| 1. |
- Karlsson, Max, et al.
(författare)
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Mixed halide perovskites for spectrally stable and high-efficiency blue light-emitting diodes
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Bright and efficient blue emission is key to further development of metal halide perovskite light-emitting diodes. Although modifying bromide/chloride composition is straightforward to achieve blue emission, practical implementation of this strategy has been challenging due to poor colour stability and severe photoluminescence quenching. Both detrimental effects become increasingly prominent in perovskites with the high chloride content needed to produce blue emission. Here, we solve these critical challenges in mixed halide perovskites and demonstrate spectrally stable blue perovskite light-emitting diodes over a wide range of emission wavelengths from 490 to 451 nanometres. The emission colour is directly tuned by modifying the halide composition. Particularly, our blue and deep-blue light-emitting diodes based on three-dimensional perovskites show high EQE values of 11.0% and 5.5% with emission peaks at 477 and 467 nm, respectively. These achievements are enabled by a vapour-assisted crystallization technique, which largely mitigates local compositional heterogeneity and ion migration.
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| 2. |
- Kristanl, Matej, et al.
(författare)
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The Seventh Visual Object Tracking VOT2019 Challenge Results
- 2019
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Ingår i: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2019 is the seventh annual tracker benchmarking activity organized by the VOT initiative. Results of 81 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis as well as the standard VOT methodology for long-term tracking analysis. The VOT2019 challenge was composed of five challenges focusing on different tracking domains: (i) VOT-ST2019 challenge focused on short-term tracking in RGB, (ii) VOT-RT2019 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2019 focused on long-term tracking namely coping with target disappearance and reappearance. Two new challenges have been introduced: (iv) VOT-RGBT2019 challenge focused on short-term tracking in RGB and thermal imagery and (v) VOT-RGBD2019 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2019, VOT-RT2019 and VOT-LT2019 datasets were refreshed while new datasets were introduced for VOT-RGBT2019 and VOT-RGBD2019. The VOT toolkit has been updated to support both standard short-term, long-term tracking and tracking with multi-channel imagery. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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| 3. |
- Bhat, Goutam, et al.
(författare)
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NTIRE 2022 Burst Super-Resolution Challenge
- 2022
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Ingår i: 2022 IEEE/CVF CONFERENCE ON COMPUTER VISION AND PATTERN RECOGNITION WORKSHOPS (CVPRW 2022). - : IEEE. - 9781665487399 - 9781665487405 ; , s. 1040-1060
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Konferensbidrag (refereegranskat)abstract
- Burst super-resolution has received increased attention in recent years due to its applications in mobile photography. By merging information from multiple shifted images of a scene, burst super-resolution aims to recover details which otherwise cannot be obtained using a simple input image. This paper reviews the NTIRE 2022 challenge on burst super-resolution. In the challenge, the participants were tasked with generating a clean RGB image with 4x higher resolution, given a RAW noisy burst as input. That is, the methods need to perform joint denoising, demosaicking, and super-resolution. The challenge consisted of 2 tracks. Track 1 employed synthetic data, where pixel-accurate high-resolution ground truths are available. Track 2 on the other hand used real-world bursts captured from a handheld camera, along with approximately aligned reference images captured using a DSLR. 14 teams participated in the final testing phase. The top performing methods establish a new state-of-the-art on the burst super-resolution task.
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| 4. |
- Luo, Xiyu, et al.
(författare)
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Effects of local compositional heterogeneity in mixed halide perovskites on blue electroluminescence
- 2024
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Ingår i: Matter. - 2590-2393. ; 7:3, s. 1054-1070
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Tidskriftsartikel (refereegranskat)abstract
- Compositional heterogeneity is commonly observed in mixed bromide/iodide perovskite photoabsorbers, typically with minimal effects on charge carrier recombination and photovoltaic performance. Consistently, it has so far received very limited attention in bromide/chloride-mixed perovskites, which hold particular significance for blue light-emitting diodes. Here, we uncover that even a minor degree of localized halide heterogeneity leads to severe non-radiative losses in mixed bromide/chloride blue perovskite emitters, presenting a stark contrast to general observations in photovoltaics. We not only provide a visualization of the heterogeneity landscape spanning from micro-to sub-microscale but also identify that this issue mainly arises from the initially formed chloride-rich clusters during perovskite nucleation. Our work sheds light on a long-term neglected factor impeding the advancement of blue light-emitting diodes using mixed halide perovskites and provides a practical strategy to mitigate this issue.
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| 5. |
- Wang, Zhenqian, et al.
(författare)
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Northward migration of the East Asian summer monsoon northern boundary during the twenty-first century
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The northern fringe area of the East Asian summer monsoon (EASM) between arid and semiarid regions is a fragile eco-environment zone and ecological transition zone, and it is highly sensitive to climate change. Predicting the future migration of the northern boundary of the EASM is important for understanding future East Asian climate change and formulating of decisions on ecological protection and economic development in arid and semiarid regions. The reanalysis dataset and simulations of 23 models from the Coupled Models Intercomparison Project Phase 6 (CMIP6) were used to investigate the response of the boundary of the ESAM to the global warming. The multi-model ensemble showed a northwestward migration of the EASM northern boundary during the near-term (2020–2060) and late-term (2061–2099) of the twenty-first century under various Shared Socioeconomic Pathways (SSPs). The northern boundary migrated northwestward by 23–28 and 74–76 km in the near-term and late-term respectively, under SSP1-2.6, 2-4.5 and 3-7.0 and by ~ 44 km and ~ 107 km respectively during the near-term and late-term under SSP5-8.5. During the twenty-first century, under various SSPs, the surface of the East Asian subcontinent warmed more than the ocean, thereby increasing the contrast of near-surface temperature and sea level pressure in summer between the East Asian subcontinent and the surrounding oceans. In turn, the intensified land–sea thermal contrast reinforced the EASM meridional circulation and thus transported more moisture from the Indian Ocean into northern China. Additionally, a poleward migration and weakening of the East Asian subtropical westerly jet would also favor an increase in precipitation, eventually caused a northwestward migration of the EASM northern boundary. The results suggest that the arid and semiarid ecotone will become wetter, which could dramatically improve the eco-environment in the future.
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