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- Lu, Dongli, et al.
(författare)
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Inkjet-Printed Electron Transport Layers for Perovskite Solar Cells
- 2021
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 14:24, s. 7525-
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Tidskriftsartikel (refereegranskat)abstract
- Inkjet printing emerged as an alternative deposition method to spin coating in the field of perovskite solar cells (PSCs) with the potential of scalable, low-cost, and no-waste manufacturing. In this study, the materials TiO2, SrTiO3, and SnO2 were inkjet-printed as electron transport layers (ETLs), and the PSC performance based on these ETLs was optimized by adjusting the ink preparation methods and printing processes. For the mesoporous ETLs inkjet-printed from TiO2 and SrTiO3 nanoparticle inks, the selection of solvents for dispersing nanoparticles was found to be important and a cosolvent system is beneficial for the film formation. Meanwhile, to overcome the low current density and severe hysteresis in SrTiO3-based devices, mixed mesoporous SrTiO3/TiO2 ETLs were also investigated. In addition, inkjet-printed SnO2 thin films were fabricated by using a cosolvent system and the effect of the SnO2 ink concentrations on the device performance was investigated. In comparison with PSCs based on TiO2 and SrTiO3 ETLs, the SnO2-based devices offer an optimal power conversion efficiency (PCE) of 17.37% in combination with a low hysteresis. This work expands the range of suitable ETL materials for inkjet-printed PSCs and promotes the commercial applications of inkjet printing techniques in PSC manufacturing.
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- Lu, Dongli, 1990-
(författare)
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Inkjet-printed Functional Materials for Perovskite Solar Cells
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fabrication of lab-scale perovskite solar cells (PSCs) is dominated by the spin coating method, which wastes most of the precursor materials and is not compatible with large-scale manufacturing of PSCs. Inkjet printing provides a solution to upscaling of the fabrication of PSCs in a low-cost, waste-free, and sustainable way. In this thesis, we demonstrate the effectiveness of the inkjet technique in fabrication of functional materials for PSCs. The printing processes for depositing functional materials, i.e., electron transporting layers (ETLs), perovskite absorber layers as well as hole transporting layers (HTLs), are developed. We also strive to enhance the power conversion efficiency (PCE) of devices using the inkjet-printed ETLs and perovskite layers. Diverse measurements and analysis are conducted to provide insights into the enhancement mechanisms. The work undertaken in this thesis is presented as follows:The printing processes for depositing TiO2, SrTiO3, and SnO2 ETLs are developed. A cosolvent system is found to be beneficial for the formation of effective ETLs and the eventual device performance. A PCE of 17.37% is realized for the PSC device with an inkjet-printed SnO2 ETL, outperforming both the SrTiO3-based (15.73%) and TiO2-based (12.42%) devices.SnOx ETLs are synthesized and deposited via an inkjet printing process. The effects of the annealing temperature for post-processing of the deposited precursor layer on the properties of the resulting SnOx ETLs and their photovoltaic performance are discussed. The low-temperature amorphous SnOx ETLs outperform the high-temperature crystalline SnO2 ETLs, achieving a high PCE of 17.55%.Elemental doping is conducted to modify SnOx ETLs. Effects of doping on the properties of the SnOx ETLs and the ETL/perovskite interfaces are investigated in detail. Cu doping exerts a negative influence on the photovoltaic performance of SnOx ETLs. Surprisingly, a tunable hysteresis, transforming from normal hysteresis to inverted hysteresis, is observed with increasing Cu doping level. Ce doping leads to substantially improved properties. The incorporation of Ce into SnOx enables increased conductivity, improved energy level alignment at the ETL/perovskite interface, and suppressed recombination within the perovskite layer. The devices with Ce-doped SnOx ETLs achieve enhanced efficiency compared to the undoped devices. Interface modification is also performed using a bilayer ETL structure to modify the SnOx/perovskite interface. The effects of inserting a nanoparticle SnO2 (NP-SnO2) layer or a nanoparticle SrTiO3 (NP-STO) layer at the SnOx/perovskite interface are discussed.Perovskite films are deposited via inkjet printing under ambient conditions, which is a significant challenge for this humidity-sensitive material. A large-grained perovskite film with full surface coverage is realized using strategies of in-situ heat treatment, self-vapor-annealing treatment, and solvent engineering. The effects of these strategies on the nucleation and crystallization of perovskite films are discussed. A PCE of 13.44% is achieved for the all-inkjet-printed PSC device with an inkjet-printed ETL, an inkjet-printed perovskite layer, and an inkjet-printed HTL. The additive engineering strategy is also applied to hinder premature crystallization of the perovskite materials. The uniformity of the inkjet-printed perovskite layer is significantly improved although it is not directly conducive to photovoltaic performance.Overall, this thesis provides guidance in fabrication of effective functional materials via inkjet printing in a scalable and sustainable way.
