- 标题
- 摘要
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- 实验方案
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In situ x-ray diffraction analysis of 2D crack patterning in thin films
摘要： In this work, the effect of the loading path on the multicracking of Nickel thin films on Kapton substrate was studied thanks to an experimental set-up combining controlled biaxial deformation, x-ray diffraction and digital image correlation. Samples were biaxially stretched up to 10% strain following either a single equibiaxial path or a complex one consisting of loading successively along each of the axes of the cruciform specimen. While the first path leads to a mud-crack pattern (random), the second leads to a roman-bricks one (square). Moreover, the in situ x-ray diffraction experiments show that the stress field developed in the thin film during the multicracking is clearly dependent on the loading path. By combining the study of stresses and x-ray diffraction peaks linewidth, we evidenced mechanical domains related to initiation of cracks and their multiplication for each loading path. Moreover, stress evolution in the thin film during mud-crack pattern formation is significantly smoother than in the case of roman-bricks one as represented in the plane stress space.
关键词： Synchrotron,Mechanical properties,Flexible substrates,Cracks
更新于2025-09-23 15:21:21
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<i>(Invited)</i> Fabrication Technique for Low-Temperature Aqueous Solution-Processed Oxide Thin-Film Transistors
摘要： Solution-processing of oxide semiconductor is a promising technique for the simple and low-cost fabrication of oxide thin-film transistors (TFTs). We demonstrate improved TFT characteristics by application of a hydrogen injection and oxidation (HIO) process to the fabrication of high-performance low-temperature oxide TFTs. The compatibility of this technique for flexible substrates was also confirmed when the HIO method was applied to solution-processed metal oxide TFTs.
关键词： solution-processing,flexible substrates,low-temperature fabrication,oxide thin-film transistors,hydrogen injection and oxidation
更新于2025-09-23 15:21:21
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Near full light absorption and full charge collection in 1-micron thick quantum dot photodetector using intercalated graphene monolayer electrodes
摘要： Quantum dots (QDs) offer several advantages in optoelectronics such as easy solution processing, strong light absorption and size tunable direct bandgap. However, their major limitation is their poor film mobility and short diffusion length (<250 nm). This has restricted the thickness of QD film to ～200–300 nm due to the restriction that the diffusion length imposes on film thickness in order to keep efficient charge collection. Such thin films result in a significant decrease in quantum efficiency for λ > 700 nm in QDs photodetector and photovoltaic devices, causing a reduced photoresponsivity and a poor absorption towards the near-infrared part of the sunlight spectrum. Herein, we demonstrate 1 μm thick QDs photodetectors with intercalated graphene charge collectors that avoid the significant drop of quantum efficiency towards λ > 700 nm observed in most QD optoelectronic devices. The 1 μm thick intercalated QD films ensure strong light absorption while keeping efficient charge extraction with a quantum efficiency of 90%–70% from λ = 600 nm to 950 nm using intercalated graphene layers as charge collectors with interspacing distance of 100 nm. We demonstrate that the effect of graphene on light absorption is minimal. We achieve a time-modulation response of <1 s. We demonstrate that this technology can be implemented on flexible PET substrates, showing 70% of the original performance after 1000 times bending test. This system provides a novel approach towards high-performance photodetection and high conversion photovoltaic efficiency with quantum dots and on flexible substrates.
关键词： Optoelectronics,Photodetectors,Quantum dots,Graphene,Flexible substrates
更新于2025-09-23 15:19:57
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Fermi velocity renormalization in graphene probed by terahertz time-domain spectroscopy
摘要： We demonstrate terahertz time-domain spectroscopy (THz-TDS) to be an accurate, rapid and scalable method to probe the interaction-induced Fermi velocity renormalization νF* of charge carriers in graphene. This allows the quantitative extraction of all electrical parameters (DC conductivity σDC, carrier density n, and carrier mobility μ) of large-scale graphene films placed on arbitrary substrates via THz-TDS. Particularly relevant are substrates with low relative permittivity (< 5) such as polymeric films, where notable renormalization effects are observed even at relatively large carrier densities (> 1012 cm-2, Fermi level > 0.1 eV). From an application point of view, the ability to rapidly and non-destructively quantify and map the electrical (σDC, n, μ) and electronic (νF*) properties of large-scale graphene on generic substrates is key to utilize this material in applications such as metrology, flexible electronics as well as to monitor graphene transfers using polymers as handling layers.
