| 1. |
- 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
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 9:2, s. 461-466
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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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| 2. |
- Aitola, Kerttu, et al.
(författare)
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Carbon nanotube film replacing silver in high-efficiency solid-state dye solar cells employing polymer hole conductor
- 2015
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Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1432-8488 .- 1433-0768. ; 19:10, s. 3139-3144
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Tidskriftsartikel (refereegranskat)abstract
- A semitransparent, flexible single-walled carbon nanotube (SWCNT) film was efficiently used in place of evaporated silver as the counter electrode of a poly(3,4-ethylenedioxythiophene) polymer-based solid-state dye solar cell (SSDSC): the solar-to-electrical energy conversion efficiency of the SWCNT-SSDSC was 4.8 % when it was 5.2 % for the Ag-SSDSC. The efficiency difference stemmed from a 0.1-V difference in the open-circuit voltage, whose reason was speculated to be related to the different recombination processes in the two types of SSDSCs.
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| 3. |
- Aitola, Kerttu, et al.
(författare)
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High Temperature-Stable Perovskite Solar Cell Based on Low-Cost Carbon Nanotube Hole Contact
- 2017
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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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| 4. |
- 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
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 3:4, s. 773-778
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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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| 5. |
- Bagheri, Narjes, et al.
(författare)
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Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon
- 2016
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 194, s. 480-488
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Tidskriftsartikel (refereegranskat)abstract
- The structural properties of annealed nickel oxide and its composites with activated carbon (synthesized via simple precipitation methods) have been addressed using X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption method and scanning electron microscopy. The charge storage properties of materials have also been investigated in three-and two-electrode configurations by means of cyclic voltammetry and galvanostatic charging/discharging in alkaline media. The results are consistent with the view that, depending on a method of preparation, the resulting nickel oxide films may exhibit redox characteristics different from that typically observed for nickel oxide-based materials. It is demonstrated that faradaic-type (redox) reactions, that are typical for battery-like materials, contribute predominantly to the high electrode capacity of 257C g(-1) (at 0.1 A g(-1)). By combining nickel oxide with a capacitive material such as activated carbon within the two-electrode symmetric cell, systems with increased charge-storage capabilities have been obtained. The fact, that the voltage window of nickel oxide-based cell has been broadened positively from 0.6 V to 1 V upon introduction of activated carbon, has also resulted in the increase of the cell's energy and power densities as well.
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| 6. |
- Bai, Xue, et al.
(författare)
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D35-TiO2 nano-crystalline film as a high performance visible-light photocatalyst towards the degradation of bis-phenol A
- 2019
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Ingår i: Chemical Engineering Journal. - : ELSEVIER SCIENCE SA. - 1385-8947 .- 1873-3212. ; 355, s. 999-1010
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Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized photocatalytic suspension system for wastewater treatment is still limited in practice due to particle aggregation, fast charge carrier recombination, poor stability and recycling issue. In this study, we combine TiO2 nano-crystalline film with D35 organic dye to fabricate a new visible-light photocatalyst D35-TiO2, which exhibits excellent visible light absorption. Its transient photocurrent is almost 10 times higher than pure TiO2 under visible light illumination (lambda > 420 nm). Besides the well characterizations of the D35-TiO2 film, e.g., SEM, EDS, TEM, XRD, UV-Vis DRS, XPS, PL and I-T, degradation of bis-phenol A (BPA) is performed as the model reaction to test its photocatalytic activity. Meanwhile, we employ external bias in the reaction system to further enhance the photogenerated charge carrier separation, and improve the photocatalytic efficiency. Under the better experimental conditions of initial BPA concentration (5 mg/L), initial pH (pH 7), external bias (0.25 V) and sensitizer concentration (0.1 mM), BPA is almost completely degraded in 300 min, and the four intermediates are gradually mineralized. The ecotoxicity of BPA also decreases significantly after the photo-degradation. During the reaction, center dot O-2(-) plays a dominant role, meanwhile center dot OH and h(D35)(+) also contribute to the BPA degradation. After five cycles, the D35-TiO2 film still maintain the normal photocatalytic activity. Due to the high stability and recyclability, the D35-TiO2 nano-crystalline film provides a sustainable way for degrading micropollutants in wastewater.
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| 7. |
- Bi, Dongqin, et al.
