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Bao, Qinye
Publications (10 of 19) Show all publications
Yang, J., Xiong, S., Qu, T., Zhang, Y., He, X., Guo, X., . . . Bao, Q. (2019). Extremely Low-Cost and Green Cellulose Passivating Perovskites for Stable and High-Performance Solar Cells. ACS Applied Materials and Interfaces, 11(14), 13491-13498
Open this publication in new window or tab >>Extremely Low-Cost and Green Cellulose Passivating Perovskites for Stable and High-Performance Solar Cells
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 14, p. 13491-13498Article in journal (Refereed) Published
Abstract [en]

The fast evolution of metal halide perovskite solar cells has opened a new chapter in the field of renewable energy. High-quality perovskite films as the active layers are essential for both high efficiency and long-term stability. Here, the perovskite films with enlarged crystal grain size and decreased defect density are fabricated by introducing the extremely low-cost and green polymer, ethyl cellulose (EC), into the perovskite layer. The addition of EC triggers hydrogen bonding interactions between EC and the perovskite, passivating the charge defect traps at the grain boundaries. The long chain of EC further acts as a scaffold for the perovskite structure, eliminating the annealing-induced lattice strain during the film fabrication process. The resulting devices with the EC additive exhibit a remarkably enhanced average power conversion efficiency from 17.11 to 19.27% and an improvement of all device parameters. The hysteresis index is found to decrease by three times from 0.081 to 0.027, which is attributed to suppressed ion migration and surface charge trapping. In addition, the defect passivation by EC significantly improves the environmental stability of the perovskite films, yielding devices that retain 80% of their initial efficiency after 30 days in ambient air at 45% relative humidity, whereas the pristine devices without EC fully degrade. This work provides a low-cost and green avenue for passivating defects that improves both the efficiency and operational stability of perovskite solar cells.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
cellulose; passivation; perovskite solar cells; efficiency; stability
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-157220 (URN)10.1021/acsami.9b01740 (DOI)000464769400049 ()30880387 (PubMedID)2-s2.0-85064109044 (Scopus ID)
Note

Funding Agencies|National Science Foundation of China [11604099, 21875067, 51873138, 51811530011]; Shanghai Science and Technology Innovation Action Plan [19QA1403100, 17JC1402500]; National Key Project for Basic Research of China [2017YFA0303403]; Swedish Research Council [2016-05498]; STINT grant [CH2017-7163]

Available from: 2019-06-13 Created: 2019-06-13 Last updated: 2019-06-18Bibliographically approved
Bao, Q., Liu, X., Braun, S., Yanqing, L., Jianxin, T., Chungang, D. & Fahlman, M. (2017). Intermixing Effect on Electronic Structures of TQ1:PC71BM Bulk Heterojunction in Organic Photovoltaics. Solar RRL, 1(10), Article ID 1700142.
Open this publication in new window or tab >>Intermixing Effect on Electronic Structures of TQ1:PC71BM Bulk Heterojunction in Organic Photovoltaics
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2017 (English)In: Solar RRL, ISSN 2367-198X, Vol. 1, no 10, article id 1700142Article in journal (Refereed) Published
Abstract [en]

