Epidermal electronics are extensively explored as an important platform for future biomedical engineering. Epidermal devices are typically fabricated using high‐cost methods employing complex vacuum ...microfabrication processes, limiting their widespread potential in wearable electronics. Here, a low‐cost, solution‐based approach using electroconductive reduced graphene oxide (RGO) sheets on elastic and porous poly(dimethylsiloxane) (PDMS) thin films for multifunctional, high‐performance, graphene‐based epidermal bioelectrodes and strain sensors is presented. These devices are fabricated employing simple coatings and direct patterning without using any complicated microfabrication processes. The graphene bioelectrodes show a superior stretchability (up to 150% strain), with mechanical durability up to 5000 cycles of stretching and releasing, and low sheet resistance (1.5 kΩ per square), and the graphene strain sensors exhibit a high sensitivity (a gauge factor of 7 to 173) with a wide sensing range (up to 40% strain). Fully functional applications of dry bioelectrodes in monitoring human electrophysiological signals (i.e., electrocardiogram, electroencephalography, and electromyogram) and highly sensitive strain sensors for precise detection of large‐scale human motions are demonstrated. It is believed that our unique processing capability and multifunctional device platform based on RGO/porous PDMS will pave the way for low‐cost processing and integration of 2D materials for future wearable electronic skin.
A solution‐based approach using electroconductive reduced graphene oxide sheets on elastic and porous PDMS thin films for multifunctional, high‐performance, graphene‐based epidermal bioelectrode/strain sensors is presented. Fully functional applications of bioelectrodes in monitoring electrophysiological signals using human and strain sensors for precisely detecting large‐scale human motions are demonstrated.
The record efficiency of the state‐of‐the‐art polymer solar cells (PSCs) is rapidly increasing, due to the discovery of high‐performance photoactive donor and acceptor materials. However, strong ...questions remain as to whether such high‐efficiency PSCs can be produced by scalable processes. This paper reports a high power conversion efficiency (PCE) of 13.5% achieved with single‐junction ternary PSCs based on PTB7‐Th, PC71BM, and COi8DFIC fabricated by slot‐die coating, which shows the highest PCE ever reported in PSCs fabricated by a scalable process. To understand the origin of the high performance of the slot‐die coated device, slot‐die coated photoactive films and devices are systematically investigated. These results indicate that the good performance of the slot‐die PSCs can be due to a favorable molecule‐structure and film‐morphology change by introducing 1,8‐diiodooctane and heat treatment, which can lead to improved charge transport with reduced carrier recombination. The optimized condition is then used for the fabrication of large‐area modules and also for roll‐to‐roll fabrication. The slot‐die coated module with 30 cm2 active‐area and roll‐to‐roll produced flexible PSC has shown 8.6% and 9.6%, respectively. These efficiencies are the highest in each category and demonstrate the strong potential of the slot‐die coated ternary system for commercial applications.
A high power conversion efficiency of 13.5% achieved with single‐junction ternary polymer solar cells based on PTB7‐Th, PC71BM, and COi8DFIC is fabricated by slot‐die coating. This work extends to the fabrication of large‐area modules, and also to roll‐to‐roll fabrication, and demonstrates the strong potential of the slot‐die coated ternary system for commercial applications.
Gate-controlled amplifiable ultraviolet phototransistors have been demonstrated using AlGaN/GaN high-electron-mobility transistors (HEMTs) with very thin AlGaN barriers. In the AlGaN/GaN HEMTs, the ...dark current between the source and drain increases with increasing thickness of the AlGaN barrier from 10 to 30 nm owing to the increase in piezoelectric polarization-induced two-dimensional electron gas (2-DEG). However, the photocurrent of the AlGaN/GaN HEMT decreases with increasing thickness of the AlGaN barrier under ultraviolet exposure conditions. It can be observed that a thicker AlGaN barrier exhibits a much higher 2-DEG than the photogenerated carriers at the interface between AlGaN and GaN. In addition, regardless of the AlGaN barrier thickness, the source-drain dark current increases as the gate bias increases from - 1.0 to + 1.0 V. However, the photocurrent of the phototransistor with the 30 nm thick AlGaN barrier was not affected by the gate bias, whereas that of the phototransistor with 10 nm thick AlGaN barrier was amplified from reduction of the gate bias. From these results, we suggest that by controlling the gate bias, a thin AlGaN barrier can amplify/attenuate the photocurrent of the AlGaN/GaN HEMT-based phototransistor.
