| 1. |
- Su, Yueling, et al.
(author)
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Carrier Generation Engineering toward 18% Efficiency Organic Solar Cells by Controlling Film Microstructure
- 2022
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In: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 12:19
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Journal article (peer-reviewed)abstract
- The single bulk-heterojunction active layer based on non-fullerene acceptors (NFAs) has dominated the power conversional efficiencies above 18% in state-of-the-art organic solar cells (OSCs). However, a deep understanding of the relationship between charge carrier process and film microstructure remains unclear for emerging NFA OSCs. Herein, with the superstar PM6:Y6 blend as a model, the charge generation process in active layers is successfully manipulated by designing three different film microstructures, and they are correlated with the final photovoltaic performance in OSC devices. The amount of intermediate intra-moiety excited states from the nanoscale Y6 aggregates can be effectively enhanced by controlling the phase separation domains and film crystallinity in the bicontinuous PM6:Y6 networks. This robustly improves the hole transfer, and thus promotes charge generation. As a result, the optimal films show superior device performance, that is, the high efficiencies of 16.53% and 17.98% for PM6:Y6- and D18:Y6-based single junction OSCs, respectively. The results presented here give a rational guide for optimizing the charge carrier process through controlling morphological microstructures toward high-performance NFA OSCs.
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| 2. |
- Jin, Bao, et al.
(author)
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Phase transition structural superlubricity
- 2024
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In: Matter. - : Cell Press. - 2590-2393 .- 2590-2385.
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Journal article (peer-reviewed)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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| 3. |
- Barrigon, Enrique, et al.
(author)
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Nanoprobe-Enabled Electron Beam Induced Current Measurements on III-V Nanowire-Based Solar Cells
- 2019
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In: 2019 IEEE 46th Photovoltaic Specialists Conference, PVSC 2019. - 0160-8371. - 9781728104942 ; , s. 2730-2733
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Conference paper (peer-reviewed)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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| 4. |
- Barrigón, Enrique, et al.
(author)
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Unravelling processing issues of nanowire-based solar cell arrays by use of electron beam induced current measurements
- 2020
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In: Nano Energy. - : Elsevier BV. - 2211-2855. ; 71
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Journal article (peer-reviewed)abstract
- III-V vertical nanowire arrays have great potential for next generation photovoltaics. Development towards high performing nanowire solar cells, which consist of a parallel connection of millions of single nanowire solar cells, requires a fast characterization technique that establishes a link between device performance and device processing. In this work, we use electron beam induced current measurements to characterize fully processed InP nanowire array solar cells at the nanoscale. Non-functional areas on fully processed devices can be quickly identified and processing induced effects on device performance can be clearly distinguished from those arising from nanowire growth. We identify how limiting factors on device performance are related to the processing procedures and provide a path to improve device performance further. In this way, electron beam induced current measurements become an essential tool for nanowire solar cell efficiency optimization, providing fast and useful information at the nanoscale and thus enabling up-scaling of the technology.
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| 5. |
- Hrachowina, Lukas, et al.
(author)
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Imaging the influence of oxides on the electrostatic potential of photovoltaic InP nanowires
- 2021
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In: Nano Research. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 14:11, s. 4087-4092
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Journal article (peer-reviewed)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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| 6. |
- Liu, Zhenchao, et al.
(author)
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Phase Interrogation Sensor Based on All-Dielectric BIC Metasurface
- 2023
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 23:22, s. 10441-10448
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Journal article (peer-reviewed)abstract
- The low performance of sensors based on an all-dielectric metasurface limits their application compared to metallic counterparts. Here, for the first time, an all-dielectric BIC (bound states in the continuum) metasurface is employed for highly sensitive phase interrogation refractive index sensing. The proposed sensor is well analyzed, fabricated, and characterized. Experimentally, a high-performance BIC-based microfluidic sensing chip with a Q factor of 1200 is achieved by introducing symmetry breaking. A refractive index sensor with high figure of merit of 418 RIU-1 is demonstrated, which is beneficial to the phase interrogation. Notably, we measure a record phase interrogation sensitivity of 2.7 x 10(4) deg/RIU to the refractive index, thus enabling the all-dielectric BIC to rival the refractive index detection capabilities of metal-based sensors such as surface plasmon resonance. This scheme establishes a pivotal role of the all-dielectric metasurface in the field of ultrahigh sensitivity sensors and opens possibilities for trace detection in biochemical analysis and environment monitoring.
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| 7. |
- Zhang, Yuwei, et al.
(author)
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Self-Limiting Polymer Exposure for Vertical Processing of Semiconductor Nanowire-Based Flexible Electronics
- 2020
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In: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 3:8, s. 7743-7749
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Journal article (peer-reviewed)abstract
- In this work, we demonstrate a vertical processing method to fabricate nanowire (NW)-based devices. This method combines the strong light absorption ability caused by the NW geometry and exposure to dose-dependent clearance properties of a photo-sensitive polymer. By embedding NW arrays in a polymer, the NW light absorption leads to self-limited exposure and selective removal of the polymer. This optical and self-limited exposure pattern definition method can replace more expensive processing equipment, such as reactive ion etching and the use of a mask aligner. Excitingly, this method can be used to enable peel-off of NW arrays from their parent substrate, opening up opportunities to fabricate flexible NW array devices.
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| 8. |
- Zhang, Yuwei, et al.
(author)
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UV exposure : A novel processing method to fabricate nanowire solar cells
- 2019
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In: 2019 IEEE 46th Photovoltaic Specialists Conference, PVSC 2019. - 0160-8371. - 9781728104942 ; , s. 2646-2648
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Conference paper (peer-reviewed)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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