The interface energetics and intermixing effects of the donor/acceptor bulk heterojunction (BHJ) blends of poly[2,3‐bis‐(3‐octyloxyphenyl) quinoxaline‐5, 8‐dilyl‐alt‐thiophene‐2, 5‐diyl]: [6,6]‐phenyl C71butyric acid methyl ester (TQ1:PC71BM) have been investigated using ultraviolet photoemission spectroscopy (UPS) in combination with the integer charge transfer model. The TQ1:PC71BM represents the useful model system for BHJ organic photovoltaics featuring effective charge generation and transport. It finds out that the positive integer charge state of TQ1 are equal in energy to the negative integer charge state of PC71BM, leading to a negligible potential step at TQ1:PC71BM interface and thus the vacuum level alignment. It is observed that the TQ1 accumulates on the top of TQ1:PC71BM BHJ and UPS spectra as function of various blend ratios suggest that the TQ1 mixes finely with PC71BM with the little work function modification in a wide range. In addition, no significant influence of the long‐range Coulomb interactions or the intermolecular hybridization on the occupied electronic structures is present for the well‐intermixed TQ1:PC71BM BHJs. These findings provide deep insights into the properties of BHJ blends and are beneficial for the performance optimization in organic photovoltaics.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2017
National Category
Physical Chemistry
Identifiers
urn:nbn:se:liu:diva-150513 (URN)10.1002/solr.201700142 (DOI)
Available from: 2018-08-23 Created: 2018-08-23 Last updated: 2019-01-09Bibliographically approved
Bao, Q., Fabiano, S., Andersson, M., Braun, S., Sun, Z., Crispin, X., . . . Fahlman, M. (2016). Energy Level Bending in Ultrathin Polymer Layers Obtained through Langmuir-Shafer Deposition. Advanced Functional Materials, 26(7), 1077-1084
Open this publication in new window or tab >>Energy Level Bending in Ultrathin Polymer Layers Obtained through Langmuir-Shafer Deposition
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2016 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 7, p. 1077-1084Article in journal (Refereed) Published
Abstract [en]

The semiconductor-electrode interface impacts the function and the performance of (opto) electronic devices. For printed organic electronics the electrode surface is not atomically clean leading to weakly interacting interfaces. As a result, solution-processed organic ultrathin films on electrodes typically form islands due to dewetting. It has therefore been utterly difficult to achieve homogenous ultrathin conjugated polymer films. This has made the investigation of the correct energetics of the conjugated polymer-electrode interface impossible. Also, this has hampered the development of devices including ultrathin conjugated polymer layers. Here, LangmuirShafer-manufactured homogenous mono-and multilayers of semiconducting polymers on metal electrodes are reported and the energy level bending using photoelectron spectroscopy is tracked. The amorphous films display an abrupt energy level bending that does not extend beyond the first monolayer. These findings provide new insights of the energetics of the polymer-electrode interface and opens up for new high-performing devices based on ultrathin semiconducting polymers.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2016
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering Biological Sciences
Identifiers
urn:nbn:se:liu:diva-126253 (URN)10.1002/adfm.201504729 (DOI)000371079300010 ()
Note

Funding Agencies|EU project SUNFLOWER of FP7 cooperation programme [287594]; Swedish Research Council [2013-4022]; Goran Gustafsson Foundation for Research in Natural Sciences and Medicine; Swedish Research Council Linnaeus grant LiLi-NFM; Advanced Functional Materials Center at Linkoping University

Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2017-11-30
Tang, Z., Liu, B., Melianas, A., Bergqvist, J., Tress, W., Bao, Q., . . . Zhang, F. (2015). A New Fullerene-Free Bulk-Heterojunction System for Efficient High-Voltage and High-Fill Factor Solution-Processed Organic Photovoltaics. Advanced Materials, 27(11), 1900-+
Open this publication in new window or tab >>A New Fullerene-Free Bulk-Heterojunction System for Efficient High-Voltage and High-Fill Factor Solution-Processed Organic Photovoltaics
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2015 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 27, no 11, p. 1900-+Article in journal (Refereed) Published
Abstract [en]

Small molecule donor/polymer acceptor bulk-heterojunction films with both compounds strongly absorbing have great potential for further enhancement of the performance of organic solar cells. By employing a newly synthesized small molecule donor with a commercially available polymer acceptor in a solution-processed fullerene-free system, a high power conversion efficiency of close to 4% is reported.

