-scale industrial production in the future.
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