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Publications (10 of 20) Show all publications
Abdelhamid, H. N., El-Zohry, A. M., Cong, J., Thersleff, T., Karlsson, K. M., Kloo, L. & Zou, X. (2019). Towards implementing hierarchical porous zeolitic imidazolate frameworks in dye-sensitized solar cells. Royal Society Open Science, 6(7), Article ID 190723.
Open this publication in new window or tab >>Towards implementing hierarchical porous zeolitic imidazolate frameworks in dye-sensitized solar cells
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2019 (English)In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 6, no 7, article id 190723Article in journal (Refereed) Published
Abstract [en]

A one-pot method for encapsulation of dye, which can be applied for dye-sensitized solar cells (DSSCs), and synthesis of hierarchical porous zeolitic imidazolate frameworks (ZIF-8), is reported. The size of the encapsulated dye tunes the mesoporosity and surface area of ZIF-8. The mesopore size, Langmuir surface area and pore volume are 15 nm, 960-1500 m(2). g(-1) and 0.36-0.61 cm(3). g(-1), respectively. After encapsulation into ZIF-8, the dyes show longer emission lifetimes (greater than 4-8-fold) as compared to the corresponding non-encapsulated dyes, due to suppression of aggregation, and torsional motions.

Place, publisher, year, edition, pages
Royal Society Publishing, 2019
Keywords
zeolitic imidazolate frameworks, hierarchical Porous ZIF-8, dye encapsulation, dye-sensitized solar cells, photophysical properties, emission lifetime
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-257464 (URN)10.1098/rsos.190723 (DOI)000479146300079 ()31417762 (PubMedID)2-s2.0-85070743581 (Scopus ID)
Note

QC 20190830

Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2019-08-30Bibliographically approved
Zhang, F., Cong, J., Li, Y., Bergstrand, J., Liu, H., Cai, B., . . . Sun, L. (2018). A facile route to grain morphology controllable perovskite thin films towards highly efficient perovskite solar cells. Nano Energy, 53, 405-414
Open this publication in new window or tab >>A facile route to grain morphology controllable perovskite thin films towards highly efficient perovskite solar cells
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2018 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 53, p. 405-414Article in journal (Refereed) Published
Abstract [en]

Perovskite photovoltaics have recently attracted extensive attention due to their unprecedented high power conversion efficiencies (PCEs) in combination with primitive manufacturing conditions. However, the inherent polycrystalline nature of perovskite films renders an exceptional density of structural defects, especially at the grain boundaries (GBs) and film surfaces, representing a key challenge that impedes the further performance improvement of perovskite solar cells (PSCs) and large solar module ambitions towards commercialization. Here, a novel strategy is presented utilizing a simple ethylammonium chloride (EACl) additive in combination with a facile solvent bathing approach to achieve high quality methyammonium lead iodide (MAPbI3) films. Well-oriented, micron-sized grains were observed, which contribute to an extended carrier lifetime and reduced trap density. Further investigations unraveled the distinctively prominent effects of EACl in modulating the perovskite film quality. The EACl was found to promote the perovskite grain growing without undergoing the formation of intermediate phases. Moreover, the EACl was also revealed to deplete at relative low temperature to enhance the film quality without compromising the beneficial bandgap for solar cell applications. This new strategy boosts the power conversion efficiency (PCE) to 20.9% and 19.0% for devices with effective areas of 0.126 cm2 and 1.020 cm2, respectively, with negligible current hysteresis and enhanced stability. Besides, perovskite films with a size of 10 × 10 cm2, and an assembled 16 cm2(5 × 5 cm2 module) perovskite solar module with a PCE of over 11% were constructed.

Keywords
Perovskite solar cells, Ethylammonium chloride, Large grains, Additive engineering, Solvent bathing, Perovskite solar module
National Category
Materials Engineering Nano Technology
Research subject
Chemistry; Physics
Identifiers
urn:nbn:se:kth:diva-234552 (URN)10.1016/j.nanoen.2018.08.072 (DOI)000448994600045 ()2-s2.0-85052970311 (Scopus ID)
Note

QC 20180910

Available from: 2018-09-07 Created: 2018-09-07 Last updated: 2018-11-16Bibliographically approved
Hao, Y., Yang, W., Karlsson, K. M., Cong, J., Wang, S., Lo, X., . . . Boschloo, G. (2018). Efficient Dye-Sensitized Solar Cells with Voltages Exceeding 1 V through Exploring Tris(4-alkoxyphenyl)amine Mediators in Combination with the Tris(bipyridine) Cobalt Redox System. ACS ENERGY LETTERS, 3(8), 1929-1937
Open this publication in new window or tab >>Efficient Dye-Sensitized Solar Cells with Voltages Exceeding 1 V through Exploring Tris(4-alkoxyphenyl)amine Mediators in Combination with the Tris(bipyridine) Cobalt Redox System
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2018 (English)In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 3, no 8, p. 1929-1937Article in journal (Refereed) Published
Abstract [en]