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2015
National Category
Biological Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-116947 (URN)10.1002/adma.201405485 (DOI)000351216500012 ()25645709 (PubMedID)
Note

Funding Agencies|Swedish Energy Agency; Knut and Alice Wallenberg foundation; Swedish research council (VR); Chinese scholarship council

Available from: 2015-04-10 Created: 2015-04-10 Last updated: 2017-12-04
Bao, Q., Liu, X., Braun, S., Gao, F. & Fahlman, M. (2015). Energetics at Doped Conjugated Polymer/Electrode Interfaces. ADVANCED MATERIALS INTERFACES, 2(2)
Open this publication in new window or tab >>Energetics at Doped Conjugated Polymer/Electrode Interfaces
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2015 (English)In: ADVANCED MATERIALS INTERFACES, ISSN 2196-7350, Vol. 2, no 2Article in journal (Refereed) Published
Abstract [en]

n/a

Place, publisher, year, edition, pages
Wiley: 12 months, 2015
National Category
Physical Sciences Biological Sciences
Identifiers
urn:nbn:se:liu:diva-114420 (URN)10.1002/admi.201400403 (DOI)000348287700008 ()
Note

Funding Agencies|EU [287594]; Swedish Research Council Linnaeus grant LiLi-NFM; Swedish Research Council [2013-4022]; Goran Gustafsson Foundation for Research in Natural Sciences and Medicine; Advanced Functional Materials Center at Linkoping University

Available from: 2015-03-02 Created: 2015-02-20 Last updated: 2015-06-05
Tang, Z., Elfwing, A., Melianas, A., Bergqvist, J., Bao, Q. & Inganäs, O. (2015). Fully-solution-processed organic solar cells with a highly efficient paper-based light trapping element. Journal of Materials Chemistry A, 3(48), 24289-24296
Open this publication in new window or tab >>Fully-solution-processed organic solar cells with a highly efficient paper-based light trapping element
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2015 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 48, p. 24289-24296Article in journal (Refereed) Published
Abstract [en]

We demonstrate the use of low cost paper as an efficient light-trapping element for thin film photovoltaics. We verify its use in fully-solution processed organic photovoltaic devices with the highest power conversion efficiency and the lowest internal electrical losses reported so far, the architecture of which - unlike most of the studied geometries to date - is suitable for upscaling, i.e. commercialization. The use of the paper-reflector enhances the external quantum efficiency (EQE) of the organic photovoltaic device by a factor of approximate to 1.5-2.5 over the solar spectrum, which rivals the light harvesting efficiency of a highly-reflective but also considerably more expensive silver mirror back-reflector. Moreover, by detailed theoretical and experimental analysis, we show that further improvements in the photovoltaic performance of organic solar cells employing PEDOT:PSS as both electrodes rely on the future development of high-conductivity and high-transmittance PEDOT:PSS. This is due optical losses in the PEDOT:PSS electrodes.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2015
National Category
Biological Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-123845 (URN)10.1039/c5ta07154b (DOI)000366163000014 ()
Note

Funding Agencies|Swedish Energy Agency; Knut and Alice Wallenberg Foundation through a Wallenberg Scholar grant; Knut and Alice Wallenberg Foundation through the project Power Papers

Available from: 2016-01-11 Created: 2016-01-11 Last updated: 2017-12-01
Bao, Q. (2015). Interface Phenomena in Organic Electronics. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Interface Phenomena in Organic Electronics
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Organic electronics based on organic semiconductors offer tremendous advantages compared to traditional inorganic counterparts such as low temperature processing, light weight, low manufacturing cost, high throughput and mechanical flexibility. Many key electronic processes in organic electronic devices, e.g. charge injection/extraction, charge recombination and exciton dissociation, occur at interfaces, significantly controlling performance and function. Understanding/modeling the interface energetics at organic-electrode/organic-organic heterojunctions is one of the crucial issues for organic electronic technologies to provide a route for improving device efficiency, which is the aim of the research presented in this thesis.