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- Lu, Dongli, et al.
(författare)
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Inkjet-printed SnOx as an effective electron transport layer for planar perovskite solar cells and the effect of Cu doping
- 2024
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Ingår i: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- Inkjet printing is a more sustainable and scalable fabrication method than spin coating for producing perovskite solar cells (PSCs). Although spin-coated SnO2 has been intensively studied as an effective electron transport layer (ETL) for PSCs, inkjet-printed SnO(2 )ETLs have not been widely reported. Here, we fabricated inkjet-printed, solution-processed SnOx ETLs for planar PSCs. A champion efficiency of 17.55% was achieved for the cell using a low-temperature processed SnOx ETL. The low-temperature SnOx exhibited an amorphous structure and outperformed high-temperature crystalline SnO2. The improved performance was attributed to enhanced charge extraction and transport and suppressed charge recombination at ETL/perovskite interfaces, which originated from enhanced electrical and optical properties of SnOx, improved perovskite film quality, and well-matched energy level alignment between the SnOx ETL and the perovskite layer. Furthermore, SnOx was doped with Cu. Cu doping increased surface oxygen defects and upshifted energy levels of SnOx, leading to reduced device performance. A tunable hysteresis was observed for PSCs with Cu-doped SnOx ETLs, decreasing at first and turning into inverted hysteresis afterwards with increasing Cu doping level. This tunable hysteresis was related to the interplay between charge/ion accumulation and recombination at ETL/perovskite interfaces in the case of electron extraction barriers.
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- Peng, Qin, et al.
(författare)
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Assessment of bioavailability of selenium in different plant-soil systems by diffusive gradients in thin-films (DGT)
- 2017
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 225, s. 637-643
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Tidskriftsartikel (refereegranskat)abstract
- Uptake of selenium (Se) by plants largely depend on the availability of Se in soil. Soils and plants were sampled four times within 8 weeks of plant growth in pot experiments using four plant species. Sequential extraction and diffusive gradients in thin-films (DGT) method were employed to measure Se concentrations in potted soils in selenite- or selenate-amended soils. Results showed that DGT-measured Se concentrations (C-DGT-Se) were generally several folds higher for selenate than selenite amended soils, which were obviously affected by the plant species and the duration of their growth. For example, the folds in soil planted with mustard were 1.49-3.47 and those in soils planted with purple cabbage and broccoli, which grew for 3 and 4 weeks after sowing, were 1.06-2.14 and only 0.15-0.62 after 6 weeks of growth. The selenate-amended soil planted with wheat showed an extremely high C-DGT-Se compared with selenite-amended soil, except the last harvest. Furthermore, minimal changes in C-DGT-Se and soluble Se(IV) were found in selenite-amended soils during plant growth, whereas significant changes were observed in selenate-amended soils (p < 0.05). Additionally, Se distribution in various fractions of soil remarkably changed; the soils planted with purple cabbage and broccoli showed the most obvious change followed by wheat and mustard. Soluble Se(VI) and exchangeable Se(VI) were likely the major sources of C-DGT-Se in selenate-amended soils, and soluble Se(IV) was the possible source of C-DCT-Se in selenite-amended soils. In selenate-amended soils, soluble Se(VI) and exchangeable Se(VI) were significantly correlated with Se concentrations in purple cabbage, broccoli, and mustard; in wheat, Se concentration was significantly correlated only with soluble Se(VI) but not with exchangeable Se. C-DGT-Se eventually became positively correlated with Se concentrations accumulated by different plants, indicating that DGT is a feasible method in predicting plant uptake of selenate but not of selenite.
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