| 1. |
- Pan, Kui, et al.
(författare)
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Highly effective transfer of micro-LED pixels to the intermediate and rigid substrate with weak and tunable adhesion by thiol modification
- 2023
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 15:9, s. 4420-4428
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Tidskriftsartikel (refereegranskat)abstract
- Based on transfer printing technology, micro-LED pixels can be transferred to different types and sizes of driving substrates to realize displays with different application scenarios. To achieve a successful transfer, GaN-based micro-LEDs first need to be separated from the original epitaxial substrate. Here, micro-LED pixels (each size 25 μm × 30 μm) on the sapphire substrate were transferred to a flexible semiconductor wafer processing (SWP) tape that is strongly sticky by conventional laser lift-off (LLO) techniques. The pixels on the SWP tape were then transferred by using a sacrificial layer of non-crosslinked oligomeric polystyrene (PS) film onto the intermediate and rigid substrate (IRS) with weak and tunable adhesion by thiol (-SH) modification. The electrode of the micro-LED is Au metal, which forms Au-S bonds with the surface of the IRS to fix the pixels. The rigid substrate helps ensure that the pixel spacing is almost unchanged during the stamp transfer process, and the weak and tunable adhesion facilitates the pixels being picked up by the stamp. The experimental results demonstrate that the pixels can be efficiently transferred to the IRS by LLO and sacrificial layer-assistance, which will provide the possibility of achieving the further transfer of pixels to different types and sizes of driving substrates by a suitable transfer stamp. The transfer process details are discussed, which can provide insights into the transfer of micro-nano devices through polymer sacrificial layers.
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| 2. |
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| 3. |
- Yang, Guoliang, et al.
(författare)
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Using multi-level frontiers in DEA models to grade countries/territories
- 2016
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Ingår i: Journal of Informetrics. - : Elsevier. - 1751-1577 .- 1875-5879. ; 10:1, s. 238-253
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Tidskriftsartikel (refereegranskat)abstract
- Several investigations to and approaches for categorizing academic journals/institutions/countries into different grades have been published in the past. To the best of our knowledge, most existing grading methods use either a weighted sum of quantitative indicators (including the case of one properly defined quantitative indicator) or quantified peer review results. Performance measurement is an important issue of concern for science and technology (S&T) management. In this paper we address this issue, leading to multi-level frontiers resulting from data envelopment analysis (DEA) models to grade selected countries/territories. We use research funding and researchers as input indicators, and take papers, citations and patents as output indicators. Our research results show that using DEA frontiers we can unite countries/territories by different grades. These grades reflect the corresponding countries' levels of performance with respect to multiple inputs and outputs. Furthermore, we use papers, citations and patents as single output (with research funding and researchers as inputs), respectively, to show country/territory grade changes. In order to increase the insight in this approach, we also incorporate a simple value judgment (that the number of citations is more important than the number of papers) as prior information into the DEA models to study the resulting changes of these Countries/Territories' performance grades.
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| 4. |
- Ahlgren, Per, et al.
(författare)
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The role of the Chinese Key Labs in the international and national scientific arena revisited
- 2017
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Ingår i: Research Evaluation. - : OXFORD UNIV PRESS. - 0958-2029 .- 1471-5449. ; 26:2, s. 132-143
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Tidskriftsartikel (refereegranskat)abstract
- In this contribution, which builds on and develops a study that was published more than 10 years ago, we address the role of the Chinese Key Labs (KLs) in the international and national scientific arena. We give a short overview of the position of KLs in China, including their budget and manpower. Based on large numbers of Chinese publications obtained from the Web of Science (WoS) and the Chinese Science Citation Database (CSCD), the KLs are compared across publication years to the rest of China (ChRest) with respect to publication output and citation impact. We also look at collaboration in terms of co-publishing between the KLs and the ChRest. As to publications in the WoS, we found that the contribution of KLs compared with the ChRest is slightly and irregularly increasing (using full counting as well as fractional counting), whereas a stronger increasing trend is observed for the corresponding contribution in the CSCD. We observed an increase in the number of collaborations between KLs and Chinese colleagues, regardless of database. For WoS and field normalized citation indicators, we obtained the expected results that researchers at KLs perform considerably better than other Chinese colleagues and, moreover, perform clearly better than database average. As such we may conclude that KLs have lived up to their promise and made real impact on the international arena.
