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Tian, Lei
Publications (10 of 17) Show all publications
Tian, L. (2020). Exploring Dye-Sensitized Mesoporous NiO Photocathodes: from Mechanism to Applications. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Exploring Dye-Sensitized Mesoporous NiO Photocathodes: from Mechanism to Applications
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Increasing attention has been paid on solar energy conversion since the abundant solar energy possesses the potential to solve the problems on energy crisis and climate change. Dye-sensitized mesoporous NiO film was developed as one of the attractive photocathodes to fabricate p-type dye-sensitized solar cells (p-DSCs) and dye-sensitized photoelectrosynthetic cells (p-DSPECs) for electricity and chemical fuels generation, respectively. In this thesis, we designed a well-structured NiO-dye-TiO2 configuration by an atomic layer deposition (ALD) technique, with an organic dye PB6 as the photosensitizer. From kinetic studies of charge separation, ultrafast hole injection (< 200 fs) was observed from the excited state of PB6 dye into the valence band of NiO; dye regeneration (electron injection) was in t1/2 ≤ 500 fs, which is the fastest reported in any DSCs. On the basis of NiO-dye-TiO2 configuration, we successfully fabricated solid-state p-type DSCs (p-ssDSCs). Insertion of an Al2O3 layer was adopted to reduce charge recombination, i.e. NiO-dye-Al2O3-TiO2. Theoretically, such a configuration is possible to maintain efficient charge separation and depressed charge recombination. Based on NiO-dye-Al2O3-TiO2 configuration, the open-circuit voltage was improved to 0.48 V. Replacing electron conductor TiO2 with ZnO, short-circuit current density was increased to 680 μA·cm-2. The photocatalytic current density for H2 evolution was improve to 100 μA·cm-2 with a near unity of Faraday efficiency in p-DSPECs.

However, to further improve the performance of p-DSCs is very challenging. In p-ssDSCs, the limitation was confirmed from the poor electronically connection of the electron conductor (TiO2 or ZnO) inside the NiO-dye films. We further investigated the electronic property of surface states on mesoporous NiO film. We found that the surface sates, not the bulk, on NiO determined the conductivity of the mesoporous NiO films. The dye regeneration in liquid p-DSCs with I-/I3- as redox couples was significantly affected by surface states. A more complete mechanism is suggested to understand a particular hole transport behavior reported in p-DSCs, where hole transport time is independent on light intensity. The independence of charge transport is ascribed to the percolation effect in the hole hopping on the surface states.

 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2020. p. 73
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1896
Keywords
NiO, p-type, dye-sensitized solar cells, solid state, charge separation, charge recombination, charge diffusion, transport time, surface states, electron conductor, dye regeneration
National Category
Physical Chemistry
Research subject
Chemistry with specialization in Chemical Physics
Identifiers
urn:nbn:se:uu:diva-402415 (URN)978-91-513-0852-4 (ISBN)
Public defence
2020-03-03, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2020-02-11 Created: 2020-01-15 Last updated: 2020-02-14
Huang, J., Xu, B., Tian, L., Pati, P. B., Etman, A. S., Sun, J., . . . Tian, H. (2019). A heavy metal-free CuInS2 quantum dot sensitized NiO photocathode with a Re molecular catalyst for photoelectrochemical CO2 reduction. Chemical Communications, 55(55), 7918-7921
Open this publication in new window or tab >>A heavy metal-free CuInS2 quantum dot sensitized NiO photocathode with a Re molecular catalyst for photoelectrochemical CO2 reduction
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2019 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, no 55, p. 7918-7921Article in journal (Refereed) Published
Abstract [en]