(författare)
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Unraveling the Effect of PbI2 Concentration on Charge Recombination Kinetics in Perovskite Solar Cells
- 2015
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 2:5, s. 589-594
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Tidskriftsartikel (refereegranskat)abstract
- CH3NH3PbI3 perovskite solar cells have rapidly risen to the forefront of emerging photovoltaic technologies. A solution-based, two-step method was reported to enhance the reproducibility of these solar cells. In this method, first a coating of PbI2 is applied by spin-coating onto a TiO2-coated substrate, followed by a dip in a methylammonium iodide solution, leading to conversion to CH3NH3PbI3. The concentration of PbI2 in the spin-coating solution is a very important factor that affects the infiltration of the perovskite and the amount deposited. The best solar cell performance of 13.9% was obtained by devices prepared using 1.0 M of PbI2 in dimethylformamide. These devices also had the longest electron lifetime and shortest carrier transport time, yielding lowest recombination losses. Rapid quenching of the perovskite emission is found in device-like structures, suggesting reasonably good efficient carrier extraction at the TiO2 interface and quantitative extraction at the spiro-OMeTAD interface.
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| 8. |
- Braumueller, Markus, et al.
(författare)
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Synthesis and characterization of an immobilizable photochemical molecular device for H-2-generation
- 2015
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 44:12, s. 5577-5586
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Tidskriftsartikel (refereegranskat)abstract
- With [Ru-II(bpyMeP)(2)tpphzPtCl(2)](2+) (4) a molecular photocatalyst has been synthesized for visible-light-driven H-2-evolution. It contains the ligand bpyMeP (4,4'-bis(diethyl-(methylene)-phosphonate)-2,2'-bipyridine) with phosphate ester groups as precursors for the highly potent phosphonate anchoring groups, which can be utilized for immobilization of the catalyst on metal-oxide semiconductor surfaces. The synthesis was optimized with regard to high yields, bpyMeP was fully characterized and a solid-state structure could be obtained. Photophysical studies showed that the photophysical properties and the localization of the excited states are not altered compared to similar Ru-complexes without anchoring group precursors. (4) was even more active in homogenous catalysis experiments than [RuII(tbbpy)(2)tpphzPtCl(2)](2+) (6) with tbbpy (4,4'-bis(tbutyl)-2,2'-bipyridine) as peripheral ligands. After hydrolysis (4) was successfully immobilized on NiO, suggesting that an application in photoelectrosynthesis cells is feasible.
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| 9. |
- Cai, Bin, et al.
(författare)
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Boosting the power conversion efficiency of perovskite solar cells to 17.7% with an indolo[3,2-b]carbazole dopant-free hole transporting material by improving its spatial configuration
- 2019
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 7:24, s. 14835-14841
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Tidskriftsartikel (refereegranskat)abstract
- The development of facilely synthesized, dopant-free hole-transporting materials (HTMs) with high efficiency is of great significance for the potential application of perovskite solar cells (PSCs). Herein, we report two novel indolo[3,2-b]carbazole (ICZ) based small molecules obtained via a three-step reaction in a high yield without using expensive catalysts, namely C201 and C202, and further apply them as dopant-free HTMs in PSCs. Compared with C201, C202 contains two additional biphenylamino groups to improve its spatial configuration. It is found that the interplay between the molecular geometry and the aggregation behavior can exert a great influence on the film formation property and thus on the device performance. Strikingly, the champion devices employing C202 as the HTM deliver a much higher PCE of up to 17.7%, which is substantially higher than that of devices containing C201 (8.7%) under 100 mW cm(-2) illumination (AM 1.5G). It is revealed that the C202 capping layer exhibits a more homogeneous and uniform surface morphology as compared to that of C201, which effectively reduces the charge recombination losses and facilitates charge extraction, leading to a much-enhanced photovoltaic performance. This is the first example of ICZ core-based small molecules as dopant-free HTMs in PSCs. Moreover, the PSCs containing C202 as the HTM also exhibited good long-term stability under ambient conditions (40% RH) as compared to devices with doped spiro-OMeTAD, due largely to the hydrophobic nature of C202 which prevented moisture from destroying the perovskite film. This work offers a new avenue for developing cost-effective and stable HTMs for PSCs and other optoelectronic devices.
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| 10. |
- 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
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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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