Integer charge transfer (ICT) states pre-existed in the dark and created as a consequence of Fermi level equilibrium at donor-acceptor interface have a profound effect on open circuit voltage in organic bulk heterojunction photovoltaics. ICT state formation causes vacuum level misalignment that yields a roughly constant effective donor ionization potential to acceptor electron affinity energy difference at the donor-acceptor interface, even though there is a large variation in electron affinity for the fullerene series. The large variation in open circuit voltage for the corresponding device series instead is found to be a consequence of trap-assisted recombination via integer charge transfer states. Based on the results, novel design rules for optimizing open circuit voltage and performance of organic bulk heterojunction solar cells are proposed.

Doping and insertion of interlayer are two established methods for enhancing charge injection/extraction properties at organic-electrode interface. By studying the energy level alignment behavior at low to intermediate doping levels for molecule-doped conjugated polymer/electrode interfaces, we deduce that two combined processes govern the interface energetics: (i) equilibration of the Fermi level due to oxidation (or reduction) of polymer sites at the interface as per the ICT model and (ii) a double dipole step induced by image charge from the dopant-polymer charge transfer complex that causes a shift of the work function. Such behavior is expected to hold in general for low to intermediate level doped organic semiconductor systems. The unified model is further extended to be suitable for conjugated electrolyte/electrode  interfaces, revealing the design rules for achieving the smallest charge injection/extraction barrier for both thin tunneling and thick charge transporting conjugated electrolyte interlayers.

To probe into the energy level spatial extension at interfaces, we employ the original approach of building and characterizing multilayers composed of a well-defined number of polymer monolayers with the Langmuir-Shäfer method to control polymer film uniformity and thicknesses, avoiding the problems associated with spin-coating ultrathin films. The disordered/amorphous films feature smaller, and in fact negligible, energy level bending compared to the more well-ordered films, in contradiction with existing models. It is found that that energy level bending depends on the ICT state distribution rather than the density of states of the neutral polymer chains in relation to the Fermi energy, thus taking into account the Coulomb energy associated with charging the polymer chain and transferring a charge across the interface. Based on this work, a general model for energy level bending in absence of significant doping of conjugated polymer films is proposed.

Organic semiconductors are sensitive to ambient atmosphere that can influence the energetics. The degradation effects of common PCBM film induced by oxygen and water are found to be completely different. Upon exposure to oxygen, the work function is down-shifted by ~ 0.15 eV compared to the ICT curve of the pristine PCBM film, originating from the weak interaction between the fullerene part of PCBM and oxygen, and this can be reversed by thermal treatment in vacuum. The down-shift in energetics will cause a loss in open circuit voltage at electrode interface, but aids free charge generation at donor-acceptor interface. Upon exposure to water, there is irreversible extensive broadening and bleaching of the valence electronic structure features as well as a substantial decrease of work function and ionization potential, severely degrading the transport properties.

Overall, the research results in this thesis thus give a deeper understanding of interface phenomena in organic electronics, especially regard to organic solar cells, aimed to further improve the device operation efficiency and lifetime.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. p. 56
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1658
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-118922 (URN)10.3384/diss.diva-118922 (DOI)978-91-7519-077-8 (ISBN)
Public defence
2015-08-27, Planck, Fysikhuset, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2015-06-05 Created: 2015-06-05 Last updated: 2019-11-15Bibliographically approved
Bao, Q., Liu, X., Wang, E., Fang, J., Gao, F., Braun, S. & Fahlman, M. (2015). Regular Energetics at Conjugated Electrolyte/Electrode Modifier for Organic Electronics and Their Implications of Design Rules. Advanced Materials Interfaces, 2(12), 1-6, Article ID 1500204.
Open this publication in new window or tab >>Regular Energetics at Conjugated Electrolyte/Electrode Modifier for Organic Electronics and Their Implications of Design Rules
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2015 (English)In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 2, no 12, p. 1-6, article id 1500204Article in journal (Refereed) Published
Abstract [en]

Regular energetics at a conjugated electrolyte/electrode modifier are found and controlled by equilibration of the Fermi level and an additional interface double dipole step induced by ionic functionality. Based on the results, design rules for conjugated electrolyte/electrode modifiers to achieve the smallest charge injection/exaction barrier and break through the current thickness limitation are proposed.