关键词： Graphene,THz-TDS,Fermi Velocity Renormalization,Mobility Mapping,Flexible Substrates
更新于2025-09-23 15:19:57
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Flexible high-efficiency CZTSSe solar cells on diverse flexible substrates via an adhesive-bonding transfer method
摘要： Cu2ZnSn(S,Se)4 (CZTSSe) thin-film solar cells are showing great promise due to using earth-abundant and non-toxic materials and tuning the bandgap through the amount of S and Se. Flexible high-efficiency CZTSSe solar cells are one of the outstanding research challenges because they currently require the use of thick glass substrates due to the high-temperature heat treatment process, and for this reason, few flexible CZTSSe solar cells have been reported. Furthermore, most researchers have used thin glass and metal substrates with little flexibility; the power conversion efficiency (PCE or ?) values of the solar cells made with them have been somewhat lower. To overcome these hurdles, we transferred high-efficiency CZTSSe solar cells formed on a soda-lime glass substrate to flexible substrates via an adhesive-bonding transfer method. Via this method, we were able to achieve the PCE of 5.8 to 7.1% on completely flexible substrates such as cloth, paper, and polyethylene terephthalate (PET). In particular, we were able to produce a CZTSSe solar cell on a PET substrate with a PCE of 7.1%, which is the highest among fully-flexible CZTSSe solar cells currently known to us. In addition, we deeply analyzed the PCE degradation of the flexible CZTSSe solar cell fabricated by the transfer method through a panoramic focused ion-beam image and nanoindentation. From the results of our work, we provide an insight into the possibility of making flexible high-efficiency CZTSSe solar cells using our transfer method.
关键词： thin-film solar cell,transfer method,polyethylene terephthalate (PET),Cu2ZnSn(S,Se)4 (CZTSSe),diverse flexible substrates
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Evaluating the Electricity Production and Energy Saving from Transparent Photovoltaics for Windows in Commercial Buildings
摘要： A pentacene (C22H14)-based high-voltage organic thin-film transistor (HVOTFT) was demonstrated on both a rigid and a flexible substrate. The HVOTFT showed minimal degradation of the current–voltage (I–V ) characteristics under flexure. Consistent with the previous reports on amorphous silicon (a-Si) TFTs, the offset drain/source structure enabled high-voltage operation, allowing for the HVOTFT to switch very large drain-to-source voltages (VDS > 300 V) with a relatively lower controlling voltage (0 V < VG < 20 V). The HVOTFT was evaluated with three different gate insulators to assess how the dielectric constant and interface states influence device performance. Due to the high electric field generated in the device, the HVOTFT suffered from impeded charge injection into the gated semiconductor channel, similar to that reported in a-Si-based high-voltage TFTs, as well as from a nonsaturating I–V characteristic behavior similar to the short-channel effects found in FETs. A field plate was implemented to improve charge injection into the gated semiconductor channel. Output characteristics of the HVOTFT were numerically corrected to demonstrate that the device I–V can be modeled with the existing Si-based FET models.
关键词： Flexible substrates,high-κ gate dielectrics,organic thin-film transistors (HVTFTs),high-voltage semiconductors
更新于2025-09-19 17:13:59
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Mechanism of Current Shunting in Flexible Cu <sub/>2</sub> Zn <sub/> 1? <i>x</i> </sub> Cd <sub/><i>x</i> </sub> Sn(S,Se) <sub/>4</sub> Solar Cells
摘要： Partial cation substitution is an effective way to inhibit defects and carrier recombination, which can improve the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. Herein, flexible Cu2Zn1?xCdxSn(S,Se)4 (x = 0–15%) solar cells are fabricated on Mo foils with partial Cd substitution for Zn via a green solution-process. The best device performance can be achieved when Cd/(Zn + Cd) = 8%, with an efficiency up to 6.49% and a significantly improved device repeatability. The EU decreases from 24 to 15 meV, indicating that antisite defects and band tailings are effectively suppressed. C–V data reveal that Wd and Vbi are enhanced after doping Cd, resulting in a stronger built-in electric field which facilitates Fermi-level splitting and hence increases band bending of the absorber toward the junction interface. Furthermore, the mechanism of current shunting is studied using an equivalent circuit model with three parallel current pathways to fit J–V curves. The key parameters for the solar cell diode such as A, J0, and Rsh are significantly improved by partially substituting Zn with Cd, demonstrating that current shunting loss is suppressed and the junction quality is improved, resulting in a significant improvement in device repeatability.