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| 5. |
- Ding, Jielan, et al.
(författare)
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Disciplinary structures in Nature, Science and PNAS : journal and country levels
- 2018
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Ingår i: Scientometrics. - : SPRINGER. - 0138-9130 .- 1588-2861. ; 116:3, s. 1817-1852
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Tidskriftsartikel (refereegranskat)abstract
- This paper analyzes, using Web of Science publications and two time periods (2004-2006 and 2014-2016), the disciplinary structures in the three prestigious journals Nature, Science and PNAS, compared with two baselines: Non-NSP_Multi (multidisciplinary publications that have other source journals than Nature, Science and PNAS), and Non-Multi (publications assigned to other categories than Multidisciplinary). We analyze the profiles at two levels, journal and country. The results for the journal level show that for Nature and Science, the publications are considerably less concentrated to certain disciplines compared to PNAS. Biology is the dominant discipline for all the three journals. Nature and Science have similar publication shares in Medicine, Geosciences, Physics, Space science, and Chemistry. The publications of PNAS are highly concentrated to two disciplines: Biology and Medicine. Compared with Non-NSP_Multi and Non-Multi, the shares of Biology in NSP journals are higher, whereas the share of Medicine is lower. At the country level, 14 countries are included, among them the five BRICS countries. With respect to the NSP journals, the emphasis disciplines (in terms of world share of publications) of most countries other than USA are the disciplines in which USA has its weakest performance. The disciplinary structures of USA and of most of the other studied countries therefore tend to be different. Regarding Non-NSP_Multi and Non-Multi, the shapes of the disciplinary structures of the 14 countries can be roughly grouped into three groups, while there are more types of shapes for the countries in the NSP journals. For all five units of analysis, the discipline structures of most countries generally change only slightly between different time periods. The structures of some BRICS countries, however, change to a relatively large extent.
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| 6. |
- Jia, Yuehua, et al.
(författare)
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Efficient polymer bulk heterojunction solar cells with cesium acetate as the cathode interfacial layer
- 2013
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Ingår i: Renewable energy. - : Elsevier. - 0960-1481 .- 1879-0682. ; 50, s. 565-569
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Tidskriftsartikel (refereegranskat)abstract
- The enhanced performance of polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) blend was achieved by using cesium acetate (CH3COOCs) as cathode buffer layer. Under 100 mW/cm(2) white light illumination, the device with 0.8 nm thick CH3COOCs as cathode buffer layer exhibits power conversion efficiency (PCE) as high as (4.16 +/- 0.02) %. Compared to the control devices without cathode buffer layer and with LiF as cathode buffer layer, the PCE is enhanced similar to 100% and similar to 31%, respectively. The introduction of the CH3COOCs buffer layer effectively improves the photo-generated charge collection. The Kelvin Probe measurement shows that the work function of the CH3COOCs is estimated to be -4.0 eV, which has an ideal energy band match with PCBM and a good property for electron collection. The static contact angle results indicated that the CH3COOCs with the hydrophobic CH3COO- group has an improved wettability between the buffer layer and the hydrophobic organic active layer surface, resulting in better interfacial contact and reduced contact resistance. The improved performance may be attributed to the dissociation of semi-conducting CH3COOCs upon deposition to liberate Cs with a low work function, which reduces the interface resistance of the active layer and the cathode and enhances the interior electric field that may result in efficient charge transportation. Therefore, the CH3COOCs interlayer could be a promising alternative to LiF to improve the efficiency of the electron collection of polymer bulk heterojunction solar cells.
