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Publications (10 of 476) Show all publications
Zhang, L., Yang, X., Wang, W., Gurzadyan, G. G., Li, J., Li, X., . . . Sun, L. (2019). 13.6% Efficient Organic Dye-Sensitized Solar Cells by Minimizing Energy Losses of the Excited State. ACS ENERGY LETTERS, 4(4), 943-951
Open this publication in new window or tab >>13.6% Efficient Organic Dye-Sensitized Solar Cells by Minimizing Energy Losses of the Excited State
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2019 (English)In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 4, no 4, p. 943-951Article in journal (Refereed) Published
Abstract [en]

The electron-injection energy losses of dye-sensitized solar cells (DSSCs) are among the fundamental problems hindering their successful breakthrough application. Two triazatruxene (TAT)-based sensitizers, with one containing a flexible Z-type double bond and another a rigid single bond, coded as ZL001 and ZL003, respectively, have been synthesized and applied in DSSCs to probe the energy losses in the process of electron injection. Using time-resolved laser spectroscopic techniques in the kinetic study, ZL003 with the rigid single bond promotes much faster electron injection into the conductive band of TiO2 especially in the locally excited state (hot injection), which leads to higher electron density in TiO2 and a higher V-oc. The devices based on ZL003 exhibited a champion power conversion efficiency (PCE) of 13.6% with V-oc = 956 mV, J(sc) = 20.73 mA cm(-2), and FF = 68.5%, which are among the highest recorded results to date on single dye-sensitized DSSCs. An independent certified PCE of 12.4% has been obtained for devices based on ZL003.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-251335 (URN)10.1021/acsenergylett.9b00141 (DOI)000464889300021 ()2-s2.0-85064383453 (Scopus ID)
Note

QC 20190523

Available from: 2019-05-23 Created: 2019-05-23 Last updated: 2019-05-23Bibliographically approved
Zhang, B. & Sun, L. (2019). Across the Board: Licheng Sun on the Mechanism of O-O Bond Formation in Photosystem II. ChemSusChem, 12(14), 3401-3404
Open this publication in new window or tab >>Across the Board: Licheng Sun on the Mechanism of O-O Bond Formation in Photosystem II
2019 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 12, no 14, p. 3401-3404Article in journal (Refereed) Published
Abstract [en]

In this series of articles, the board members of ChemSusChem discuss recent research articles that they consider of exceptional quality and importance for sustainability. This entry features Prof. L. Sun, who proposes a special mechanism for O-O bond formation in photosystem II with involvement of an Mn-VII-oxo species induced by charge- and structural rearrangements. In this viewpoint, Proton transfer is involved in changes of the first coordination spheres around the Mn-VII-oxo site on the dangling Mn4 with de- and re-coordination of carboxylates (Glu333 and Asp170).

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
disproportionation, oxygen evolution, photosystem II, structural rearrangement, water splitting
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:kth:diva-257575 (URN)10.1002/cssc.201901438 (DOI)000478633900023 ()31240851 (PubMedID)2-s2.0-85068351514 (Scopus ID)
Note

QC 20190923

Available from: 2019-09-23 Created: 2019-09-23 Last updated: 2019-09-23Bibliographically approved
Zhang, B. & Sun, L. (2019). Artificial photosynthesis: opportunities and challenges of molecular catalysts. Chemical Society Reviews, 48(7), 2216-2264
Open this publication in new window or tab >>Artificial photosynthesis: opportunities and challenges of molecular catalysts
2019 (English)In: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 48, no 7, p. 2216-2264Article, review/survey (Refereed) Published
Abstract [en]

Molecular catalysis plays an essential role in both natural and artificial photosynthesis (AP). However, the field of molecular catalysis for AP has gradually declined in recent years because of doubt about the long-term stability of molecular-catalyst-based devices. This review summarizes the development history of molecular-catalyst-based AP, including the fundamentals of AP, molecular catalysts for water oxidation, proton reduction and CO2 reduction, and molecular-catalyst-based AP devices, and it provides an analysis of the advantages, challenges, and stability of molecular catalysts. With this review, we aim to highlight the following points: (i) an investigation on molecular catalysis is one of the most promising ways to obtain atom-efficient catalysts with outstanding intrinsic activities; (ii) effective heterogenization of molecular catalysts is currently the primary challenge for the application of molecular catalysis in AP devices; (iii) development of molecular catalysts is a promising way to solve the problems of catalysis involved in practical solar fuel production. In molecular-catalysis-based AP, much has been attained, but more challenges remain with regard to long-term stability and heterogenization techniques.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-251498 (URN)10.1039/c8cs00897c (DOI)000464383500009 ()30895997 (PubMedID)2-s2.0-85063728666 (Scopus ID)
Note