Heavy metal-free CuInS2 quantum dots (QDs) were employed as a photosensitizer on a NiO photocathode to drive an immobilized molecular Re catalyst for photoelectrochemical CO2 reduction for the first time. A photocurrent of 25 mu A cm(-2) at -0.87 V vs. NHE was obtained, providing a faradaic efficiency of 32% for CO production.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-390783 (URN)10.1039/c9cc04222a (DOI)000474306200003 ()31215919 (PubMedID)
Funder
Swedish Energy Agency, 11674-8Göran Gustafsson Foundation for Research in Natural Sciences and MedicineStiftelsen Olle Engkvist Byggmästare
Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
Xu, B., Wrede, S., Curtze, A., Tian, L., Pati, P. B., Kloo, L., . . . Tian, H. (2019). An Indacenodithieno[3,2-b]thiophene-Based Organic Dye for Solid-State p-Type Dye-Sensitized Solar Cells. ChemSusChem, 12(14), 3243-3248
Open this publication in new window or tab >>An Indacenodithieno[3,2-b]thiophene-Based Organic Dye for Solid-State p-Type Dye-Sensitized Solar Cells
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2019 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 12, no 14, p. 3243-3248Article in journal (Refereed) Published
Abstract [en]

An indacenodithieno[3,2-b]thiophene (IDTT) unit is used as a linker moiety to design a new p-type dye-TIP-for solid-state p-type dye-sensitized solar cells. Solar cells based on the TIP dye offered an efficiency of 0.18 % with an open-circuit photovoltage of 550 mV and a short-circuit photocurrent density of 0.86 mA cm(-2), which is better than those of two reference dyes, PB6 and BH4. Charge lifetime experiments reveal that the IDTT linker-based TIP dye significantly suppresses charge recombination losses in the devices.

Keywords
dye-sensitized solar cells, energy materials, p-type dye, S heterocycles, solid state
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-393128 (URN)10.1002/cssc.201901102 (DOI)000478633900003 ()31144448 (PubMedID)
Funder
Swedish Energy Agency, 43599-1Stiftelsen Olle Engkvist Byggmästare
Available from: 2019-09-24 Created: 2019-09-24 Last updated: 2019-09-24Bibliographically approved
Jia, D., Chen, J., Zheng, S., Phuyal, D., Yu, M., Tian, L., . . . Zhang, X. (2019). Highly Stabilized Quantum Dot Ink for Efficient Infrared Light Absorbing Solar Cells. ADVANCED ENERGY MATERIALS, 9(44), Article ID 1902809.
Open this publication in new window or tab >>Highly Stabilized Quantum Dot Ink for Efficient Infrared Light Absorbing Solar Cells
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2019 (English)In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 9, no 44, article id 1902809Article in journal (Refereed) Published
Abstract [en]

Liquid-state ligand exchange provides an efficient approach to passivate a quantum dot (QD) surface with small binding species and achieve a QD ink toward scalable QD solar cell (QDSC) production. Herein, experimental studies and theoretical simulations are combined to establish the physical principles of QD surface properties induced charge carrier recombination and collection in QDSCs. Ammonium iodide (AI) is used to thoroughly replace the native oleic acid ligand on the PbS QD surface forming a concentrated QD ink, which has high stability of more than 30 d. The ink can be directly applied for the preparation of a thick QD solid film using a single deposition step method and the QD solid film shows better characteristics compared with that of the film prepared with the traditional PbX2 (X = I or Br) post-treated QD ink. Infrared light-absorbing QDSC devices are fabricated using the PbS-AI QD ink and the devices give a higher photovoltaic performance compared with the devices fabricated with the traditional PbS-PbX2 QD ink. The improved photovoltaic performance in PbS-AI-based QDSC is attributed to diminished charge carrier recombination induced by the sub-bandgap traps in QDs. A theoretical simulation is carried out to atomically link the relationship of QDSC device function with the QD surface properties.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
charge recombination, ligand exchange, quantum dots, solar cells, theoretical simulations
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-408483 (URN)10.1002/aenm.201902809 (DOI)000490644300001 ()
Funder
Swedish Energy Agency
Available from: 2020-04-07 Created: 2020-04-07 Last updated: 2020-04-07Bibliographically approved
Liu, J., Zhou, Q., Kyi Thein, N., Tian, L., Jia, D., Johansson, E. M. J. & Zhang, X. (2019). In situ growth of perovskite stacking layers for high-efficiency carbon-based hole conductor free perovskite solar cells. Journal of Materials Chemistry A, 7(22), 13777-13786
Open this publication in new window or tab >>In situ growth of perovskite stacking layers for high-efficiency carbon-based hole conductor free perovskite solar cells
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2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 22, p. 13777-13786Article in journal (Refereed) Published
Abstract [en]

