| 1. |
- Barrigon, Enrique, et al.
(författare)
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Nanoprobe-Enabled Electron Beam Induced Current Measurements on III-V Nanowire-Based Solar Cells
- 2019
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Ingår i: 2019 IEEE 46th Photovoltaic Specialists Conference, PVSC 2019. - 0160-8371. - 9781728104942 ; , s. 2730-2733
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Konferensbidrag (refereegranskat)abstract
- Electron beam induced current (EBIC) is a well-established tool to, among others, locate and analyze p-n junctions, Schottky contacts or heterostructures in planar devices and is now becoming essential to study and optimize devices at the nanoscale, like III-V nanowire (NW) based solar cells. Here, we report on EBIC measurements on III-V single NW solar cells as well as on fully processed NW devices. This paper also highlights the importance of EBIC to optimize short circuit current density values of fully processed nanowire solar cells of 1 mm2.
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| 2. |
- Guo, Yuwei, et al.
(författare)
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Phenylalkylammonium passivation enables perovskite light emitting diodes with record high-radiance operational lifetime: the chain length matters
- 2021
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Ingår i: Nature Communications. - : Nature Research. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite light emitting diodes suffer from poor operational stability, exhibiting a rapid decay of external quantum efficiency within minutes to hours after turn-on. To address this issue, we explore surface treatment of perovskite films with phenylalkylammonium iodide molecules of varying alkyl chain lengths. Combining experimental characterization and theoretical modelling, we show that these molecules stabilize the perovskite through suppression of iodide ion migration. The stabilization effect is enhanced with increasing chain length due to the stronger binding of the molecules with the perovskite surface, as well as the increased steric hindrance to reconfiguration for accommodating ion migration. The passivation also reduces the surface defects, resulting in a high radiance and delayed roll-off of external quantum efficiency. Using the optimized passivation molecule, phenylpropylammonium iodide, we achieve devices with an efficiency of 17.5%, a radiance of 1282.8 W sr(-1) m(-2) and a record T-50 half-lifetime of 130h under 100mAcm(-2). Perovskite light emitting diodes suffer from operational stability, showing rapid decay of performance within minutes to hours after turn-on. Here, the authors investigate how the steric and Coulomb interaction of ammonium passivation molecules with varying alkyl chain length can improve device stability by suppressing iodide ion migration.
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| 3. |
- Hrachowina, Lukas, et al.
(författare)
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Imaging the influence of oxides on the electrostatic potential of photovoltaic InP nanowires
- 2021
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Ingår i: Nano Research. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 14:11, s. 4087-4092
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Tidskriftsartikel (refereegranskat)abstract
- Nanowires require surface passivation due to their inherent large surface to volume ratio. We investigate the effect of embedding InP nanowires in different oxides with respect to surface passivation by use of electron beam induced current measurements enabled by a nanoprobe based system inside a scanning electron microscope. The measurements reveal remote doping due to fixed charge carriers in the passivating POx/Al2O3 shell in contrast to results using SiOx. We used time-resolved photoluminescence to characterize the lifetime of charge carriers to evaluate the success of surface passivation. In addition, spatially resolved internal quantum efficiency simulations support and correlate the two applied techniques. We find that atomic-layer deposited POx/Al2O3 has the potential to passivate the surface of InP nanowires, but at the cost of inducing a field-effect on the nanowires, altering their electrostatic potential profile. The results show the importance of using complementary techniques to correctly evaluate and interpret processing related effects for optimization of nanowire-based optoelectronic devices. [Figure not available: see fulltext.].
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| 4. |
- Jin, Bao, et al.
(författare)
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Phase transition structural superlubricity
- 2024
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Ingår i: Matter. - : Cell Press. - 2590-2393 .- 2590-2385.