QC 20190516

Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-05-16Bibliographically approved
Guo, Y., Yao, Z., Timmer, B. J. J., Sheng, X., Fan, L., Li, Y., . . . Sun, L. (2019). Boosting nitrogen reduction reaction by bio-inspired FeMoS containing hybrid electrocatalyst over a wide pH range. Nano Energy, 62, 282-288
Open this publication in new window or tab >>Boosting nitrogen reduction reaction by bio-inspired FeMoS containing hybrid electrocatalyst over a wide pH range
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2019 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 62, p. 282-288Article in journal (Refereed) Published
Abstract [en]

A facile preparation of bio-inspired and morphology controllable catalytic electrode FeS@MoS2/CFC, featuring a carbon fiber cloth (CFC) covered with FeS dotted MoS2 nanosheets, has been established. Synergy between the CFC as a self-standing conductive substrate and the FeS nanoparticle dotted MoS2 nanosheets with abundant active sites makes the noble-metal-free catalytic electrode FeS@MoS2/CFC highly efficient in nitrogen reduction reaction (NRR), with an ammonia production rate of 8.45 mu g h(-1) cm(-2) and excellent long-term stability at -0.5 V in pH neutral electrolyte. Further electrolysis in acidic and alkaline electrolytes revealed the overall NRR catalytic activity of this electrode over a wide pH range.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
FeS nanoparticles, MoS2 nanosheets, Nitrogen reduction reaction, Bioinspired catalysts
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-255360 (URN)10.1016/j.nanoen.2019.05.051 (DOI)000474636100033 ()2-s2.0-85065865579 (Scopus ID)
Note

QC 20190731

Available from: 2019-07-31 Created: 2019-07-31 Last updated: 2019-07-31Bibliographically approved
Cai, B., Yang, X., Jiang, X., Yu, Z., Hagfeldt, A. & Sun, L. (2019). 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. Journal of Materials Chemistry A, 7(24), 14835-14841
Open this publication in new window or tab >>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
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2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 24, p. 14835-14841Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-255482 (URN)10.1039/c9ta04166d (DOI)000474712700044 ()2-s2.0-85067577476 (Scopus ID)
Note

QC 20190919

Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-09-19Bibliographically approved
Zhang, J., Hao, Y., Yang, L., Mohammadi, H., Vlachopoulos, N., Sun, L., . . . Sheibani, E. (2019). Electrochemically polymerized poly (3, 4-phenylenedioxythiophene) as efficient and transparent counter electrode for dye sensitized solar cells. Electrochimica Acta, 300, 482-488
Open this publication in new window or tab >>Electrochemically polymerized poly (3, 4-phenylenedioxythiophene) as efficient and transparent counter electrode for dye sensitized solar cells
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2019 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 300, p. 482-488Article in journal (Refereed) Published
Abstract [en]

A new conducting polymer poly (3, 4-phenylenedioxythiophene) is synthesized by the electrochemical polymerization technique with different solvents. We find that solvents used in electrochemical polymerization play important roles for the catalytic activity and morphology of the formed conducting polymers. The obtained poly (3, 4-phenylenedioxythiophene) is for the first time employed as counter electrode electrocatalyst in dye sensitized solar cells with cobalt-based electrolytes. We demonstrate that a polymer prepared from a mixed acetonitrile-dichloromethane solvent exhibit higher catalytic activity for redox reactions, as compared to that from a single solvent, dichloromethane. The devices based on this mixed solvent-based polymer from a mixed solvents show a high power conversion efficiency of 5.97%. An additional advantageous feature of the electrochemically polymerized poly (3, 4-phenylenedioxythiophene) for solar cell applications is the high transparency in the visible and nearinfrared region. We also investigate the beneficial effect of the poly (3, 4-phenylenedioxythiophene) layer thickness on device performance, and concluded that the series resistance and charge transfer resistance are greatly influenced by the thickness of polymer, as evidenced by electrochemical impedance spectroscopy measurements. The optimal thickness for poly (3, 4-phenylenedioxythiophene) is about 100 nm. Furthermore, the high catalytic activity and transparency of the new conducting polymer as counter electrode shows great promise for other optoelectronic applications.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
poly(PheDOT), Counter electrode, Dye sensitized solar cells, Electrochemical polymerization
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-245127 (URN)10.1016/j.electacta.2019.01.006 (DOI)000458488200057 ()2-s2.0-85061301933 (Scopus ID)
Note