Tandem redox electrolytes, prepared by the addition of a tris(p-anisyl)amine mediator into classic tris(bipyridine)cobalt-based electrolytes, demonstrate favorable electron transfer and reduced energy loss in dye-sensitized solar cells. Here, we have successfully explored three tris(4-alkoxyphenyl)-amine mediators with bulky molecular structures and generated more effective tandem redox systems. This series of tandem redox electrolytes rendered solar cells with very high photovoltages exceeding 1 V, which approaches the theoretical voltage limit of tris(bipyridine)cobalt-based electrolytes. Solar cells with power conversion efficiencies of 9.7-11.0% under 1 sun illumination were manufactured. This corresponds to an efficiency improvement of up to 50% as compared to solar cells based on pure tris(bipyridine)cobalt-based electrolytes. The photovoltage increases with increasing steric effects of the tris(4-alkoxyphenyl)amine mediators, which is attributed to a retarded recombination kinetics. These results highlight the importance of structural design for optimized charge transfer at the sensitized semiconductor/electrolyte interface and provide insights for the future development of efficient dye-sensitized solar cells.

National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-234632 (URN)10.1021/acsenergylett.8b00872 (DOI)000441852800021 ()2-s2.0-85050104939 (Scopus ID)
Funder
Swedish Energy AgencySwedish Research CouncilStiftelsen Olle Engkvist ByggmästareStandUp
Note

QC 20180912

Available from: 2018-09-12 Created: 2018-09-12 Last updated: 2018-09-12Bibliographically approved
Sharmoukh, W., Cong, J., Gao, J., Liu, P., Quentin, D. & Kloo, L. (2018). Molecular Engineering of D-D-pi-A-Based Organic Sensitizers for Enhanced Dye-Sensitized Solar Cell Performance. ACS OMEGA, 3(4), 3819-3829
Open this publication in new window or tab >>Molecular Engineering of D-D-pi-A-Based Organic Sensitizers for Enhanced Dye-Sensitized Solar Cell Performance
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2018 (English)In: ACS OMEGA, ISSN 2470-1343, Vol. 3, no 4, p. 3819-3829Article in journal (Refereed) Published
Abstract [en]

A series of molecularly engineered and novel dyes WS1, WS2, WS3, and WS4, based on the D35 donor, 1-(4-hexylphenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole and 4-(4-hexylphenyl)-4H-dithieno[3,2-b: 2', 3'-d] pyrrole as pi-conjugating linkers, were synthesized and compared to the well-known LEG4 dye. The performance of the dyes was investigated in combination with an electrolyte based on Co(II/III) complexes as redox shuttles. The electron recombination between the redox mediators in the electrolyte and the TiO2 interface decreases upon the introduction of 4-hexylybenzene entities on the 2,5-di(thiophen-2-yl)-1H-pyrrole and 4H-dithieno[3,2-b: 2', 3'-d] pyrrole linker units, probably because of steric hindrance. The open circuit photovoltage of WS1-, WS2-, WS3-, and WS4-based devices in combination with the Co(II/III)-based electrolyte are consistently higher than those based on a I-/I-3(-) electrolyte by 105, 147, 167, and 75 mV, respectively. The WS3-based devices show the highest power conversion efficiency of 7.4% at AM 1.5 G 100 mW/cm(2) illumination mainly attributable to the high open-circuit voltage (V-OC).

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-227229 (URN)10.1021/acsomega.8b00271 (DOI)000430200300022 ()2-s2.0-85045042845 (Scopus ID)
Note

QC 20150514

Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2018-05-14Bibliographically approved
Chen, C., Zhang, W., Cong, J., Cheng, M., Zhang, B., Chen, H., . . . Sun, L. (2017). Cu(II) Complexes as p-Type Dopants in Efficient Perovskite Solar Cells. ACS ENERGY LETTERS, 2(2), 497-503
Open this publication in new window or tab >>Cu(II) Complexes as p-Type Dopants in Efficient Perovskite Solar Cells
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2017 (English)In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 2, no 2, p. 497-503Article in journal (Refereed) Published
Abstract [en]

