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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
Vasileva, E., Baitenov, A., Chen, H., Li, Y., Sychugov, I., Yan, M., . . . Popov, S. (2019). Effect of transparent wood on the polarization degree of light. Optics Letters, 44(12), 2962-2965
Open this publication in new window or tab >>Effect of transparent wood on the polarization degree of light
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2019 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 44, no 12, p. 2962-2965Article in journal (Refereed) Published
Abstract [en]

We report on the study of polarization properties of light propagating through transparent wood (TW), which is an anisotropically scattering medium, and consider two cases: completely polarized and totally unpolarized light. It was demonstrated that scattered light distribution is affected by the polarization state of incident light. Scattering is the most efficient for light polarized parallel to cellulose fibers. Furthermore, unpolarized light becomes partially polarized (with a polarization degree of 50%) after propagating through the TW. In the case of totally polarized incident light, however, the degree of polarization of transmitted light is decreased, in an extreme case to a few percent, and reveals an unusual angular dependence on the material orientation. The internal hierarchical complex structure of the material, in particular cellulose fibrils organized in lamellae, is believed to be responsible for the change of the light polarization degree. It was demonstrated that the depolarization properties are determined by the angle between the polarization of light and the wood fibers, emphasizing the impact of their internal structure, unique for different wood species.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-255191 (URN)10.1364/OL.44.002962 (DOI)000471636700005 ()31199356 (PubMedID)2-s2.0-85067943575 (Scopus ID)
Note

QC 20190904

Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2019-09-04Bibliographically approved
Wang, L., Sheibani, E., Guo, Y., Zhang, W., Li, Y., Liu, P., . . . Sun, L. (2019). Impact of Linking Topology on the Properties of Carbazole-Based Hole-Transport Materials and their Application in Solid-State Mesoscopic Solar Cells. SOLAR RRL, Article ID 1900196.
Open this publication in new window or tab >>Impact of Linking Topology on the Properties of Carbazole-Based Hole-Transport Materials and their Application in Solid-State Mesoscopic Solar Cells
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2019 (English)In: SOLAR RRL, ISSN 2367-198X, article id 1900196Article in journal (Refereed) Epub ahead of print
Abstract [en]

Carbazole is a promising core for the molecular design of hole-transport materials (HTMs) for solid-state mesoscopic solar cells (ssMSCs), such as solid-state dye-sensitized solar cells (ssDSSCs) and perovskite solar cells (PSCs) due to its low cost and excellent optoelectronic properties of its derivatives. Although carbazole-based HTMs are intensely investigated in ssMSCs and promising device performance is demonstrated, the fundamental understanding of the impact of linking topology on the properties of carbazole-based HTMs is lacking. Herein, the effect of the linking topology on the optical and electronic properties of a series of carbazole-based HTMs with 2,7-substitution and 3,6-substitution is systematically investigated. The results demonstrate that the 2,7-substituted carbazole-based HTMs display higher hole mobility and conductivity among this series of analogous molecules, thereby exhibiting better device performance. In addition, the conductivity of the HTMs is improved after light treatment, which explains the commonly observed light-soaking phenomenon of ssMSCs in general. All these carbazole-based HTMs are successfully applied in ssMSCs and one of the HTMs X50-based devices yield a promising efficiency of 6.8% and 19.2% in ssDSSCs and PSCs, respectively. This study provides guidance for the molecular design of effective carbazole-based HTMs for high-performance ssMSCs and related electronic devices.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2019
Keywords
hole-transport materials, carbazole, linking topology, mesoscopic solar cells, perovskite solar cells
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-255742 (URN)10.1002/solr.201900196 (DOI)000477425300001 ()
Note

QC 20190813

Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-13Bibliographically approved
Zhang, W., Sadollahkhani, A., Li, Y., Leandri, V., Gardner, J. M. & Kloo, L. (2019). Mechanistic Insights from Functional Group Exchange Surface Passivation: A Combined Theoretical and Experimental Study. ACS APPLIED ENERGY MATERIALS, 2(4), 2723-2733
Open this publication in new window or tab >>Mechanistic Insights from Functional Group Exchange Surface Passivation: A Combined Theoretical and Experimental Study
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2019 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 4, p. 2723-2733Article in journal (Refereed) Published
Abstract [en]