QC 20190315

Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-06-11Bibliographically approved
Elawad, M., Sun, L., Mola, G. T., Yu, Z. & Arbab, E. A. (2019). Enhanced performance of perovskite solar cells using p-type doped PFB:F4TCNQ composite as hole transport layer. Journal of Alloys and Compounds, 771, 25-32
Open this publication in new window or tab >>Enhanced performance of perovskite solar cells using p-type doped PFB:F4TCNQ composite as hole transport layer
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2019 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 771, p. 25-32Article in journal (Refereed) Published
Abstract [en]

Conjugated polymers have been widely used as hole transport materials (HTM) in the preparation of mesoscopic perovskite solar cells (PSCs). In this work, we employed p-type doped conducting polymer known as poly(9,9-dioctylfluorene-co-bis-N,N-(-4-butyl phenyl)-bis-N,N-phenyl-1,4-phenylenediamine) (PFB) as a hole transport material (HTM) in perovskite based solar cell. The effect of dopant concentration on the optical and electrical properties of PEB was investigated to optimize the electrical properties of the material for the best function of the solar cell. The highest power conversion efficiency of mesoscopic perovskite solar cells (PSCs), fabricated in this investigation, was found to be 14.04% which is 57% higher than that of pristine PFB hole transport layer. The UV–Vis absorption and Raman spectroscopy measurements confirm the occurrence of oxidation in a p-type doped PFB hole transport layer. This is attributed to the transfer of electrons from the highest occupied molecular orbital (HOMO) of PEB to the lowest unoccupied molecular orbital (LUMO) of F4TCNQ. The solar cells produced using p-type doped PFB:F4TCNQ composite not only improves device performances but also shows superior long-term stability. The optical, morphological and electrical properties of the doped composite PFB: F4TCNQ and newly fabricated devices are presented and discussed in this paper.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Device stability, Hole transport material, P-type PFB, Perovskite, Solar cell, Conducting polymers, Conjugated polymers, Doping (additives), Hole mobility, Molecular orbitals, Perovskite solar cells, Photoconducting materials, Polymer solar cells, Superconducting materials, Highest occupied molecular orbital, Hole transport materials, Lowest unoccupied molecular orbital, N-phenyl-1, 4-phenylenediamine, Optical and electrical properties, P-type, Raman spectroscopy measurements, Solar cells
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-236331 (URN)10.1016/j.jallcom.2018.08.025 (DOI)000449621500004 ()2-s2.0-85052655348 (Scopus ID)
Funder
Swedish Energy AgencyKnut and Alice Wallenberg Foundation
Note

QC 20181109

Available from: 2018-11-09 Created: 2018-11-09 Last updated: 2018-11-28Bibliographically approved
Leandri, V., Pizzichetti, A. R., Xu, B., Franchi, D., Zhang, W., Benesperi, I., . . . Gardner, J. M. (2019). Exploring the Optical and Electrochemical Properties of Homoleptic versus Heteroleptic Diimine Copper(I) Complexes. Inorganic Chemistry, 58(18), 12167-12177
Open this publication in new window or tab >>Exploring the Optical and Electrochemical Properties of Homoleptic versus Heteroleptic Diimine Copper(I) Complexes
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2019 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 18, p. 12167-12177Article in journal (Refereed) Published
Abstract [en]