The interfacial properties between a perovskite layer and carbon electrode are critical for the photovoltaic performance of carbon electrode-based perovskite solar cells (PSCs). Herein, a methylammonium lead mixed halide (MAPbIxBr3−x) perovskite layer is in situ grown on the top of a methylammonium lead iodide (MAPbI3) perovskite layer forming a MAPbI3/MAPbIxBr3−x perovskite stacking structure (PSS) to improve the interfacial properties at the perovskite/carbon electrode interface. The charge carrier dynamics in both the perovskite and the PSC device induced by the MAPbIxBr3−x perovskite stacking layer are studied using extensive characterization. The charge interfacial recombination at the perovskite/carbon electrode interface is significantly diminished using the PSS within the PSC, resulting in largely improved charge extraction and therefore high photovoltaic performance. The PSS-based PSC shows a power conversion efficiency of up to 16.2% (increased by 43% compared with that of a conventional MAPbI3-based PSC), which is among the highest efficiencies of carbon electrode-based hole conductor free PSCs. Meanwhile, the PSS-based PSC also exhibits good stability under both continuous illumination and storage under dark conditions. This work may provide a new avenue to fine tune the interfacial properties of carbon electrode-based PSCs for further improving their photovoltaic performance.

National Category
Materials Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-388769 (URN)10.1039/c9ta02772f (DOI)000470928800035 ()
Funder
Swedish Energy AgencySwedish Research Council FormasSwedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of Technology
Available from: 2019-07-05 Created: 2019-07-05 Last updated: 2019-07-05Bibliographically approved
Tian, L., Törndahl, T., Ling, J., Pati, P. B., Zhang, Z.-B., Kubart, T., . . . Tian, H. (2019). Mechanistic Insights into Solid-State p-Type Dye-Sensitized Solar Cells. The Journal of Physical Chemistry C, 123(43), 26151-26160
Open this publication in new window or tab >>Mechanistic Insights into Solid-State p-Type Dye-Sensitized Solar Cells
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2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 43, p. 26151-26160Article in journal (Refereed) Published
Abstract [en]

The study of p-type dye sensitized solar cells (p-DSCs) is appealing but challenging. Although the devices have been studied for 20 years, the light conversion efficiency lags far behind those of n-DSCs. Very recently, on the basis of a core-shell structure, a novel solid-state p-DSC (p-ssDSCs) has been fabricated, which showed great enhancement in open-circuit voltage and dye regeneration rate. To further improve the performance of such devices, charge diffusion, recombination process, and the main limiting factors have to be understood. In the present paper, core-shell p-ssDSCs with ZnO as an electron conductor were fabricated by atomic layer deposition. The charge transport time was determined to be ca. 0.1 ms, which is about 2 orders of magnitude faster than those of typical liquid devices with I-/I-3(-) as a redox mediator. As a consequence, the devices exhibit the highest reported charge diffusion coefficient (D-d)' among p-DSCs. It is ascribed to an electron-limiting diffusion process by the ambipolar diffusion model, suggesting a different charge-transport-determining mechanism in contrast to liquid p-DSCs. The charge recombination rate is 1-2 orders of magnitude slower than its charge transport time, mandating that the estimated charge collection efficiency is near unity. Detailed analysis of the incident photon-to-electron conversion efficiency suggests that the energy conversion efficiency in these p-ssDSCs is currently limited by a large fraction of dyes that is not fully electrically connected in the device.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Physical Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-397591 (URN)10.1021/acs.jpcc.9b08251 (DOI)000493865700013 ()
Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2020-01-15Bibliographically approved
Xu, B., Tian, L., Etman, A. S., Sun, J. & Tian, H. (2019). Solution-processed nanoporous NiO-dye-ZnO photocathodes: Toward efficient and stable solid-state p-type dye-sensitized solar cells and dye-sensitized photoelectrosynthesis cells. Nano Energy, 55, 59-64
Open this publication in new window or tab >>Solution-processed nanoporous NiO-dye-ZnO photocathodes: Toward efficient and stable solid-state p-type dye-sensitized solar cells and dye-sensitized photoelectrosynthesis cells
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2019 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 55, p. 59-64Article in journal (Refereed) Published
Abstract [en]

