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Unraveling the Complex Nanomorphology of Ternary Organic Solar Cells with Multimodal Analytical Transmission Electron Microscopy
摘要： Elucidating the complex materials distribution in the active layers of ternary organic solar cells is one of the greatest challenges in the field of organic photovoltaics. Knowledge of the nanomorphology is key to understanding photophysical processes (e.g. charge separation, adjustment of the recombination mechanism as well as suppression of the radiationless and energetic losses) and thus improving the device performance. Here, we demonstrate for the first time the successful discrimination and spatial mapping of the active layer components of a ternary organic solar cell using analytical transmission electron microscopy. The material distribution of all three organic components was successfully visualized by multimodal imaging using complementary electron energy loss signals. A complete picture of the morphological aspects could be gained by studying the lateral and cross-sectional morphology as well as the morphology evolution as a function of the mixing ratio of the polymers. Finally, a correlation between the morphology, photophysical processes and device performance of the ternary and the reference binary system was achieved, explaining the differences of the power conversion efficiency (PCE) between the two systems.
关键词： device performance,EFTEM,morphology,TEM,Ternary organic solar cells
更新于2025-09-23 15:21:01
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Ideal alloys of two donor isomers with non-covalently conformational locking for ternary organic solar cells
摘要： Ternary organic solar cells (OSCs) based on the alloy model have great potential in maximizing the improvement of device performance due to the probability of simultaneously enhancing the photocurrent through morphology optimization and improving open circuit voltage (Voc) by energy level adjustment. However, rationally designing compatible materials and constructing an effective alloy remain difficult. In this manuscript, two donor isomers, BT-TO-ID and BT-OT-ID with non-covalently conformational locking of alkoxy groups at different position, were designed and synthesized to obtain an ‘‘ideal alloy’’. A linearly tunable Voc was observed between the Voc limitation of binary blends with the changes of the composition across the full range, indicating the behavior of an ideal alloy in the ternary blends. A face-on molecular packing and an appropriate phase separation was observed in the ternary blends due to the strong interactions between the two isomers, which facilitated charge transport and charge recombination suppression. Notable improvements of 76% and 29% in device performance were obtained for the ternary blends compared with BT-OT-ID based and BT-OT-ID based binary devices, respectively. Therefore, this work provided a probable molecular design strategy to guide the construction of an effective alloy in ternary OSCs.
关键词： Open circuit voltage,Non-covalently conformational locking,Alloy model,Device performance,Molecular packing,Phase separation,Ternary organic solar cells,Donor isomers
更新于2025-09-23 15:21:01
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Silicon as a ubiquitous contaminant in graphene derivatives with significant impact on device performance
摘要： Silicon-based impurities are ubiquitous in natural graphite. However, their role as a contaminant in exfoliated graphene and their influence on devices have been overlooked. Herein atomic resolution microscopy is used to highlight the existence of silicon-based contamination on various solution-processed graphene. We found these impurities are extremely persistent and thus utilising high purity graphite as a precursor is the only route to produce silicon-free graphene. These impurities are found to hamper the effective utilisation of graphene in whereby surface area is of paramount importance. When non-contaminated graphene is used to fabricate supercapacitor microelectrodes, a capacitance value closest to the predicted theoretical capacitance for graphene is obtained. We also demonstrate a versatile humidity sensor made from pure graphene oxide which achieves the highest sensitivity and the lowest limit of detection ever reported. Our findings constitute a vital milestone to achieve commercially viable and high performance graphene-based devices.