Herein, the effect of prebake temperature on the surface structure of zinc oxide (ZnO) nanowrinkle structures formed in a sol–gel growth process for UV photodetection is demonstrated. The sol–gel ...solutions are spin‐coated on glass and c‐plane sapphire substrates, and the resulting ZnO films are subjected to prebake and crystallization processes at 800 °C for an hour. In the sol–gel process, the prebake process is crucial in forming the nanowrinkle structure on the surface of the ZnO film. The maximum nanowrinkle structure of ZnO film is achieved at the prebake temperature of 150 °C. In addition to the formation of the optimized nanowrinkle structure, the UV response of the photodetector is further enhanced through the prebake temperature control. The nanowrinkle network structure significantly improves the optical absorbance and photoluminescence characteristics of the ZnO film, leading to high photocurrent, photoresponsivity, and external quantum efficiency for UV light. The results demonstrate the potential of sol–gel‐derived ZnO photodetectors with nanowrinkle network structures for UV sensing applications.
The sol–gel process is used to form ZnO films with nanowrinkle network (NWN) structures, enhancing ultraviolet (UV) photoresponse. Optimal NWN formation occurs at 150 °C during prebake. The NWN structure improvesoptical properties, resulting in high UV photocurrent, photoresponsivity, and quantum efficiency. This study highlights the potential of sol–gel‐derived ZnO photodetectors with NWN structures for UV sensing.
Perovskite solar cells (PSCs), which debuted with a lot of attention based on high efficiency, are establishing as one of the most promising thin‐film photovoltaic technologies. Currently, research ...for upscaling and commercialization through eco‐friendly solvent and process systems is being attempted. This study introduces for the first time a rheological engineering‐based locally supersaturated perovskite ink (LSPI) strategy for slot‐die process‐based PSC fabrication suitable for roll‐to‐roll continuous processes. Here, for the greenable slot‐die process, a perovskite precursor ink composed of a low‐toxic dimethyl sulfoxide (DMSO) single solvent is used and a small amount of 1,2‐dichlorobenzene (DCB) is utilized as a modulator to control the rheological properties of the ink. The addition of DCB lowers the high surface tension of the DMSO‐based perovskite precursor ink to suit the slot‐die process, enabling uniform wet film formation, and produces locally supersaturated colloids, i.e., perovskite seeds, that help growth into dense and large grains by heterogeneous nucleation with low Gibbs‐free energy. As a result, the LSPI enables slot‐die coating‐based PSCs with an efficiency of 20.61% (active areas of 0.1 cm2), which allow high efficiencies of 18.66% and 17.66% (active areas of 2.7 and 8.64 cm2) to be achieved in scale‐up to minimodules, respectively.
A strategy for highly efficient and robust perovskite solar cells via a greenable slot‐die process is reported. Locally supersaturated perovskite ink based on low‐toxic dimethyl sulfoxide is prepared by rheological engineering with a small amount of 1,2‐dichlorobenzene . The findings present a strategy for designing perovskite inks and a pathway toward the future commercialization of perovskite solar cells.
Greenhouse gas treatment is urgently needed because of the impact of climate change caused by greenhouse gas emissions after global economic growth. In this study, postcombustion capture was carried ...out to screen absorbents for simultaneous absorption and regeneration of CO2 and H2S byproducts of biogas using N-methyldiethanolamine (MDEA)-based additives. Twelve different absorbents were selected and compared according to the types of the amine group and the alcohol group. The mixture gas of 35 vol % CH4, 15 vol % CO2, and 50 ppm H2S balanced by N2 was used for absorption and regeneration. Absorption and regeneration were carried out at 35 and 80 °C, respectively. The absorbent concentration was fixed at 4.5 wt % for MDEA and 0.5 wt % for additives. In the continuous absorption and regeneration experiments, rich loading, lean loading, cyclic loading, absorption rate, and desorption rate were measured according to the loading values of CO2 and H2S using MDEA/additive mixed absorbent. CO2-rich loading was excellent in MDEA/diethylenetriamine (DETA), and CO2 cyclic capacity was excellent in MDEA/bis(3-aminopropyl)amine (APA). H2S-rich loading was superior in MDEA/APA, and H2S cyclic capacity was superior in MDEA/DETA. The CO2 absorption and regeneration rates were excellent in MDEA/piperazine (PZ), and the H2S absorption and regeneration rates were excellent in MDEA/2-amino-2-methyl-1-propanol. MDEA-based blending absorbent showed better absorption and regeneration performance than MDEA, and MDEA/PZ showed good performance for CO2 but very poor performance for H2S. It was confirmed that MDEA/APA was superior for gas composition in the simultaneous absorption and regeneration of CO2 and H2S.