A solution-processed NiO-dye-ZnO photocathode was developed for applications in both solid-state p-type dye-sensitized solar cells (p-ssDSCs) and p-type dye-sensitized photoelectrosynthesis cells (p-DSPECs). In p-ssDSCs, the solar cell using ZnO as electron transport material showed a short circuit current, up to 680 mu A cm(-2), which is 60-fold larger than that previously reported device using TiO2 as electron transport material with similar architecture. In the p-DSPECs, a remarkable photocurrent of 100 mu A cm(-2) was achieved in a pH = 5.0 acetate buffer solution under a bias potential at 0.05 V vs RHE with platinum as the proton reduction catalyst. A Faradaic efficiency approaching 100% for the H-2 evolution reaction was obtained after photoelectrolysis for 9 h. Importantly, the solution-processed NiO-dye-ZnO photocathode exhibited excellent long-term stability in both p-ssDSCs and p-DSPECs. To the best of our knowledge, this is the first study where a solution-processable, nanoporous NiO-dye-ZnO photocathode is used for both p-ssDSCs and p-DSPECs having both excellent device performance and stability.

Keywords
Dye-sensitized photocathode, P-type, Solution-processed, Solid-state, Solar cell, Solar fuel
National Category
Materials Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-374114 (URN)10.1016/j.nanoen.2018.10.054 (DOI)000454636200007 ()
Funder
Swedish Energy Agency, 43599-1Swedish Energy Agency, 11674-8
Note

Bo Xu and Lei Tian contributed equally to this work.

Available from: 2019-01-23 Created: 2019-01-23 Last updated: 2020-01-15Bibliographically approved
Huang, J., Gilbert Gatty, M., Xu, B., Pati, P. B., Etman, A. S., Tian, L., . . . Tian, H. (2018). Covalently linking CuInS2 quantum dots with a Re catalyst by click reaction for photocatalytic CO2 reduction. Dalton Transactions, 47(31), 10775-10783
Open this publication in new window or tab >>Covalently linking CuInS2 quantum dots with a Re catalyst by click reaction for photocatalytic CO2 reduction
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2018 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 47, no 31, p. 10775-10783Article in journal (Refereed) Published
Abstract [en]

Covalently linking photosensitizers and catalysts in an inorganic-organic hybrid photocatalytic system is beneficial for efficient electron transfer between these components. However, general and straightforward methods to covalently attach molecular catalysts on the surface of inorganic semiconductors are rare. In this work, a classic rhenium bipyridine complex (Re catalyst) has been successfully covalently linked to the low toxicity CuInS2 quantum dots (QDs) by click reaction for photocatalytic CO2 reduction. Covalent bonding between the CuInS2 QDs and the Re catalyst in the QD-Re hybrid system is confirmed by UV-visible absorption spectroscopy, Fourier-transform infrared spectroscopy and energy-dispersive X-ray measurements. Time-correlated single photon counting and ultrafast time-resolved infrared spectroscopy provide evidence for rapid photo-induced electron transfer from the QDs to the Re catalyst. Upon photo-excitation of the QDs, the singly reduced Re catalyst is formed within 300 fs. Notably, the amount of reduced Re in the linked hybrid system is more than that in a sample where the QDs and the Re catalyst are simply mixed, suggesting that the covalent linkage between the CuInS2 QDs and the Re catalyst indeed facilitates electron transfer from the QDs to the Re catalyst. Such an ultrafast electron transfer in the covalently linked CuInS2 QD-Re hybrid system leads to enhanced photocatalytic activity for CO2 reduction, as compared to the conventional mixture of the QDs and the Re catalyst.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-363108 (URN)10.1039/c8dt01631c (DOI)000441151700051 ()30019727 (PubMedID)
Funder
Swedish Research CouncilSwedish Energy AgencyGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyStiftelsen Olle Engkvist Byggmästare
Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2018-10-15Bibliographically approved
Tian, H., Nemeth, B., Berggren, G. & Tian, L. (2018). Hydrogen evolution by a photoelectrochemical cell based on a Cu2O-ZnO-[FeFe] hydrogenase electrode. Journal of Photochemistry and Photobiology A: Chemistry, 366, 27-33
Open this publication in new window or tab >>Hydrogen evolution by a photoelectrochemical cell based on a Cu2O-ZnO-[FeFe] hydrogenase electrode
2018 (English)In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 366, p. 27-33Article in journal (Refereed) Published
Abstract [en]