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Tidskriftsartikel (refereegranskat)abstract
- Structural superlubricity refers to a state with almost vanishing friction and wear between crystalline surfaces in incommensurate configurations. However, thus far, this phenomenon has been observed only at solid-solid interfaces. Here, we constructed an in situ heterojunction between a crystalline boundary tribofilm and a pressure-induced solid-phase 1–dodecanol molecular layer, achieving structural superlubricity in a liquid-solid interface. This novel superlubricity state, termed phase transition structural superlubricity (PTSS), is induced by incommensurate slip at the in situ heterojunction. Atomic force microscopy experiments and molecular dynamics simulations demonstrated that the friction of in situ heterojunction exhibits a periodicity of 180°. Notably, the PTSS arises when the molecular axis of 1–dodecanol is oriented 90° to the direction of friction. These findings provide a novel design strategy for structural superlubricity and bridge the gap between liquid and solid superlubricity, shedding substantial light upon achieving structural superlubricity across a broad range of environments.
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| 5. |
- Sharma, Sapna, et al.
(författare)
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A global database of lake surface temperatures collected by in situ and satellite methods from 1985–2009
- 2015
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Ingår i: Scientific Data. - : Macmillan Publishers Limited. - 2052-4463. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Global environmental change has influenced lake surface temperatures, a key driver of ecosystem structure and function. Recent studies have suggested significant warming of water temperatures in individual lakes across many different regions around the world. However, the spatial and temporal coherence associated with the magnitude of these trends remains unclear. Thus, a global data set of water temperature is required to understand and synthesize global, long-term trends in surface water temperatures of inland bodies of water. We assembled a database of summer lake surface temperatures for 291 lakes collected in situ and/or by satellites for the period 1985–2009. In addition, corresponding climatic drivers (air temperatures, solar radiation, and cloud cover) and geomorphometric characteristics (latitude, longitude, elevation, lake surface area, maximum depth, mean depth, and volume) that influence lake surface temperatures were compiled for each lake. This unique dataset offers an invaluable baseline perspective on global-scale lake thermal conditions as environmental change continues.
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| 6. |
- Wang, Yuyu, et al.
(författare)
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Potential influence of water level changes on energy flows in a lake food web
- 2011
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Ingår i: Chinese Science Bulletin. - : Springer Science and Business Media LLC. - 1001-6538 .- 1861-9541. ; 56:26, s. 2794-2802
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Tidskriftsartikel (refereegranskat)abstract
- Large seasonal water-level fluctuations may influence isotopic signatures of primary producers and the types and amounts of these potential food sources accessible to aquatic fauna of Poyang Lake, the largest freshwater lake in China. In this study, the isotopic signatures of primary producers and consumers were determined, stable carbon and nitrogen isotope analysis and mixing models were combined to investigate the influence of water levels on the diet and isotopic composition of Poyang Lake fish and invertebrates. Five potential food sources (seston, benthic organic matter, aquatic macrophytes, attached algae, and terrestrial plants), 4 species of invertebrates, and 10 species of fish were collected from the lake area during dry and wet seasons between January 2009 and April 2010. The delta C-13 values of invertebrates and most fish were within the range of delta C-13 values of the potential food sources for both seasons. The delta C-13 values of invertebrates and most fish were lower in the dry season than in the wet season, whereas the delta N-15 values exhibited different patterns for different species. Mixing models indicated that the most important food sources for common lake fauna were seston in the dry season and aquatic macrophytes and terrestrial plants in the wet season. The fauna were more omnivorous in the wet season than in the dry season. The food web dynamics of Poyang Lake are strongly influenced by changes in the abundance and accessibility of different basal food sources that occur because of seasonal flood pulses. The trophic links within the aquatic communities of Poyang Lake are modified by water-level fluctuations.
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| 7. |
- Zhang, Yuwei, et al.
(författare)
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UV exposure : A novel processing method to fabricate nanowire solar cells
- 2019
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Ingår i: 2019 IEEE 46th Photovoltaic Specialists Conference, PVSC 2019. - 0160-8371. - 9781728104942 ; , s. 2646-2648
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a novel and rapid method for nanowire (NW) solar cell processing. NW arrays were embedded in photoresist. The strong absorption of light in the NWs leads to self-limited exposure of the resist, which enables selective removal of the exposed part of the resist, opening up for the tips of the NWs and further processing. The UV-exposure technology allows a fast and low-cost process compared to the conventional reactive ion etching method.
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