Monolithic multi‐color light‐emitting diodes (LEDs) offer numerous advantages as multi‐functional lighting sources. However, the achievement of full‐color monolithic LEDs spanning from red to blue ...wavelengths is limited by the InN‐GaN material system. To overcome this limitation, this work demonstrates a new approach using hexagonal epitaxial lateral overgrowth to reduce the density of crystal defects and form micro‐surface structures. By utilizing arrowhead‐like surfaces in semipolar GaN films, indium incorporation can be controlled, leading to larger band‐filling effects and enabling full‐color red, green, and blue emissions from a single LED. Nonetheless, the red emission in monolithic full‐color LEDs is weaker than the blue emission due to the band‐filling induced blueshift that occurs with increasing current injection. To address this issue, pulse amplitude modulation and pulse width modulation modes are introduced to control the emission intensity from red to blue wavelengths. As a result, the study achieves a monolithic trichromatic white LED with color coordinates of (0.2985, 0.3948) and a color temperature of ≈6700 K by simultaneously emitting red, green, and blue LEDs with the same emission intensities. This achievement holds great promise for the development of high‐performance full‐color LEDs for multifunctional lighting sources that can span red, green, and blue wavelengths.
Monolithic multi‐color light‐emitting diodes (LEDs) face challenges in achieving full‐color from red to blue. This work investigates hexagonal epitaxial lateral overgrowth to reduce crystal defects and control indium incorporation. By introducing pulse modulation, this work achieves a trichromatic white LED with color coordinates (0.2985, 0.3948) and ≈6700 K color temperature. This advancement holds promise for high‐performance full‐color LEDs.
We investigated a flat-type p*-p LED composed of a p*-electrode with a local breakdown conductive channel (LBCC) formed in the p-type electrode region by applying reverse bias. By locally connecting ...the p*-electrode to the n-type layer via an LBCC, a flat-type LED structure is applied that can replace the n-type electrode without a mesa-etching process. Flat-type p*-p LEDs, devoid of the mesa process, demonstrate outstanding characteristics, boasting comparable light output power to conventional mesa-type n-p LEDs at the same injection current. However, they incur higher operating voltages, attributed to the smaller size of the p* region used as the n-type electrode compared to conventional n-p LEDs. Therefore, despite having comparable external quantum efficiency stemming from similar light output, flat-type p*-p LEDs exhibit diminished wall-plug efficiency (WPE) and voltage efficiency (VE) owing to elevated operating voltages. To address this, our study aimed to mitigate the series resistance of flat-type p*-p LEDs by augmenting the number of LBCCs to enhance the contact area, thereby reducing overall resistance. This structure holds promise for elevating WPE and VE by aligning the operating voltage more closely with that of mesa-type n-p LEDs. Consequently, rectifying the issue of high operating voltages in planar p*-p LEDs enables the creation of efficient LEDs devoid of crystal defects resulting from mesa-etching processes.
Flat-type InGaN-based light-emitting diodes (LEDs) without an n-type contact electrode were developed by using a local breakdown conductive channel (LBCC), and the effect of the In content of the ...InGaN quantum wells (QWs) on the local breakdown phenomenon was investigated. Electroluminescence and X-ray analyses demonstrated that the homogeneity and crystallinity of the InGaN QWs deteriorated as the In content of the InGaN QWs increased, thereby increasing the reverse leakage current and decreasing the breakdown voltage. After reverse breakdown with a reverse current of several mA, an LBCC was formed on the GaN-based LEDs. The surface size and anisotropic shape of the LBCC increased as the indium content of the InGaN QWs in the LEDs increased. Moreover, a flat-type InGaN LED without an n-type electrode was developed by using the LBCC. Notably, the resistance of the LBCC decreased with increasing indium content in the InGaN QWs, leading to lower resistance and higher light emission of the flat-type InGaN-based LEDs without an n-type contact electrode.
Potential synergism between Bruton's tyrosine kinase (BTK) inhibitor and lenalidomide in treating aggressive B-cell lymphoma has been suggested. Here, the authors report a single-arm phase II ...clinical trial of combination of acalabrutinib, lenalidomide and rituximab (R2A) in patients with aggressive relapsed/refractory aggressive (R/R) B-cell non-Hodgkin lymphoma (NHL). The primary endpoint of this study is objective response rate (ORR), and the secondary endpoints are complete remission (CR) rate, duration of response (DoR), progression-free survival (PFS) and overall survival (OS). A total of 66 patients are enrolled mostly with diffuse large B-cell lymphoma. The ORR is 54.5% and CR rate is 31.8% meeting the primary end point. The median DoR is 12.9 months, and 1-year PFS and OS rate is 33.1% and 67.5% respectively. Adverse events (AE) are manageable with the most frequent AE being neutropenia (31.8%). Patients with MYD88 mutations, subtypes known for NF-κB activation, and high BTK expression by immunohistochemistry respond well. Overall, these results show a significant efficacy of the R2A regimen in patients with aggressive R/R B-cell NHL, with exploratory biomarkers suggesting potential associations with response. (ClinicalTrials.gov 51 identifier: NCT04094142).
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