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Publications (10 of 447) Show all publications
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
Chen, H., Gao, Y., Ye, L., Yao, Y., Chen, X., Wei, Y. & Sun, L. (2018). A Cu2Se-Cu2O film electrodeposited on titanium foil as a highly active and stable electrocatalyst for the oxygen evolution reaction. Chemical Communications, 54(39), 4979-4982
Open this publication in new window or tab >>A Cu2Se-Cu2O film electrodeposited on titanium foil as a highly active and stable electrocatalyst for the oxygen evolution reaction
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2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 39, p. 4979-4982Article in journal (Refereed) Published
Abstract [en]

Many nonprecious metal-selenide-based materials have been reported as electrocatalysts with high activity for the oxygen evolution reaction (OER). Herein, a hybrid catalyst film composed of Cu2Se and Cu2O nanoparticles directly grown on Ti foil (Cu2Se-Cu2O/TF) was prepared through a simple and fast cathodic electrodeposition method. Surprisingly, this electrode required a relatively low overpotential of 465 mV to achieve a catalytic current density of 10 mA cm-2 for the OER in 0.2 M carbonate buffer (pH = 11.0). Furthermore, a long-term constant current electrolysis test confirmed the high durability of the Cu2Se-Cu2O/TF anode at a current density of 10 mA cm-2 over 20 h. The XRD, TEM and XPS analysis of the sample after the OER indicated that a CuO protective layer formed on the surface of the Cu2Se-Cu2O catalyst, which effectively suppressed further oxidation of the Cu2Se-Cu2O catalyst during the OER and resulted in sustained catalytic oxidation of water.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
Keywords
buffer, carbonic acid, copper oxide, copper selenide, organoselenium derivative, oxygen, titanium, unclassified drug, water, Article, catalyst, chemical reaction, electrolysis, oxidation, pH, surface property, transmission electron microscopy, X ray diffraction, X ray photoemission spectroscopy
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-236423 (URN)10.1039/c8cc02021c (DOI)000435872900019 ()2-s2.0-85046835064 (Scopus ID)
Funder
Swedish Energy AgencySwedish Research Council
Note

QC 20181026

Available from: 2018-10-26 Created: 2018-10-26 Last updated: 2018-10-26Bibliographically approved
Ye, L., Gao, Y., Cao, S., Chen, H., Yao, Y., Hou, J. & Sun, L. (2018). Assembly of highly efficient photocatalytic CO2 conversion systems with ultrathin two-dimensional metal-organic framework nanosheets. Applied Catalysis B: Environmental, 227, 54-60
Open this publication in new window or tab >>Assembly of highly efficient photocatalytic CO2 conversion systems with ultrathin two-dimensional metal-organic framework nanosheets
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2018 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 227, p. 54-60Article in journal (Refereed) Published
Abstract [en]

An ultrathin two-dimensional Zn porphyrin-based metal-organic framework (Zn-MOF nanosheets) is developed and used for the first time in photoreduction of CO2 to CO. Consequently, two novelty noble-metal-free hybrid photocatalytic systems are established and displayed outstanding photocatalytic activity and selectivity for CO evolution under mild photocatalytic reaction conditions. The insight revealed Zn-MOF nanosheets as photo sensitizer displays a better charge transport ability and longer lifetime of the photogenerated electron-hole pairs than the Zn-MOF bulk, which are confirmed by photoelectrochemical impedance and photoluminescence (PL) measurements. These studies show that the development of noble-metal-free photocatalytic systems and various MOF-based materials for photocatalytic applications are promising.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
CO2 reduction, Photocatalysis, Metal-organic frameworks, Nanosheets, Zn porphyrin
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-226178 (URN)10.1016/j.apcatb.2018.01.028 (DOI)000428491000006 ()2-s2.0-85042913816 (Scopus ID)
Note

QC 20180516

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2018-05-16Bibliographically approved
Hou, J., Cao, S., Sun, Y., Wu, Y., Liang, F., Lin, Z. & Sun, L. (2018). Atomically Thin Mesoporous In2O3-x/In2S3 Lateral Heterostructures Enabling Robust Broadband-Light Photo-Electrochemical Water Splitting. Advanced Energy Materials, 8(9), Article ID 1701114.
Open this publication in new window or tab >>Atomically Thin Mesoporous In2O3-x/In2S3 Lateral Heterostructures Enabling Robust Broadband-Light Photo-Electrochemical Water Splitting
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2018 (English)In: Advanced Energy Materials, ISSN 1614-6832, Vol. 8, no 9, article id 1701114Article in journal (Refereed) Published
Abstract [en]