关键词： current shunting,Cu2ZnSn(S,Se)4 solar cells,Cd substitutions,Mo foils,flexible substrates
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Is Damp Heat Degradation of c-Si Modules Essentially Universal?
摘要： A pentacene (C22H14)-based high-voltage organic thin-film transistor (HVOTFT) was demonstrated on both a rigid and a flexible substrate. The HVOTFT showed minimal degradation of the current–voltage (I–V ) characteristics under flexure. Consistent with the previous reports on amorphous silicon (a-Si) TFTs, the offset drain/source structure enabled high-voltage operation, allowing for the HVOTFT to switch very large drain-to-source voltages (VDS > 300 V) with a relatively lower controlling voltage (0 V < VG < 20 V). The HVOTFT was evaluated with three different gate insulators to assess how the dielectric constant and interface states influence device performance. Due to the high electric field generated in the device, the HVOTFT suffered from impeded charge injection into the gated semiconductor channel, similar to that reported in a-Si-based high-voltage TFTs, as well as from a nonsaturating I–V characteristic behavior similar to the short-channel effects found in FETs. A field plate was implemented to improve charge injection into the gated semiconductor channel. Output characteristics of the HVOTFT were numerically corrected to demonstrate that the device I–V can be modeled with the existing Si-based FET models.
关键词： Flexible substrates,high-κ gate dielectrics,organic thin-film transistors (HVTFTs),high-voltage semiconductors
更新于2025-09-16 10:30:52
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A linear D–π–A based hole transport material for high performance rigid and flexible planar organic–inorganic hybrid perovskite solar cells
摘要： A facile and less expensive hole transport material is essential to enhance the power conversion efficiency (PCE) of perovskite solar cells (PSC) without compromising the ambient stability. Here, we designed and synthesized a new class of HTM by introducing donor–π–acceptor (D–π–A). The HTM was synthesized by combining the moieties of triphenylamine, biphenyl and oxadiazole derivatives as electron donating, π-spacer and electron withdrawing moieties, respectively, named 4′-(5-(4-(hexyloxy)phenyl)-1,3,4-oxadiazol-2-yl)-N,N-bis(4-methoxyphenyl)-[1,1′:4′,1′′:4′′,1′′′-quaterphenyl]-4-amine (TPA-BP-OXD). The π–π conjugation is increased by introducing the biphenyl π-spacer. The HTM was terminated with an OXD-based moiety and framed as a D–π–A-based HTM that trigged improvement in the charge transportation properties due to its π–π interactions. We rationally investigated the HTM by characterizing its photophysical, thermal, electrochemical, and charge transport properties. The great features of the HTM stimulated us to explore it on rigid and flexible substrates as a dopant-free HTM in planar inverted-perovskite solar cells (i-PSCs). The device performance in solution processed dopant-free HTM based i-PSC devices on both rigid and flexible substrates showed PCEs of 15.46% and 12.90%, respectively. The hysteresis is negligible, which is one of the most effective results based on a TPA-BP-OXD HTM in planar i-PSCs. The device performance and stability based on the TPA-BP-OXD HTM are better due to higher extraction and transportation of holes from the perovskite material, reduced charge recombination at the interface, and enhanced hydrophobicity of the HTM to compete for a role in enhancing the stability. Overall, our findings demonstrate the potentiality of the TPA-BP-OXD based HTM in planar i-PSCs.
关键词： perovskite solar cells,hole transport material,donor–π–acceptor,power conversion efficiency,flexible substrates
更新于2025-09-12 10:27:22
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Acetonitrile based single step slot-die compatible perovskite ink for flexible photovoltaics
摘要： The demonstration of photovoltaic devices with high power conversion efficiencies using low cost perovskite materials hints at the possibility of dramatically lowering the cost of solar energy. Key to further exploiting the potential of these materials is developing rapid processing techniques that can be used to deliver lower cost high throughput manufacture. This work details the development of low-viscosity rapid drying perovskite formulations designed to give high quality solar films when slot-die coated on flexible roll-to-roll compatible substrates. A single step slot-die compatible perovskite ink based on an acetonitrile/methylamine solvent system utilizing a chloride additive is developed, resulting in large area perovskite films from slot-die coating under ambient conditions. The drying conditions for the perovskite film are optimized and fast (<10 min), low temperature (<120 °C) drying of slot-die coated films on flexible substrates are demonstrated and result in high performance devices.
关键词： acetonitrile,chloride additive,flexible substrates,methylamine,photovoltaics,perovskite,slot-die coating
更新于2025-09-12 10:27:22