Four different functional groups including amino (-NH2), phosphine (-PH2), hydroxyl (-OH), and thiol (-SH) were combined with POSS (polyhedral oligomeric silsesquioxane) molecules to investigate how functional groups affect the surface passivation of POSS systems. Results from density-functional theory (DFT) calculations indicate that functional group amino (-NH2) with adsorption energy 86 (56) kJ mol(-1) is consistently better than that of thiol (-SH) with adsorption energy 68 (43) kJ mor(-1) for different passivation mechanisms. Theoretical studies on the analogous POSS-OH and POSS-PH2 systems show similar adsorption energies. Two of the systems were also investigated experimentally; aminopropyl isobutyl POSS (POSS-NH2) and mercaptopropyl isobutyl POSS (POSS-SH) were applied as passivation materials for MAPbI(3) (MA = methylammonium) perovskite and (FA)(0.85)(MA)(0.15)Pb(I-3)(0.85)(Br-3)(0)(.15)(FA = formamidinium) perovskite films. The same conclusion was drawn based on the results from contact angle studies, X-ray diffraction (XRD), and the stability of solar cells in ambient atmosphere, indicating the vital importance of choice of functional groups for passivation of the perovskite materials.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
perovskite solar cells, polyhedral oligomeric silsesquioxane (POSS), passivation, DFT calculation, stability
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-251284 (URN)10.1021/acsaem.9b00050 (DOI)000465644600047 ()
Note

QC 20190517

Available from: 2019-05-17 Created: 2019-05-17 Last updated: 2019-05-17Bibliographically approved
Montanari, C., Li, Y. & Berglund, L. (2019). Multifunctional transparent wood for thermal energy storage applications. Paper presented at National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL. Abstracts of Papers of the American Chemical Society, 257
Open this publication in new window or tab >>Multifunctional transparent wood for thermal energy storage applications
2019 (English)In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-257608 (URN)000478860503020 ()
Conference
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Note

QC 20190918

Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2019-09-18Bibliographically approved
Li, Y., Cheng, M., Jungstedt, E., Xu, B., Sun, L. & Berglund, L. (2019). Optically Transparent Wood Substrate for Perovskite Solar Cells. ACS Sustainable Chemistry and Engineering, 7(6), 6061-6067
Open this publication in new window or tab >>Optically Transparent Wood Substrate for Perovskite Solar Cells
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2019 (English)In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, no 6, p. 6061-6067Article in journal (Refereed) Published
Abstract [en]

Transparent wood is a candidate for use as an energy-saving building material due to its low density (ca. 1.2 g/cm(3)), high optical transmittance (over 85% at 1 mm thickness), low thermal conductivity (0.23 W m(-1) K-1), and good load-bearing performance with tough failure behavior (no shattering). High optical transmittance also makes transparent wood a candidate for optoelectronic devices. In this work, for the first time, perovskite solar cells processed at low temperature (<150 degrees C) were successfully assembled directly on transparent wood substrates. A power conversion efficiency up to 16.8% was obtained. The technologies demonstrated may pave the way for integration of solar cells with light transmitting wood building structures for energy-saving purposes.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
Biocomposite, Perovskite solar cell, Energy-Efficient, Building material, Transparent wood, Mechanical properties
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-248333 (URN)10.1021/acssuschemeng.8b06248 (DOI)000461978200051 ()30918764 (PubMedID)2-s2.0-85063061391 (Scopus ID)
Note

QC 20190410

Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-04-10Bibliographically approved
Zhang, W., Hua, Y., Wang, L., Zhang, B., Li, Y., Liu, P., . . . Kloo, L. (2019). The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells. ACS APPLIED ENERGY MATERIALS, 2(9), 6768-6779
Open this publication in new window or tab >>The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells
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2019 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 9, p. 6768-6779Article in journal (Refereed) Published
Abstract [en]

Two zinc-based coordination complexes Y3 and Y4 have been synthesized and characterized, and their performance as hole-transport materials (HTMs) for perovskite solar cells (PSCs) has been investigated. The complex Y3 contains two separate ligands, and the molecular structure can be seen as a disconnected porphyrin ring. On the other hand, Y4 consists of a porphyrin core and therefore is a more extended conjugated system as compared to Y3. The optical and redox properties of the two different molecular complexes are comparable. However, the hole mobility and conductivity of Y4 as macroscopic material are remarkably higher than that of Y3. Furthermore, when employed as hole-transport materials in perovskite solar cells, cells containing Y4 show a power conversion efficiency (PCE) of 16.05%, comparable to the Spiro-OMeTAD-based solar cells with an efficiency around 17.08%. In contrast, solar cells based on Y3 show a negligible efficiency of about 0.01%. The difference in performance of Y3 and Y4 is analyzed and can be attributed to the difference in packing of the nonplanar and planar building blocks in the corresponding materials.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
ligand conjugation, coordination complex, porphyrin, hole-transport material, perovskite
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-261967 (URN)10.1021/acsaem.9b01223 (DOI)000487770000073 ()
Note

QC 20191014

Available from: 2019-10-14 Created: 2019-10-14 Last updated: 2019-10-14Bibliographically approved
Chen, H., Baitenov, A., Li, Y., Vasileva, E., Popov, S., Sychugov, I., . . . Berglund, L. (2019). Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects. ACS Applied Materials and Interfaces, 11(38), 35451-35457
Open this publication in new window or tab >>Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 38, p. 35451-35457Article in journal (Refereed) Published
Abstract [en]

