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Zhu, Huimin
Publications (5 of 5) Show all publications
Wu, H., Zhu, H., Erbing, A., Johansson, M. B., Mukherjee, S., Man, G., . . . Johansson, E. (2019). Bandgap Tuning of Silver Bismuth Iodide via Controllable Bromide Substitution for Improved Photovoltaic Performance. ACS APPLIED ENERGY MATERIALS, 2(8), 5356-5362
Open this publication in new window or tab >>Bandgap Tuning of Silver Bismuth Iodide via Controllable Bromide Substitution for Improved Photovoltaic Performance
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2019 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 8, p. 5356-5362Article in journal (Refereed) Published
Abstract [en]

In this work, silver-bismuth-halide thin films, exhibiting low toxicity and good stability, were explored systemically by gradually substituting iodide, I, with bromide, Br, in the AgBi2I7 system. It was found that the optical bandgap can be tuned by varying the I/Br ratio. Moreover, the film quality was improved when introducing a small amount of Br. The solar cell was demonstrated to be more stable at ambient conditions and most efficient when incorporating 10% Br, as a result of decreased recombination originating from the increased grain size. Thus, replacing a small amount of I with Br was beneficial for photovoltaic performance.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
lead-free solar cells, power conversion efficiency, bandgap, silver bismuth iodide, mixed-halide composition, grain size, density functional theory
National Category
Physical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-391056 (URN)10.1021/acsaem.9b00914 (DOI)000483434700003 ()
Funder
Swedish Research CouncilSwedish Energy AgencyCarl Tryggers foundation
Available from: 2019-08-18 Created: 2019-08-18 Last updated: 2019-12-18Bibliographically approved
Johansson, M. B., Philippe, B., Banerjee, A., Phuyal, D., Mukherjee, S., Chakraborty, S., . . . Johansson, E. (2019). Cesium Bismuth Iodide Solar Cells from Systematic Molar Ratio Variation of CsI and BiI3. Inorganic Chemistry, 58(18), 12040-12052
Open this publication in new window or tab >>Cesium Bismuth Iodide Solar Cells from Systematic Molar Ratio Variation of CsI and BiI3
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2019 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 18, p. 12040-12052Article in journal (Refereed) Published
Abstract [en]

Metal halide compounds with photovoltaic properties prepared from solution have received increased attention for utilization in solar cells. In this work, low-toxicity cesium bismuth iodides are synthesized from solution, and their photovoltaic and, optical properties as well as electronic and crystal structures are investigated. The X-ray diffraction patterns reveal that a CsI/BiI3 precursor ratio of 1.5:1 can convert pure rhombohedral BiI3 to pure hexagonal Cs3Bi2I9, but any ratio intermediate of this stoichiometry and pure BiI3 yields a mixture containing the two crystalline phases Cs3Bi2I9 and BiI3, with their relative fraction depending on the CsI/BiI3 ratio. Solar cells from the series of compounds are characterized, showing the highest efficiency for the compounds with a mixture of the two structures. The energies of the valence band edge were estimated using hard and soft X-ray photoelectron spectroscopy for more bulk and surface electronic properties, respectively. On the basis of these measurements, together with UV-vis-near-IR spectrophotometry, measuring the band gap, and Kelvin probe measurements for estimating the work function, an approximate energy diagram has been compiled clarifying the relationship between the positions of the valence and conduction band edges and the Fermi level.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-395308 (URN)10.1021/acs.inorgchem.9b01233 (DOI)000486565600024 ()31483638 (PubMedID)
Funder
Swedish Energy AgencySwedish Research CouncilSwedish Research Council FormasSwedish Foundation for Strategic Research
Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2019-10-18Bibliographically approved
Zhu, H. (2019). Lead-free Metal Halide based Solar Cells. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Lead-free Metal Halide based Solar Cells
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Lead-halide perovskites have recently appeared as very promising materials for solar cells. However, their stability and toxicity may be limiting factors for their application. Therefore, to find new low toxic and high stability light harvesters may be necessary for overcoming the challenges of perovskite solar cells. The overall aim of this thesis is to explore new low toxic light harvesters and to investigate their possibility for application of solar cells. The focus in the thesis is on bismuth halide-based light harvesters, which show high light absorption coefficient and promising photovoltaic performance. Specifically, the investigated materials are different compositions of metal halides in which silver, Ag or cesium, Cs, are combined with bismuth, Bi, or antimony, Sb and the halides iodide, I, or bromide, Br. All of the systems show very promising optical performances, however, their photovoltaic performances are still low, which is partially due to the recombination and defects issues, etc. Through adjusting the elemental compositions by mixing Bi/Sb or I/Br the optical properties were tuned. By varying fabrication conditions or devices architectures, the results in this thesis also show that all the low toxic light harvesters works in solar cells, which possibly can be utilized in future photovoltaics.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. p. 79
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1840
Keywords
Low-toxicity, emerging light harvesters, lead-free, low toxic bismuth, Ag (Cs)-Bi (Sb)-I (Br) systems, 2D perovskites.
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-391058 (URN)978-91-513-0722-0 (ISBN)
Public defence
2019-10-04, Polhemsalen, Ångstrom 10134, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2019-09-12 Created: 2019-08-18 Last updated: 2019-10-15Bibliographically approved
Zhu, H., Johansson, M. B. & Johansson, E. M. .. (2018). The Effect of Dopant-Free Hole-Transport Polymers on Charge Generation and Recombination in Cesium-Bismuth-Iodide Solar Cells. ChemSusChem, 11(6), 1114-1120
Open this publication in new window or tab >>The Effect of Dopant-Free Hole-Transport Polymers on Charge Generation and Recombination in Cesium-Bismuth-Iodide Solar Cells
2018 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 11, no 6, p. 1114-1120Article in journal (Refereed) Published
Abstract [en]

The photovoltaic characteristics of CsBi3I10-based solar cells with three dopant-free hole-conducting polymers are investigated. The effect on charge generation and charge recombination in the solar cells using the different polymers is studied and the results indicate that the choice of polymer strongly affects the device properties. Interestingly, for the solar cell with poly[[2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl]-2,5-thiophenediyl] (TQ1), the photon-to-current conversion spectrum is highly improved in the red wavelength region, suggesting that the polymer also contributes to the photocurrent generation in this case. This report provides a new direction for further optimization of Bi-halide solar cells by using dopant-free hole-transporting polymers and shows that the energy levels and the interaction between the Bi-halide and the conducting polymers are very important for solar cell performance.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
bismuth, cesium bismuth iodide, htm, polymer, solar cells
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-354358 (URN)10.1002/cssc.201702169 (DOI)000428315300015 ()29372625 (PubMedID)
Funder
Swedish Energy AgencySwedish Research CouncilSwedish Research Council Formas
Available from: 2018-06-28 Created: 2018-06-28 Last updated: 2019-09-04Bibliographically approved
Johansson, M. B., Philippe, B., Banerjee, A., Phuyal, D., Chakraborty, S., Cameau, M., . . . Johansson, E. M. J.Cesium bismuth iodide, CsxBiyIz, solar cell compounds from systematic molar ratio variation.
Open this publication in new window or tab >>Cesium bismuth iodide, CsxBiyIz, solar cell compounds from systematic molar ratio variation
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(English)Manuscript (preprint) (Other academic)
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-369694 (URN)
Available from: 2018-12-16 Created: 2018-12-16 Last updated: 2018-12-19
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