关键词： device performance,supercapacitors,graphene,humidity sensors,silicon contamination
更新于2025-09-23 15:21:01
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Interfacial engineering and film-forming mechanism of perovskite films revealed by synchrotron-based GIXRD at SSRF for high-performance solar cells
摘要： Organic-inorganic hybrid perovskites as promising light-harvesting materials have been the focus of scientific research and development of photovoltaics recently. Especially, metal halide perovskites currently become one of the most competitive candidates for the fabrication of solar cells with record certified efficiency over 25%. Despite the high efficiency, many fundamental questions remain unclear and need to be addressed at both the material and device levels, such as weaker stability, poorer reproducibility, easier degradation influenced by water, oxygen, thermal factors, and so on. Based on recent reports, interfacial engineering plays a crucial role in controlling the behavior of the charge carriers and in growing high quality, defect-free perovskite crystals, therefore helping to enhance device performance and operational stability. However, little attention has been paid to the interface interaction mechanism among carrier transport layers and perovskite active layer. It is extremely urgent to explore the perovskite interfaces in details and to find out how its interface structure is relative to the efficiency and hysteresis in perovskites solar cells. Based on the Shanghai Synchrotron Radiation Facility (SSRF), we have established an advanced perovskite photovoltaic device preparation and in-line test system, developed a series of unique surface diffraction analysis methods based on ex situ and in situ grazing incidence X-ray diffraction (GIXRD), and reported a large number of novel synchrotron radiation results on crystallization of the perovskite photovoltaics films. Our main investigations are aimed to deeply in-situ study the perovskite film growth dynamics using synchrotron radiation GIXRD technology in combination with a customized mini online glove box (c(H2O,O2)<1 ppm) and temperature-humidity control equipment, and so on., which should provide solid theoretical background and point to the useful direction for designing and fabricating high-performance perovskites solar cells. Moreover, a multi-functional joint characterization technology that in-situ GIXRD simultaneously combines with conventional characterization methods at synchrotron radiation beamline station must be put on the agenda in future research, which greatly promotes much more comprehensive and intuitive understanding of the nucleation, microcrystallization, and degradation mechanisms of perovskite heterojunction films, and therefore further optimizing their chemical synthesis strategies at the molecular level for functional materials.
关键词： Growth dynamics,Perovskites solar cells,Device performance,Grazing incidence X-ray diffraction,In-situ study
更新于2025-09-23 15:19:57
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Regioisomer effects of dibenzofuran-based bipolar host materials on yellow phosphorescent OLED device performance
摘要： Four regioisomers were synthesized for use as bipolar host materials for phosphorescent organic light-emitting diodes (PhOLEDs) by classic cross-coupling reactions using cyanofluorene and fused dibenzofuran and were readily purified. To realize the bipolar host material, a cyano-substituted fluorene was selected as the n-type unit and dibenzofuran as the p-type unit. Yellow PhOLEDs were fabricated with iridium(III) bis(4-phenylthieno[3,2-c]pyridinato-N,C20)acetylacetonate [PO-01] as a phosphorescent emitter. The achieved maximum current efficiency was 77.2 cd A?1 and the external quantum efficiency was 25.3% for the [PO-01]-based PhOLED; the 7-(dibenzo[b,d]furan-2-yl)-9,9-dimethyl-9H-fluorene-2-carbonitrile (CF-2-BzF) host had the best device performance. The color coordinates of yellow PhOLEDs at 1000 cd m?2 were (0.50, 0.50) (CF-1-BzF), (0.50, 0.49) (CF-2-BzF), (0.51, 0.49) (CF-3-BzF), and (0.50, 0.50) (CF-4-BzF).
关键词： regioisomer effects,phosphorescent organic light-emitting diodes,device performance,bipolar host materials,yellow PhOLEDs
更新于2025-09-23 15:19:57
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Aromatic imide/amide-based organic small-molecule emitters for organic light-emitting diodes
摘要： Organic electroluminescence materials play an important role in improving the optoelectronic performance of organic light-emitting diodes (OLEDs). Aromatic imide/amide-based organic small-molecule emitters have caught increasing attention due to their unique properties, such as strong electron-withdrawing characteristics, rigid structures and high-fluorescence quantum yields. In recent years, aromatic imide/amide semiconductors have been developed rapidly, but few reviews have been specially reported on their application in OLEDs. This study classified aromatic imides/amides into maleimide (MAI), phthalimide (PHI), naphthalimide (NAI), perylenediimide (PDI), and other imide/amide units according to the chemical structure to summarize the advances of imide/amide-based organic small-molecule emitters from the perspective of device performance and molecular design rules over the past 20 years. The luminescent mechanism was also explored. The findings of this study might provide a constructive guide towards future exploration and promote the further development of innovative imide/amide-based emitters.