Atomically thin 2D heterostructures have opened new realms in electronic and optoelectronic devices. Herein, 2D lateral heterostructures of mesoporous In2O3-x/In2S3 atomic layers are synthesized through the in situ oxidation of In2S3 atomic layers by an oxygen plasma-induced strategy. Based on experimental observations and theoretical calculations, the prolonged charge carrier lifetime and increased electron density reveal the efficient photoexcited carrier transport and separation in the In2O3-x/In2S3 layers by interfacial bonding at the atomic level. As expected, the synergistic structural and electronic modulations of the In2O3-x/In2S3 layers generate a photocurrent of 1.28 mA cm(-2) at 1.23 V versus a reversible hydrogen electrode, nearly 21 and 79 times higher than those of the In2S3 atomic layers and bulk counterpart, respectively. Due to the large surface area, abundant active sites, broadband-light harvesting ability, and effective charge transport pathways, the In2O3-x/In2S3 layers build efficient pathways for photoexcited charge in the 2D semiconductive channels, expediting charge transport and kinetic processes and enhancing the robust broadband-light photo-electrochemical water splitting performance. This work paves new avenues for the exploration and design of atomically thin 2D lateral heterostructures toward robust photo-electrochemical applications and solar energy utilization.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
atomically thin layers, charge separation, In2O3-x/In2S3, lateral heterostructures, photo-electrochemical water splitting
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-226792 (URN)10.1002/aenm.201701114 (DOI)000429318400001 ()
Note

QC 20180521

Available from: 2018-05-21 Created: 2018-05-21 Last updated: 2018-05-21Bibliographically approved
Zhang, J., Daniel, Q., Zhang, T., Wen, X., Xu, B., Sun, L., . . . Cheng, Y.-B. (2018). Chemical Dopant Engineering in Hole Transport Layers for Efficient Perovskite Solar Cells: Insight into the Interfacial Recombination. ACS Nano, 12(10), 10452-10462
Open this publication in new window or tab >>Chemical Dopant Engineering in Hole Transport Layers for Efficient Perovskite Solar Cells: Insight into the Interfacial Recombination
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2018 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 10, p. 10452-10462Article in journal (Refereed) Published
Abstract [en]

Chemical doping of organic semiconductors has been recognized as an effective way to enhance the electrical conductivity. In perovskite solar cells (PSCs), various types of dopants have been developed for organic hole transport materials (HTMs); however, the knowledge of the basic requirements for being efficient dopants as well as the comprehensive roles of the dopants in PSCs has not been clearly revealed. Here, three copper-based complexes with controlled redox activities are applied as dopants in PSCs, and it is found that the oxidative reactivity of dopants presents substantial impacts on conductivity, charge dynamics, and solar cell performance. A significant improvement of open- circuit voltage (V-oc) by more than 100 mV and an increase of power conversion efficiency from 13.2 to 19.3% have been achieved by tuning the doping level of the HTM. The observed large variation of V-oc for three dopants reveals their different recombination kinetics at the perovskite/HTM interfaces and suggests a model of an interfacial recombination mechanism. We also suggest that the dopants in HTMs can also affect the charge recombination kinetics as well as the solar cell performance. Based on these findings, a strategy is proposed to physically passivate the electron- hole recombination by inserting an ultrathin Al2O3 insulating layer between the perovskite and the HTM. This strategy contributes a significant enhancement of the power conversion efficiency and environmental stability, indicating that dopant engineering is one crucial way to further improve the performance of PSCs.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
chemical dopants, hole transport materials, perovskite solar cells, interfacial recombination, passivation, Al2O3
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-239110 (URN)10.1021/acsnano.8b06062 (DOI)000448751800083 ()30207694 (PubMedID)2-s2.0-85053682102 (Scopus ID)
Note

QC 20181121

Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2018-11-21Bibliographically 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
Du, J., Li, F., Wang, Y., Zhu, Y. & Sun, L. (2018). Cu3P/CuO Core-Shell Nanorod Arrays as High-Performance Electrocatalysts for Water Oxidation. Chemelectrochem, 5(15), 2064-2068
Open this publication in new window or tab >>Cu3P/CuO Core-Shell Nanorod Arrays as High-Performance Electrocatalysts for Water Oxidation
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2018 (English)In: Chemelectrochem, ISSN 2196-0216, Vol. 5, no 15, p. 2064-2068Article in journal (Refereed) Published
Abstract [en]

Earth-abundant transition-metal-based oxides are potential candidates to replace the state-of-the-art noble-metal-based oxygen evolution catalysts (OECs) such as IrO2 and RuO2. Despite the low cost and large abundance, copper-based OER catalysts have been less frequently studied, mainly owing to the low electrical conductivity of copper oxides that results in large overpotential and sluggish kinetics for oxygen evolution. We report here the insitu fabrication of semi-metallic Cu3P nanorod arrays on commercial copper foam via a template approach; the resulting self-supported core-shell Cu-Cu3P/CuO electrode has the merits of high electrical conductivity, large active area, and short diffusion paths for electrolyte and evolved oxygen, exhibiting a low overpotential of 315mV and high durability over 50h at a current density of 10mAcm(-2) for OER in 1.0 M KOH. The remarkable OER performance reported here is not only superior to that of analogous Cu-CuO foam electrode, but also outperforms those of copper-based OER electrocatalysts in the literature.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
Electrocatalysts, oxygen evolution reaction, copper phosphide, core-shell nanorods
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-235139 (URN)10.1002/celc.201800323 (DOI)000440546600003 ()2-s2.0-85050962212 (Scopus ID)
Note