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| 7. |
- Lee, Chunsik, et al.
(författare)
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VEGF-B prevents excessive angiogenesis by inhibiting FGF2/FGFR1 pathway
- 2023
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Ingår i: SIGNAL TRANSDUCTION AND TARGETED THERAPY. - : SPRINGERNATURE. - 2095-9907 .- 2059-3635. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Although VEGF-B was discovered as a VEGF-A homolog a long time ago, the angiogenic effect of VEGF-B remains poorly understood with limited and diverse findings from different groups. Notwithstanding, drugs that inhibit VEGF-B together with other VEGF family members are being used to treat patients with various neovascular diseases. It is therefore critical to have a better understanding of the angiogenic effect of VEGF-B and the underlying mechanisms. Using comprehensive in vitro and in vivo methods and models, we reveal here for the first time an unexpected and surprising function of VEGF-B as an endogenous inhibitor of angiogenesis by inhibiting the FGF2/FGFR1 pathway when the latter is abundantly expressed. Mechanistically, we unveil that VEGF-B binds to FGFR1, induces FGFR1/VEGFR1 complex formation, and suppresses FGF2-induced Erk activation, and inhibits FGF2-driven angiogenesis and tumor growth. Our work uncovers a previously unrecognized novel function of VEGF-B in tethering the FGF2/FGFR1 pathway. Given the anti-angiogenic nature of VEGF-B under conditions of high FGF2/FGFR1 levels, caution is warranted when modulating VEGF-B activity to treat neovascular diseases.
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| 8. |
- Ma, Chunyu, et al.
(författare)
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Plasmon-enhanced organic solar cells with solution-processed three-dimensional Ag nanosheets
- 2013
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Ingår i: Solar Energy Materials and Solar Cells. - : ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS. - 0927-0248 .- 1879-3398. ; 109, s. 227-232
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Tidskriftsartikel (refereegranskat)abstract
- The silver nanosheets (AgNSs) prepared via normal silver mirror reaction were used to improve the performance of organic solar cells. AgNSs with a size of about 100 nm in width and 10 nm in thickness formed a 3-D network on an indium tin oxide (ITO) surface. Organic solar cells with a structure of ITO/AgNSs/poly(3,4-ethylene dioxythiophene) poly(styrenesulfonate) (PEDOT:PSS)/poly(3-hexylthiophene) and [6,6]-phenyl C-61 butyric acid methyl ester (P3HT:PC61BM)/LiF/Al exhibited an open circuit voltage (V-oc) of 0.60 +/- 0.01 V, short circuit current density (J(sc)) of 11.16 +/- 0.08 mA/cm(2), a fill factor (FF) of 53.69 +/- 0.92%, and power conversion efficiency (PCE) of 3.60 +/- 0.06%. The PCEs of organic solar cells with 3-D AgNSs layers were 1.29 times that of the control device without 3-D AgNSs layer. We attributed the improvement of the efficiency to localized surface plasmon resonance (LSPR) induced by the 3-D network of AgNSs, which enhanced the light harvest of active layers, increased the probability of exciton generation and dissociation.
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| 9. |
- Pan, Kui, et al.
