Monolithic Device Research Articles

Realizing Bidirectional Photocurrent in Monolithic Dual‐Mode Device for Neuromorphic Vision and Logically‐Encrypted Transmission

AbstractDue to significant response contradictions, unidirectional carrier transmission of typical semiconductor p‐n junctions limits integrated sensors and artificial synapses in a monolithic device. In this work, a bipolar p‐n junction designed by employing the hydrogel/p‐GaN local contact interface with p‐GaN/(In,Ga)N heterojunction, demonstrating the bidirectional photocurrent and sensor/artificial synapse dual‐mode device successfully. After modifying Au nanoparticles, the negative (positive) photocurrent is increased by 900% (300%) under 365 nm (520 nm) light to achieve a more balanced bipolar carrier dynamic. Such a regulation of photocurrent is found to be attributed to the promotion of hydrogen evolution reaction (HER) at the hydrogel/Au/p‐GaN interface. Thus, the device achieves the ultrahigh paired‐pulse facilitation (PPF) index of 243% under self‐powered condition. Moreover, the implementation of plasticity from short‐term to long‐term demonstrates its adaptability in neural morphology visual recognition. Beyond independent working mode, the function of five classic logic gates is achieved under three‐terminal operation. Finally, an encrypted wireless communication system using dual‐channel light signals demonstrates the extensive application potential of the monolithic device. Therefore, this work presents a viable construction blueprint to meet the demands of next‐generation all‐in‐one optoelectronics for intricate application scenarios.

Compact multi-ring perfect vortex beam generator fabricated by laser direct writing

Perfect vortex beams (PVBs) have received much attention in recent years since the annular intensity distributions are independent of the topological charge (TC). However, the cost-effective preparation of micrometer-scale monolithic devices capable of generating multiple PVBs through a simple approach remains a significant challenge. In this work, a design of double-ring perfect spiral phase plates (DPSPPs) is presented for the generation of PVBs at two distinct locations along the radial direction. The respective radii and spacing of the double-ring PVBs can be tuned by changing the control parameters. The proposed DPSPPs are fabricated by the flexible femtosecond laser direct writing (FsDLW) technique. The experimentally generated double-ring vortex beams with different TCs possess an almost constant radius, which is consistent with the characteristics of PVBs. Furthermore, the double-ring PVBs with different fractional and trigonometric function TCs and the multi-ring PVB are also demonstrated. The design and fabrication methods are expected to facilitate the miniaturization of the applications of PVBs in optical manipulation, optical communication, and high-capacity information storage.

Efficient Permeable Monolithic Hybrid Tribo-Piezo-Electromagnetic Nanogenerator Based on Topological-Insulator-Composite.

Escalating energy demands of self-independent on-skin/wearable electronics impose challenges on corresponding power sources to offer greater power density, permeability, and stretchability. Here, a high-efficient breathable and stretchable monolithic hybrid triboelectric-piezoelectric-electromagnetic nanogenerator-based electronic skin (TPEG-skin) is reported via sandwiching a liquid metal mesh with two-layer topological insulator-piezoelectric polymer composite nanofibers. TPEG-skin concurrently extracts biomechanical energy (from body motions) and electromagnetic radiations (from adjacent appliances), operating as epidermal power sources and whole-body self-powered sensors. Topological insulators with conductive surface states supply notably enhanced triboelectric and piezoelectric effects, endowing TPEG-skin with a 288V output voltage (10 N, 4Hz), ∼3 times that of state-of-the-art devices. Liquid metal meshes serve as breathable electrodes and extract ambient electromagnetic pollution (±60V, ±1.6µA cm-2). TPEG-skin implements self-powered physiological and body motion monitoring and system-level human-machine interactions. This study provides compatible energy strategies for on-skin/wearable electronics with high power density, monolithic device integration, and multifunctionality.

Enhanced Buried Interface Engineering for Efficient Inverted Perovskite Solar Cells Fabricated via Vapor-Solid Reaction.