In this work, two Cu(II) complex compounds are designed and synthesized for applications as p-type dopants in solid-state perovskite solar cells (PSCs). Through the characterization of the optical and electrochemical properties, the complex Cu(bpcm)(2) is shown to be eligible for oxidization of the commonly used hole-transport material (HTM) SpiroOMeTAD. The reason is the electron-withdrawing effect of the chloride groups on the ligands. When the complex was applied as p-type dopant in PSCs containing Spiro-OMeTAD as HTM, an efficiency as high as 18.5% was achieved. This is the first time a Cu(II) pyridine complex has been used as p-type dopant in PSCs.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-204091 (URN)10.1021/acsenergylett.6b00691 (DOI)000394080000031 ()2-s2.0-85034060563 (Scopus ID)
Note

qc 20170329

Available from: 2017-03-29 Created: 2017-03-29 Last updated: 2018-10-22Bibliographically approved
Li, J., Yang, X., Yu, Z., Gurzadyan, G. G., Cheng, M., Zhang, F., . . . Sun, L. (2017). Efficient dye-sensitized solar cells with [copper(6,6′-dimethyl-2,2′-bipyridine)2]2+/1+ redox shuttle. RSC Advances, 7(8), 4611-4615
Open this publication in new window or tab >>Efficient dye-sensitized solar cells with [copper(6,6′-dimethyl-2,2′-bipyridine)2]2+/1+ redox shuttle
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2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 8, p. 4611-4615Article in journal (Refereed) Published
Abstract [en]

The [copper(6,6′-dimethyl-2,2′-bipyridine)2]2+/1+ ([Cu(dmbp)2]2+/1+) redox couple, which possesses a distorted tetragonal geometry of a Cu(i) complex crystal and a distorted tetrahedral coordination geometry of Cu(ii) complex crystal, has been developed as a redox mediator in dye-sensitized solar cells (DSSCs). The energy of loss for dye regeneration was reduced with a very low but sufficient driving force of only 0.11 eV. A distinct increase in open-circuit voltage (VOC) was achieved and a remarkable power conversion efficiency of 10.3% was afforded at 100 mW cm−2 under AM 1.5G condition.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
Keywords
Coordination reactions, Copper, Copper compounds, Open circuit voltage, Solar cells, Driving forces, Dye regeneration, Power conversion efficiencies, Redox couple, Redox mediators, Redox shuttle, Tetragonal geometry, Tetrahedral coordination geometry, Dye-sensitized solar cells
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-202260 (URN)10.1039/c6ra25676g (DOI)000393751300045 ()2-s2.0-85010341409 (Scopus ID)
Note

 QC 20170306

Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2017-11-29Bibliographically approved
Hao, Y., Saygili, Y., Cong, J., Eriksson, A., Yang, W., Zhang, J., . . . Boschloo, G. (2016). Novel Blue Organic Dye for Dye-Sensitized Solar Cells Achieving High Efficiency in Cobalt-Based Electrolytes and by Co-Sensitization. ACS Applied Materials and Interfaces, 8(48), 32797-32804
Open this publication in new window or tab >>Novel Blue Organic Dye for Dye-Sensitized Solar Cells Achieving High Efficiency in Cobalt-Based Electrolytes and by Co-Sensitization
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2016 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 48, p. 32797-32804Article in journal (Refereed) Published
Abstract [en]

Blue and green dyes as well as NIR-absorbing dyes have attracted great interest because of their excellent ability of absorbing the incident photons in the red and near-infrared range region. A novel blue D-pi-A dye (Dyenamo Blue), based on the diketopyrrolopyrrole (DPP)-core, has been designed and synthesized. Assembled with the cobalt bipyridine-based electrolytes, the device with Dyenamo Blue achieved a satisfying efficiency of 7.3% under one sun (AM1.5 G). The co-sensitization strategy was further applied on this blue organic dye together with a red D-pi-A dye (D35). The successful co-sensitization outperformed a panchromatic light absorption and improved the photocurrent density; this in addition to the open-circuit potential result in an efficiency of 8.7%. The extended absorption of the sensitization and the slower recombination reaction between the blue dye and TiO2 surface inhibited by the additional red sensitizer could be the two main reasons for the higher performance. In conclusion, from the results, the highly efficient cobalt-based DSSCs could be achieved with the co-sensitization between red and blue D-pi-A organic dyes with a proper design, which showed us the possibility of applying this strategy for future high-performance solar cells.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2016
Keywords
blue color, organic dyes, co-sensitization, cobalt electrolyte, dye-sensitized solar cells
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-199484 (URN)10.1021/acsami.6b09671 (DOI)000389624600020 ()2-s2.0-85002658339 (Scopus ID)
Note