(författare)
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Monolithically and Vertically Integrated LED-on-FET Device Based on a Novel GaN Epitaxial Structure
- 2023
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Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 70:12, s. 6393-6398
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Tidskriftsartikel (refereegranskat)abstract
- Optoelectronic devices, such as light-emitting diodes (LEDs), based on GaN-based semiconductor compounds are widely used for their advantages of long life, high reliability, and low energy consumption. The persistent challenge is integrating LED with transistors to achieve smaller size, lighter weight, higher speed, and more reliable optoelectronic integrated circuits. Here, we report monolithically and vertically integrated LED-on-FET devices fabricated on a novel GaN epitaxial structure. The designed device structure and fabrication process are simple. It also eliminates the extra area occupied by the transistor, and the shared n-GaN layer between the LED and FET reduces interconnect resistance and improves reliability. The measured threshold voltage (V-Th) of the LED-on-FET device is extrapolated as 3.9 V at the voltage (V-DD) of 5 V, and V-Th decreases with the increase of V-DD . More importantly, the gate voltage (V-GS) shows good performance in modulated electroluminescence (EL) intensity and switching capability of the LED. The integrated LED efficiently emits light modulation with a wavelength of 440 nm at V-DD= 9 V and V-GS=4-9 V (step = 1 V), which are necessary for devices in applications, such as displays and smart lighting. This epitaxy structure and integration scheme is promising in achieving large-scale optoelectronic integrated circuits, such as the next-generation micro-LED and nano-LED with super compact integrated drivers.
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| 10. |
- Qin, Wenjing, et al.
(författare)
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Surface states of ZnO nanoparticles effect on the performance of inverted-organic solar cells
- 2013
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Ingår i: Journal of Renewable and Sustainable Energy. - : American Institute of Physics (AIP). - 1941-7012. ; 5:5
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Tidskriftsartikel (refereegranskat)abstract
- ZnO is a promising material used as the electron transport layer in the inverted organic solar cells (IOSCs). However, the electrical or photoelectric properties of ZnO nanoparticles are governed by the surface states of the nanoparticles. Here, we demonstrate that the large number of hydroxyl (-OH) existed on the ZnO nanoparticles films have a vast impact on the performance of IOSCs with the structure of ITO/ZnO/poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C-61 butyric acid methyl ester (PCBM)/MoO3/Ag. The surface hydroxyl groups depredate active layer via elevating photocatalytic activity of the ZnO, hence deteriorate the device performance. Experimental results show that hydroxyl groups can be effectively detached from ZnO film by annealing. Hydroxyl groups detach more with increasing annealing temperature, resulting in less degradation of the active layer. Therefore, the efficiency is significantly improved due to increased photo-current density and decreased series resistance of IOSCs. The best device exhibits a power conversion efficiency of 3.05% after annealing at 150 degrees C.
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| 11. |
- Tian, Liang, et al.
(författare)
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Electroless Deposition of 4 μm High Ni/Au Bumps for 8 μm Pitch Interconnection
- 2022
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Ingår i: ACS Applied Electronic Materials. - : American Chemical Society (ACS). - 2637-6113. ; 4:10, s. 4966-4971
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Tidskriftsartikel (refereegranskat)abstract
- We propose that electroless plating is a superb approach to preparing metallic bumps with an ultrafine pitch for the integration of a micro light-emitting diode (micro-LED). Electroless plating does not suffer from lift-off-related issues, which are ubiquitous in thermal evaporation. Besides, it can result in much more uniform bumps than electroplating because the bump height is not affected by the current distribution. This study reports ultrafine pitch Ni/Au bumps fabricated by electroless nickel immersion gold (ENIG) plating. Furthermore, cheap metals iron and nickel are selected to catalyze the electroless nickel process. The results indicate that uniform and consistent Ni/Au bumps can be obtained through the iron sheet and nickel layer method. Besides, no voids and impurities are found inside the bumps, which is beneficial for the following interconnection process. Moreover, the change in Ni bump height values with the electroless plating time is also provided.
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| 12. |
- Van Doesum, Niels J., et al.
(författare)
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Social mindfulness and prosociality vary across the globe
- 2021
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 118:35
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Tidskriftsartikel (refereegranskat)abstract
- Humans are social animals, but not everyone will be mindful of others to the same extent. Individual differences have been found, but would social mindfulness also be shaped by one's location in the world? Expecting cross-national differences to exist, we examined if and how social mindfulness differs across countries. At little to no material cost, social mindfulness typically entails small acts of attention or kindness. Even though fairly common, such low-cost cooperation has received little empirical attention. Measuring social mindfulness across 31 samples from industrialized countries and regions (n = 8,354), we found considerable variation. Among selected country-level variables, greater social mindfulness was most strongly associated with countries' better general performance on environmental protection. Together, our findings contribute to the literature on prosociality by targeting the kind of everyday cooperation that is more focused on communicating benevolence than on providing material benefits.