A Cu2O-ZnO-hydrogenase photocathode possessed enzyme/semiconductor junction has been constructed by immobilizing a biological protein catalyst, hydrogenase-CrHydA1 enzyme on the ZnO protected Cu2O electrode. With light illumination, a photocurrent of 0.8 mA/cm2 at 0.15 V vs. RHE was obtained and hydrogen was successfully detected from the photocathode in photoelectrochemical measurements with Faradaic efficiency of ca. 1%. The construction as well as the stability of the system are also reported. The result shows that this biohybrid photocathode is capable of photocatalytic proton reduction under mild conditions.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-371529 (URN)10.1016/j.jphotochem.2018.01.035 (DOI)000452577600005 ()
Funder
Stiftelsen Olle Engkvist Byggmästare, 2015/456J. Gust. Richert stiftelse, 2016-00231Swedish Energy Agency, 111674-8Swedish Research Council, 621-2014-5670Swedish Research Council Formas, 213-2014-880Wenner-Gren Foundations
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2019-01-16Bibliographically approved
Zhang, X., Zhang, J., Phuyal, D., Du, J., Tian, L., Öberg, V. A., . . . Johansson, E. M. J. (2018). Inorganic CsPbI3 Perovskite Coating on PbS Quantum Dot for Highly Efficient and Stable Infrared Light Converting Solar Cells. Advanced Energy Materials, 8(6), Article ID 1702049.
Open this publication in new window or tab >>Inorganic CsPbI3 Perovskite Coating on PbS Quantum Dot for Highly Efficient and Stable Infrared Light Converting Solar Cells
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2018 (English)In: Advanced Energy Materials, ISSN 1614-6832, Vol. 8, no 6, article id 1702049Article in journal (Refereed) Published
Abstract [en]

Solution-processed colloidal quantum dot (CQD) solar cells harvesting the infrared part of the solar spectrum are especially interesting for future use in semitransparent windows or multilayer solar cells. To improve the device power conversion efficiency (PCE) and stability of the solar cells, surface passivation of the quantum dots is vital in the research of CQD solar cells. Herein, inorganic CsPbI3 perovskite (CsPbI3-P) coating on PbS CQDs with a low-temperature, solution-processed approach is reported. The PbS CQD solar cell with CsPbI3-P coating gives a high PCE of 10.5% and exhibits remarkable stability both under long-term constant illumination and storage under ambient conditions. Detailed characterization and analysis reveal improved passivation of the PbS CQDs with the CsPbI3-P coating, and the results suggest that the lattice coherence between CsPbI3-P and PbS results in epitaxial induced growth of the CsPbI3-P coating. The improved passivation significantly diminishes the sub-bandgap trap-state assisted recombination, leading to improved charge collection and therefore higher photovoltaic performance. This work therefore provides important insight to improve the CQD passivation by coating with an inorganic perovskite ligand for photovoltaics or other optoelectronic applications.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
charge recombination, inorganic perovskite, quantum dots, solar cells, surface passivation
National Category
Physical Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-348982 (URN)10.1002/aenm.201702049 (DOI)000426152400017 ()
Funder
Swedish Energy AgencySwedish Research CouncilSwedish Research Council Formas
Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2020-02-20Bibliographically approved
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