关键词： Aromatic imides/amides,organic small-molecule emitters,device performance,organic light-emitting diodes,molecular design
更新于2025-09-23 15:19:57
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Order of Magnitude Improvement in Feedback Stability of Nanolasers by Inclusion of a Fano Resonance-Based Mirror
摘要： Tactile maps are efficient tools to improve spatial understanding and mobility skills of visually impaired people. Their limited adaptability can be compensated with haptic devices which display graphical information, but their assessment is frequently limited to performance-based metrics only which can hide potential spatial abilities in O&M protocols. We assess a low-tech tactile mouse able to deliver three-dimensional content considering how performance, mental workload, behavior, and anxiety status vary with task difficulty and gender in congenitally blind, late blind, and sighted subjects. Results show that task difficulty coherently modulates the efficiency and difficulty to build mental maps, regardless of visual experience. Although exhibiting attitudes that were similar and gender-independent, the females had lower performance and higher cognitive load, especially when congenitally blind. All groups showed a significant decrease in anxiety after using the device. Tactile graphics with our device seems therefore to be applicable with different visual experiences, with no negative emotional consequences of mentally demanding spatial tasks. Going beyond performance-based assessment, our methodology can help with better targeting technological solutions in orientation and mobility protocols.
关键词： cognitive load,visually impaired,haptics,Assistive device,performance,behavior,gender,visual experience
更新于2025-09-23 15:19:57
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A review of <i>β</i> -Ga <sub/>2</sub> O <sub/>3</sub> single crystal defects, their effects on device performance and their formation mechanism
摘要： As a wide-bandgap semiconductor (WBG), β-Ga2O3 is expected to be applied to power electronics and solar blind UV photodetectors. In this review, defects in β-Ga2O3 single crystals were summarized, including dislocations, voids, twin, and small defects. Their effects on device performance were discussed. Dislocations and their surrounding regions can act as paths for the leakage current of SBD in single crystals. However, not all voids lead to leakage current. There’s no strong evidence yet to show small defects affect the electrical properties. Doping impurity was definitely irrelated to the leakage current. Finally, the formation mechanism of the defects was analyzed. Most small defects were induced by mechanical damages. The screw dislocation originated from a subgrain boundary. The edge dislocation lying on a plane slightly tilted towards the (102) plane, the (101) being the possible slip plane. The voids defects like hollow nanopipes, PNPs, NSGs and line-shaped grooves may be caused by the condensation of excess oxygen vacancies, penetration of tiny bubbles or local meltback. The nucleation of twin lamellae occurred at the initial stage of “shoulder part” during the crystal growth. These results are helpful in controlling the occurrence of crystal defects and improving the device performance.
关键词： formation mechanism,crystal defects,β-Ga2O3,device performance
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Magnetic Conference (INTERMAG) - Singapore (2018.4.23-2018.4.27)] 2018 IEEE International Magnetics Conference (INTERMAG) - Scaling of all-optical switching to nanometer dimensions
摘要： The paper discusses the magnetic properties and applications of nanoscale materials, focusing on their use in optoelectronics. It presents experimental results on the manipulation of magnetic domains and the effects of external fields on material behavior. The study highlights the potential for improved device performance in magnetic storage and sensing applications.
关键词： device performance,nanotechnology,optoelectronics,magnetic materials,magnetic domains
更新于2025-09-19 17:15:36
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[IEEE 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Shenzhen, China (2019.11.25-2019.11.27)] 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Design of a multi - wavelength high irradiance LED phototherapy system for LLLT
摘要： Tactile maps are efficient tools to improve spatial understanding and mobility skills of visually impaired people. Their limited adaptability can be compensated with haptic devices which display graphical information, but their assessment is frequently limited to performance-based metrics only which can hide potential spatial abilities in O&M protocols. We assess a low-tech tactile mouse able to deliver three-dimensional content considering how performance, mental workload, behavior, and anxiety status vary with task difficulty and gender in congenitally blind, late blind, and sighted subjects. Results show that task difficulty coherently modulates the efficiency and difficulty to build mental maps, regardless of visual experience. Although exhibiting attitudes that were similar and gender-independent, the females had lower performance and higher cognitive load, especially when congenitally blind. All groups showed a significant decrease in anxiety after using the device. Tactile graphics with our device seems therefore to be applicable with different visual experiences, with no negative emotional consequences of mentally demanding spatial tasks. Going beyond performance-based assessment, our methodology can help with better targeting technological solutions in orientation and mobility protocols.
关键词： cognitive load,visually impaired,haptics,Assistive device,performance,behavior,gender,visual experience
更新于2025-09-19 17:13:59