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| 13. |
- Wang, Yaling, et al.
(författare)
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Enhanced performance and stability in polymer photovoltaic cells using lithium benzoate as cathode interfacial layer
- 2011
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Ingår i: SOLAR ENERGY MATERIALS AND SOLAR CELLS. - : Elsevier Science B.V., Amsterdam.. - 0927-0248. ; 95:4, s. 1243-1247
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Tidskriftsartikel (refereegranskat)abstract
- We report the enhanced performance and stability of polymer solar cells based on regioregular poly(3-hexylthiophene)(P3HT) and methanofullerene [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) blend using lithium benzoate (C6H5COOLi) as cathode buffer layer between the active layer and the Al cathode. The effects of the C6H5COOLi thickness on the performance of polymer solar cell are also investigated. Under 100 mW/cm(2) white light illumination, the device with 1 nm thick C6H5COOLi as cathode buffer layer exhibits power conversion efficiency (PCE) as high as 3.41 +/- 0.07% and the device stability is greatly extended. Compared to the solar cell with LiF/AI cathode, the PCE is increased ca. 9.4%. Introduction of C6H5COOLi buffer layer effectively increases the shunt resistance and improves the photo-generated charge collection. The improved performance may attribute to the dissociation of semi-conducting C6H5COOLi upon deposition to liberate Li with a low work function, which reduces the interface resistance of the active layer and the cathode and enhances the interior electric field that may result in efficient charge transportion. In addition, the C6H5COOLi layer may serve as an effective oxygen and moisture diffusion barrier for the organic solar cells. Therefore. C6H5COOLi is a promising candidate as an interlayer to improve the efficiency of electron collection and to reduce the ambience influence on the stability of polymer solar cells.
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| 14. |
- Wang, Yaling, et al.
(författare)
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Enhanced performance and stability of inverted planar perovskite solar cells by incorporating 1,6-diaminohexane dihydrochloride additive
- 2018
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Ingår i: Solar Energy Materials and Solar Cells. - : ELSEVIER SCIENCE BV. - 0927-0248 .- 1879-3398. ; 188, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- Herein, 1,6-Diaminohexane Dihydrochloride (1,6-DD) is introduced into perovskite precursors to fabricate the inverted planar perovskite solar cells. By regulating the concentration of 1,6-DD additive, the average power conversion efficiency (PCE) of perovskite solar cells is enhanced by 20%. The champion device achieves a relatively high PCE of 17% and an excellent fill factor of 80.1%. The PCE of the large-area (1 cm(2)) device also reaches to 13.68%. After exposure to the air for 16 days, the device with 1,6-DD additive still retains above 90% of the initial efficiency, exhibiting good stability. We demonstrate that a small amount of 1,6-DD affects the crystallization dynamic, yielding ideal perovskite film with enhanced crystallinity and enlarged grain size. The two terminal -NH3+ groups passivates the vacancy defects at the perovskite crystal surface, suppressing charge recombination and facilitating charge transportation effectively. Meanwhile, adjacent crystal surfaces are linked through the hexane alkyl chain of 1,6-DD molecule, which enhances the interaction between perovskite grains and anchors the microstructure of perovskite to some degree. Hydrophobic hexane alkyl chains also increase the moisture resistance of perovskite film. Thus, an easy and effective way is provided for fabricating efficient and stable perovskite solar cells.
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| 15. |
- Xie, Yuan, et al.