QC 20170120

Available from: 2017-01-20 Created: 2017-01-09 Last updated: 2017-11-29Bibliographically approved
Kloo, L., Gao, J., Bhagavathiachari, M. & Cong, J. (2014). Strategies to improve the performance of one- electron redox systems in electrolytes for dyes-sensitized solar cells. Paper presented at 247th National Spring Meeting of the American-Chemical-Society (ACS), MAR 16-20, 2014, Dallas, TX. Abstract of Papers of the American Chemical Society, 247, 85-ENFL
Open this publication in new window or tab >>Strategies to improve the performance of one- electron redox systems in electrolytes for dyes-sensitized solar cells
2014 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247, p. 85-ENFL-Article in journal, Meeting abstract (Other academic) Published
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-160783 (URN)000348455205090 ()
Conference
247th National Spring Meeting of the American-Chemical-Society (ACS), MAR 16-20, 2014, Dallas, TX
Note

QC 20150302

Available from: 2015-03-02 Created: 2015-02-27 Last updated: 2017-12-04Bibliographically approved
Hao, Y., Tian, H., Cong, J., Yang, W., Bora, I., Sun, L., . . . Hagfeldt, A. (2014). Triphenylamine Groups Improve Blocking Behavior of Phenoxazine Dyes in Cobalt-Electrolyte-Based Dye-Sensitized Solar Cells. ChemPhysChem, 15(16), 3476-3483
Open this publication in new window or tab >>Triphenylamine Groups Improve Blocking Behavior of Phenoxazine Dyes in Cobalt-Electrolyte-Based Dye-Sensitized Solar Cells
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2014 (English)In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 15, no 16, p. 3476-3483Article in journal (Refereed) Published
Abstract [en]

Novel phenoxazine dyes are successfully introduced as sensitizers into dye-sensitized solar cells (DSCs) with cobalt-based electrolyte. In sensitizers with triphenylamine (TPA) groups recombination from electrons in the TiO2 conduction band to the cobalt(III) species is suppressed. The effect of the steric properties of the phenoxazine sensitizers on the overall device performance and on recombination and regeneration processes is compared. Optimized DSCs sensitized with IB2 having two TPA groups in combination with tris(2,2'-bipyridyl) cobalt( II/III) yield efficiencies of 6.3 %, similar to that of IB3, which is equipped with mutiple alkoxy groups. TH310 with only one TPA group gives lower efficiency and open circuit voltage, while IB1 without TPA groups performs even worse. These results demonstrate that both TPA groups on the IB2 are needed for an efficient blocking effect. These results reveal a possible new role for TPA units in DSC sensitizer design.

Keywords
blocking effect, cobalt redox mediator, dye-sensitized solar cells, phenoxazine dyes, triphenylamine
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-157024 (URN)10.1002/cphc.201402474 (DOI)000344370900009 ()25123399 (PubMedID)
Funder
Swedish Energy AgencySwedish Research CouncilStandUpKnut and Alice Wallenberg Foundation
Note

QC 20141205

Available from: 2014-12-05 Created: 2014-12-04 Last updated: 2017-12-05Bibliographically approved
Cong, J., Hao, Y., Sun, L. & Kloo, L. (2014). Two Redox Couples are Better Than One: Improved Current and Fill Factor from Cobalt-Based Electrolytes in Dye-Sensitized Solar Cells. Advanced Energy Materials, 4(8), 1301273
Open this publication in new window or tab >>Two Redox Couples are Better Than One: Improved Current and Fill Factor from Cobalt-Based Electrolytes in Dye-Sensitized Solar Cells
2014 (English)In: Advanced Energy Materials, ISSN 1614-6832, Vol. 4, no 8, p. 1301273-Article in journal (Refereed) Published
Abstract [en]

A tandem redox strategy is used in cobalt-based electrolytes. Co(bpy) 3 2+/Co(bpy)3 3+ offers a high photovoltage at the photoanode, whereas the I-/I3 - or Fc/Fc+ redox couples facilitate charge transfer at the counter electrode. Electron exchange in the electrolyte offers beneficial concentration gradients. The overall conversion efficiency is improved from 6.5% to 7.5%.

Keywords
electrolytes, photoelectrochemistry, redox chemistry, solar cells, tandem redox systems
National Category
Chemical Sciences Energy Engineering
Identifiers
urn:nbn:se:kth:diva-148317 (URN)10.1002/aenm.201301273 (DOI)000338020900001 ()2-s2.0-84902084202 (Scopus ID)
Funder
Swedish Research CouncilSwedish Energy AgencyKnut and Alice Wallenberg Foundation
Note

QC 20140806

Available from: 2014-08-06 Created: 2014-08-05 Last updated: 2014-08-06Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-8084-1181

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