Due to ligand scrambling, the synthesis and investigation of the properties of heteroleptic Cu(I) complexes can be a challenging task. In this work, we have studied the optical and electrochemical properties of a series of homoleptic complexes, such as [Cu(dbda)(2)](+), [Cu(dmp)(2)](+), [Cu(Br-dmp)(2)](+), [Cu(bcp)(2)](+), [Cu(dsbtmp)(2)](+), [Cu(biq)(2)](+), and [Cu(dap)(2)](+) in solution, and those of their heteroleptics [Cu(dbda)(dmp)](+), [Cu(dbda)(Br-dmp)](+), [Cu(dbda)(bcp)](+), [Cu(dbda)(dsbtmp))(+), [Cu(dbda)(biq)](+), [Cu(dbda)(dap)](+) adsorbed on the surface of anatase TiO2 (dbda = 6,6'-dimethyl-2,2'-bipyridine-4,4'-dibenzoic acid; dmp = 2,9-dimethyl-1,10-phenanthroline; Br-dmp = 5-bromo 2,9-dimethyl-1,10-phenanthroline; bcp = bathocuproine or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; dsbtmp = 2,9-di(sec-butyl)-3,4,7,8-tetramethyl-1,10-phenanthroline; biq = 2,2'-biquinoline; dap = 2,9-dianisyl-1,10-phenanthroline). We show that the maximum absorption wavelengths of the heteroleptic complexes on TiO2 can be reasonably predicted from those of the homoleptic complexes in solution through a simple linear relation, whereas the prediction of their redox properties is less trivial. In the latter case, two different linear patterns emerge: one including the ligands bcp, biq, and dap and another one including the ligands dmp, Br-dmp, and dsbtmp. We offer an interpretation of the data based on the chemical structure of the ligands. On one hand, ligands bcp, biq, and dap possess a more extended pi-conjugated system, which gives a more prominent contribution to the overall redox properties of the ligand dbda. On the other hand, the ligands dmp, Br-dmp, and dsbtmp are all phenanthroline-based containing alkyl substituents and contribute less than dbda to the overall redox properties.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-261306 (URN)10.1021/acs.inorgchem.9b01487 (DOI)000486565600035 ()31483631 (PubMedID)2-s2.0-85072235085 (Scopus ID)
Note

QC 20191008

Available from: 2019-10-08 Created: 2019-10-08 Last updated: 2019-10-08Bibliographically approved
Zhao, Y., Shen, J., Yu, Z., Hu, M., Liu, C., Fan, J., . . . Sun, L. (2019). Fine-tuning the coordination atoms of copper redox mediators: an effective strategy for boosting the photovoltage of dye-sensitized solar cells. Journal of Materials Chemistry A, 7(20), 12808-12814
Open this publication in new window or tab >>Fine-tuning the coordination atoms of copper redox mediators: an effective strategy for boosting the photovoltage of dye-sensitized solar cells
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2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 20, p. 12808-12814Article in journal (Refereed) Published
Abstract [en]

Natural systems have marvelously utilized copper complexes featuring sulfur-coordinating ligands, known as blue copper proteins, as efficient electron-transfer mediators in biological processes. Copper complexes with sulfur-coordinating ligands have been attempted as redox mediators in dye-sensitized solar cells (DSCs), the performance of which is not yet satisfactory and still remains less well explored. Herein, we report the application of new copper complexes bearing a tetradentate polythioether ligand, [(S-4)Cu](2+/+) (1(2+/+), S-4 = 1,4,8,11-tetrathiocyclotetradecane), as a redox mediator in DSCs in comparison with its N-4-tetradentate counterpart [(N-4)Cu](2+/+) (2(2+/+), N-4 = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). Impressively, the changes of coordination atoms from N to S positively shift the formal redox potential of the copper complexes by 600 mV, leading to a remarkably high photovoltage approaching 1.0 V. This is one of the highest photovoltage values reported thus far for DSCs based on copper redox mediators.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-255332 (URN)10.1039/c9ta02735a (DOI)000472219400043 ()2-s2.0-85065996569 (Scopus ID)
Note

QC 20190807

Available from: 2019-08-07 Created: 2019-08-07 Last updated: 2019-08-07Bibliographically approved
Lee, H., Wu, X., Ye, Q., Wu, X., Wang, X., Zhao, Y. & Sun, L. (2019). Hierarchical CoS2/Ni3S2/CoNiOx nanorods with favorable stability at 1 A cm(-2) for electrocatalytic water oxidation. Chemical Communications, 55(11), 1564-1567
Open this publication in new window or tab >>Hierarchical CoS2/Ni3S2/CoNiOx nanorods with favorable stability at 1 A cm(-2) for electrocatalytic water oxidation
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2019 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, no 11, p. 1564-1567Article in journal (Refereed) Published
Abstract [en]

Herein, we have reported an easily synthesized CoS2/Ni3S2/CoNiOx water oxidation catalyst with excellent catalytic activity and superior durability. The as-prepared catalyst required overpotential (eta) as low as 256 mV to exhibit a current density of 10 mA cm(-2) in 1.0 M KOH. Remarkably, it sustained a current density of 1 A cm(-2) for one week in 30% KOH solution with only 25 mV increment of eta. Thus, it is a hopeful candidate as a highly-effective water oxidation electrode in practical applications.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-244518 (URN)10.1039/c8cc09104h (DOI)000457645500003 ()30648178 (PubMedID)2-s2.0-85060927802 (Scopus ID)
Note

QC 20190402

Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-04-02Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-4521-2870

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