QC 20180919

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-10-16Bibliographically approved
Xu, P., Liu, P., Li, Y., Xu, B., Kloo, L., Sun, L. & Hua, Y. (2018). D-A-D-Typed Hole Transport Materials for Efficient Perovskite Solar Cells: Tuning Photovoltaic Properties via the Acceptor Group. ACS Applied Materials and Interfaces, 10(23), 19697-19703
Open this publication in new window or tab >>D-A-D-Typed Hole Transport Materials for Efficient Perovskite Solar Cells: Tuning Photovoltaic Properties via the Acceptor Group
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2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 23, p. 19697-19703Article in journal (Refereed) Published
Abstract [en]

Two D-A-D-structured hole-transport materials (YN1 and YN2) have been synthesized and used in perovskite solar cells. The two HTMs have low-lying HOMO levels and impressive mobility. Perovskite-based solar cells (PSCs) fabricated with YN2 showed a power conversion efficiency (PCE) value of 19.27% in ambient air, which is significantly higher than that of Spiro-OMeTAD (17.80%). PSCs based on YN1 showed an inferior PCE of 16.03%. We found that the incorporation of the stronger electron-withdrawing group in the HTM YN2 improves the PCE of PSCs. Furthermore, the YN2-based PSCs exhibit good long-term stability retaining 91.3% of its initial efficiency, whereas PSCs based on Spiro-OMeTAD retained only 42.2% after 1000 h lifetime (dark conditions). These promising results can provide a new strategy for the design of D-A-D HTMs for PSC applications in future.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
acceptor, hole-transport material, mobility, perovskite solar cells, spiro-OMeTAD
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-238197 (URN)10.1021/acsami.8b04003 (DOI)000435525100045 ()29785846 (PubMedID)2-s2.0-85047487298 (Scopus ID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationSwedish Energy Agency
Note

QC 20181119

Available from: 2018-11-19 Created: 2018-11-19 Last updated: 2018-11-19Bibliographically approved
Zhang, Y., Yang, X., Wang, W., Wang, X. & Sun, L. (2018). DDQ as an effective p-type dopant for the hole-transport material X1 and its application in stable solid-state dye-sensitized solar cells. Journal of Energy Challenges and Mechanics, 27(2), 413-418
Open this publication in new window or tab >>DDQ as an effective p-type dopant for the hole-transport material X1 and its application in stable solid-state dye-sensitized solar cells
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2018 (English)In: Journal of Energy Challenges and Mechanics, ISSN 2095-4956, E-ISSN 2056-9386, Vol. 27, no 2, p. 413-418Article in journal (Refereed) Published
Abstract [en]

X1 (MeO-TPD) is an inexpensive and easily synthesized pi-conjugated molecule that has been used as a hole-transport material (HTM) in solid-state dye-sensitized solar cells (ssDSSCs), achieving relatively high efficiency. In this paper, we characterize the physicochemical properties of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and show that it is a promising p-dopant in a spin-coating solution with X1 as the HTM. The doped ssDSSCs showed an increase in short-circuit current density from 5.38 mA cm(-2) to 7.39 mA cm(-2), and their overall power conversion efficiency increased from 2.9% to 4.3%. Also, ssDSSCs with DDQ-doped X1 were more stable than the undoped samples, demonstrating that DDQ can act as a p-type dopant in X1 as an HTM for highly efficient, stable ssDSSCs.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
p-Type dopant, X1, DDQ, ssDSSCs
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-224007 (URN)10.1016/j.jechem.2017.12.003 (DOI)000425896100012 ()2-s2.0-85038409600 (Scopus ID)
Note

QC 20180323

Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-03-23Bibliographically approved
Wang, L., Zhang, J., Liu, P., Xu, B., Zhang, B., Chen, H., . . . Sun, L. (2018). Design and synthesis of dopant-free organic hole-transport materials for perovskite solar cells. Chemical Communications, 54(69)
Open this publication in new window or tab >>Design and synthesis of dopant-free organic hole-transport materials for perovskite solar cells
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2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 69Article in journal (Refereed) Published
Abstract [en]

Two novel dopant-free hole-transport materials (HTMs) with spiro[dibenzo[c,h]xanthene-7,9-fluorene] (SDBXF) skeletons were prepared via facile synthesis routes. A power conversion efficiency of 15.9% in perovskite solar cells is attained by using one HTM without dopants, which is much higher than undoped Spiro-OMeTAD-based devices (10.8%). The crystal structures of both new HTMs were systematically investigated to reveal the reasons behind such differences in performance and to indicate the design principles of more advanced HTMs.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:kth:diva-234569 (URN)10.1039/c8cc04026e (DOI)000442605100002 ()30043013 (PubMedID)2-s2.0-85052539543 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20180917

Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2018-10-19Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-4521-2870

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