Transparent wood (TW) is an emerging optical material combining high optical transmittance and haze for structural applications. Unlike nonscattering absorbing media, the thickness dependence of light transmittance for TW is complicated because optical losses are also related to increased photon path length from multiple scattering. In the present study, starting from photon diffusion equation, it is found that the angle-integrated total light transmittance of TW has an exponentially decaying dependence on sample thickness. The expression reveals an attenuation coefficient which depends not only on the absorption coefficient but also on the diffusion coefficient. The total transmittance and thickness were measured for a range of TW samples, from both acetylated and nonacetylated balsa wood templates, and were fitted according to the derived relationship. The fitting gives a lower attenuation coefficient for the acetylated TW compared to the nonacetylated one. The lower attenuation coefficient for the acetylated TW is attributed to its lower scattering coefficient or correspondingly lower haze. The attenuation constant resulted from our model hence can serve as a singular material parameter that facilitates cross-comparison of different sample types, at even different thicknesses, when total optical transmittance is concerned. The model was verified with two other TWs (ash and birch) and is in general applicable to other scattering media.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
transparent wood, transmittance, photon diffusion equation, attenuation coefficient, anisotropic scattering
National Category
Physical Sciences
Research subject
Physics, Material and Nano Physics; Physics, Material and Nano Physics
Identifiers
urn:nbn:se:kth:diva-262791 (URN)10.1021/acsami.9b11816 (DOI)000488322900100 ()31483595 (PubMedID)2-s2.0-85072687041 (Scopus ID)
Note

QC 20191022

Available from: 2019-10-22 Created: 2019-10-22 Last updated: 2019-11-20Bibliographically approved
Koivurova, M., Vasileva, E., Li, Y., Berglund, L. & Popov, S. (2018). Complete spatial coherence characterization of quasi-random laser emission from dye doped transparent wood. Optics Express, 26(10), 13474-13482
Open this publication in new window or tab >>Complete spatial coherence characterization of quasi-random laser emission from dye doped transparent wood
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2018 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, no 10, p. 13474-13482Article in journal (Refereed) Published
Abstract [en]

We report on the experimental determination of the complete two coordinate spatial coherence function of light emitted by a quasi-random laser, implemented on recently introduced dye-doped transparent wood. The spatial coherence was measured by means of a double grating interferometer, which has some advantages over the standard Young's interferometer. Analysis of the spatial coherence reveals that emission from such a material can be considered as a superposition of several spatial modes produced by individual emitters within semi-ordered scattering medium. The overall degree of coherence, (gamma)over-bar, for this quasi-random laser was found to be 0.16 +/- 0.01, having possible applications in speckle free laser imaging and illumination.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2018
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-231223 (URN)10.1364/OE.26.013474 (DOI)000432457600117 ()29801372 (PubMedID)2-s2.0-85047074022 (Scopus ID)
Note

QC 20180628

Available from: 2018-06-28 Created: 2018-06-28 Last updated: 2018-11-26Bibliographically approved
Hua, Y., Liu, P., Li, Y., Sun, L. & Kloo, L. (2018). Composite Hole-Transport Materials Based on a Metal-Organic Copper Complex and Spiro-OMeTAD for Efficient Perovskite Solar Cells. SOLAR RRL, 2(5), Article ID UNSP 1700073.
Open this publication in new window or tab >>Composite Hole-Transport Materials Based on a Metal-Organic Copper Complex and Spiro-OMeTAD for Efficient Perovskite Solar Cells
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2018 (English)In: SOLAR RRL, ISSN 2367-198X, Vol. 2, no 5, article id UNSP 1700073Article in journal (Refereed) Published
Abstract [en]

Spiro-OMeTAD has been the most commonly used hole-transport material in perovskite solar cells. However, this material shows intrinisic drawbacks, such as low hole mobility and conductivity in its pristine form, as well as self-aggregation when deposited as thin film. These are not beneficial properties for efficient hole transport and extraction. In order to address these issues, we have designed a new type of composite hole-transport materials based on a new metal-organic copper complex (CuH) and Spiro-OMeTAD. The incorporation of the molecularly bulky HTM CuH into the Spiro-OMeTAD material efficiently improves the hole mobility and suppresses the aggregation in the Spiro-OMeTAD film. As a result, the conversion efficiencies obtained for perovskite solar cells based on the composite HTM system reached as high as 18.83%, which is superior to solar cells based on the individual hole-transport materials CuH (15.75%) or Spiro-OMeTAD (14.47%) under the same working conditions. These results show that composite HTM systems may constitute an effective strategy to further improve the efficiency of perovskite solar cells.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
Hole transport materials, mobility, perovskite solar cells, small molecules
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-228439 (URN)10.1002/solr.201700073 (DOI)000432036200001 ()
Note

QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-05-29Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1591-5815

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