Place, publisher, year, edition, pages
John Wiley & Sons, 2015
Keywords
Conjugated electrolyte, electrode modifier, energetics, organic electronics
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-118917 (URN)10.1002/admi.201500204 (DOI)000360057500011 ()
Note

On the day of the defence date the status of this article was Manuscript.

Available from: 2015-06-05 Created: 2015-06-05 Last updated: 2017-03-16Bibliographically approved
Sun, Z., Shi, S., Bao, Q., Liu, X. & Fahlman, M. (2015). Role of Thick-Lithium Fluoride Layer in Energy Level Alignment at Organic/Metal Interface: Unifying Effect on High Metallic Work Functions. ADVANCED MATERIALS INTERFACES, 2(4), 1400527
Open this publication in new window or tab >>Role of Thick-Lithium Fluoride Layer in Energy Level Alignment at Organic/Metal Interface: Unifying Effect on High Metallic Work Functions
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2015 (English)In: ADVANCED MATERIALS INTERFACES, ISSN 2196-7350, Vol. 2, no 4, p. 1400527-Article in journal (Refereed) Published
Abstract [en]

The function of approximate to 3-nm thick lithium fluoride (LiF) buffer layers in combination with high work function metal contacts such as coinage metals and ferromagnetic metals for use in organic electronics and spintronics is investigated. The energy level alignment at the organic/LiF/metal interface is systematically studied using photoelectron spectroscopy and the integer charge transfer model. The thick-LiF buffer layer is found to pin the Fermi level to approximate to 3.8 eV, regardless of the work function of the initial metal due to energy level bending in the LiF layer caused by depletion of defect states. At 3-nm thickness, the LiF buffer layer provides full coverage, and the organic semiconductor adlayers are found to physisorb with the consequence that the energy level alignment at the organic/LiF interface follows the integer charge transfer models predictions.

Place, publisher, year, edition, pages
Wiley: 12 months, 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-117235 (URN)10.1002/admi.201400527 (DOI)000350756300005 ()
Note

Funding Agencies|European Commission [NMP3-SL-2011-263104]; SUNFLOWER (FP7-ICT-7) [287594]; Swedish Research Council [2013-4022]; Goran Gustafsson Foundation for Research in Natural Sciences and Medicine

Available from: 2015-04-22 Created: 2015-04-21 Last updated: 2015-06-03
Admassie, S., Elfwing, A., Jager, E., Bao, Q. & Inganäs, O. (2014). A renewable biopolymer cathode with multivalent metal ions for enhanced charge storage. JOURNAL OF MATERIALS CHEMISTRY A, 2(6), 1974-1979
Open this publication in new window or tab >>A renewable biopolymer cathode with multivalent metal ions for enhanced charge storage
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2014 (English)In: JOURNAL OF MATERIALS CHEMISTRY A, ISSN 2050-7488, Vol. 2, no 6, p. 1974-1979Article in journal (Refereed) Published
Abstract [en]

A ternary composite supercapacitor electrode consisting of phosphomolybdic acid (HMA), a renewable biopolymer, lignin, and polypyrrole was synthesized by a simple one-step simultaneous electrochemical deposition and characterized by electrochemical methods. It was found that the addition of HMA increased the specific capacitance of the polypyrrole-lignin composite from 477 to 682 F g(-1) ( at a discharge current of 1 A g(-1)) and also significantly improved the charge storage capacity from 6(to 128 mA h g(-1).

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2014
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-104646 (URN)10.1039/c3ta13876c (DOI)000329935700048 ()
Available from: 2014-02-20 Created: 2014-02-20 Last updated: 2018-01-25
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