(författare)
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Key molecular alterations in endothelial cells in human glioblastoma uncovered through single-cell RNA sequencing
- 2021
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Ingår i: JCI Insight. - : American Society For Clinical Investigation. - 2379-3708. ; 6:15
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Tidskriftsartikel (refereegranskat)abstract
- Passage of systemically delivered pharmacological agents into the brain is largely blocked by the blood-brain-barrier (BBB), an organotypic specialization of brain endothelial cells (ECs). Tumor vessels in glioblastoma (GBM), the most common malignant brain tumor in humans, are abnormally permeable, but this phenotype is heterogeneous and may differ between the tumor's center and invasive front. Here, through single-cell RNA sequencing (scRNA-seq) of freshly isolated ECs from human glioblastoma and paired tumor peripheral tissues, we have constructed a molecular atlas of human brain ECs providing unprecedented molecular insight into the heterogeneity of the human BBB and its molecular alteration in glioblastoma. We identified 5 distinct EC phenotypes representing different states of EC activation and BBB impairment, and associated with different anatomical locations within and around the tumor. This unique data resource provides key information for designing rational therapeutic regimens and optimizing drug delivery.
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| 16. |
- Yang, Liying, et al.
(författare)
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Effect of cathode buffer layer on the stability of polymer bulk heterojunction solar cells
- 2010
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Ingår i: SOLAR ENERGY MATERIALS AND SOLAR CELLS. - : Elsevier Science B.V., Amsterdam.. - 0927-0248. ; 94:10, s. 1831-1834
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Tidskriftsartikel (refereegranskat)abstract
- The effect of cathode buffer layer on the stability of polymer solar cells with cesium carbonate (Cs2CO3) as the cathode buffer layer was investigated. Compared with traditional devices using lithium fluoride (LiF) as buffer layer, the use of the Cs2CO3 layer has enhanced not only open-circuit voltages and power conversion efficiencies of the polymer solar cells due to better contact with the cathode but also the device stability. From results of stability test, we concluded that the inserted Cs2CO3 buffer layer is working as a better shielding and scavenging protector which prevents the intruding of oxygen and humidity into the active layer, thereby improving the lifetime of unpackaged devices.
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| 17. |
- Yin, Bin, et al.
(författare)
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Solution-processed bulk heterojunction organic solar cells based on an oligothiophene derivative
- 2010
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Ingår i: Applied Physics Letters. - : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 97:2, s. 023303-
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Tidskriftsartikel (refereegranskat)abstract
- Organic bulk heterojunction (BHJ) solar cells based on a dicyanovinyl-substituted oligothiophene as a donor and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as an acceptor were fabricated and characterized. The oligothiophene derivative can absorb long wavelength photons of the solar radiation, which makes the solar cells with an optimized weight ratio of 1:1.4 have a decent short-circuit current density (12.4 mA/cm(2)) and open-circuit voltage (0.88 V) under AM 1.5G illumination with an intensity of 100 mW/cm(2). A power conversion efficiency (PCE) of 3.7% is achieved, which is among the best PCEs of solution processed small molecule BHJ solar cells.
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| 18. |
- Zhou, Qianying, et al.
(författare)
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Synthesis of gem-Difluorinated 2,3-Dihydrobenzofurans Using Freon-22 via [4 + 1] Annulation of Difluorocarbene and Antitumor Activity Evaluation
- 2024
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Ingår i: Organic Letters. - 1523-7060. ; 26:6, s. 1212-1217
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Tidskriftsartikel (refereegranskat)abstract
- As an inexpensive industrial chemical, chlorodifluoromethane (Freon-22), despite its relatively low reactivity, can serve as a practical CF2 source for the construction of gem-difluorinated ring structures. Here, we develop a protocol for the efficient assembly of valuable fluorinated 2,3-dihydrobenzofurans from the [4 + 1] annulation in good yields under basic conditions. The reliable practicability and scalability of the process have also been demonstrated by preparation at the multigram scale, late-stage modifications of pharmaceutical molecules, and potential antitumor potency.
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