Vapor-deposited inverted perovskite solar cells utilizing self-assembled monolayer (SAM) as hole transport material have gained significant attention for their high efficiencies and compatibility with silicon/perovskite monolithic tandem devices. However, as a small molecule, the SAM layer suffers low thermal tolerance in comparison with other metal oxide or polymers, rendering poor efficiency in solar device with high-temperature (> 160°C) fabricating procedures. In this study, a dual modification approach involving AlOx and F-doped phenyltrimethylammonium bromide (F-PTABr) layers is introduced to enhance the buried interface. The AlOx dielectric layer improves the interface contact and prevents the upward diffusion of SAM molecules during the vapor-solid reaction at 170°C, while the F-PTABr layer regulates crystal growth and reduces the interfacial defects. As a result, the AlOx/F-PTABr-treated perovskite film exhibits a homogeneous, pinhole-free morphology with improved crystal quality compared to the control films. This leads to a champion power conversion efficiency of 21.53% for the inverted perovskite solar cells. Moreover, the encapsulated devices maintained 90% of the initial efficiency after 600h of ageing at 85°C in air, demonstrating promising potential for silicon/perovskite tandem application.

Lightwave-electronic harmonic frequency mixing.

Electronic frequency mixers are fundamental building blocks of electronic systems. Harmonic frequency mixing in particular enables broadband electromagnetic signal analysis across octaves of spectrum using a single local oscillator. However, conventional harmonic frequency mixers do not operate beyond hundreds of gigahertz to a few terahertz. If extended to the petahertz scale in a compact and scalable form, harmonic mixers would enable field-resolved optical signal analysis spanning octaves of spectra in a monolithic device without the need for frequency conversion using nonlinear crystals. Here, we demonstrate lightwave-electronic harmonic frequency mixing beyond 0.350 PHz using plasmonic nanoantennas. We demonstrate that the mixing process enables complete, field-resolved detection of spectral content far outside that of the local oscillator, greatly extending the range of detectable frequencies compared to conventional heterodyning techniques. Our work has important implications for applications where optical signals of interest exhibit coherent femtosecond-scale dynamics spanning multiple harmonics.

(Invited) Nanoarray Configured Monoliths for Self-Monitored Multi-Phase Reactive Processes

The incorporation of multiple functions synergistically into one device or platform can enable additions of application merits such as light weight, ease for system integration, reduced system complexity, cost-effectiveness, and programmability. This is especially true for usually complex energy, environmental, and biological systems with the integration need of many active or passive devices and components of various functionalities. In this work, we demonstrated a compact nanoarray configured monolith design with the ability to function as both a catalyst and a sensor to enable the self-monitoring of the complex multi-phase catalytic reaction processes during operation. A bimodular approach has been realized using both electrical and electrochemical interrogation modes for reactive gas and solid phase monitoring directly using the built-in catalysts. This new type of compact and built-in monolithic sensor configuration can lower the catalytic energetics and detect gas/solid composition semi-quantitatively at room temperature up to elevated temperature. Robust calibration curves of built-in sensor responses can be achieved with facile data processing and analyzing. The built-in monolith sensor shows good sensitivity and good selectivity sufficient for the self-monitoring of the reaction process. Besides, the nanoarray based monolith device has shown good environmental tolerance toward practical applications. Such compact monolithic device can serve as a self-monitored reactor, filter, and other function component that can potentially allow in-situ and real time monitoring and functional process control in complex and reactive physical and chemical environments. With further refining of the design and functional integration, this new type of smart monolithic device can provide necessary data and knowledge for future computation-driven situational awareness prediction and intelligent control of various complex dynamic processes and systems.

Monolithic Integration of Organic Solar Cell and Secondary Battery with Shared Electrode As a Photo-Rechargeable Energy Device

The solar cell-secondary battery energy system has been widely used as decentralized power generation and energy-storage system to reduce reliance on fossil fuel-based generation and mitigate fluctuations in solar cell energy supply. This typically involves power conversion by connecting two energy devices through charge controllers such as maximum power point tracker (MPPT) and pulse width modulator (PMW), which are technically mature and ensure reliable energy conversion and storage within the system. In the era of the fourth industrial revolution, characterized by the hyper-connectivity and hyper-mobility of the internet of things and wearable devices, solar-based integrated energy systems are emerging as a promising independent power source. To make devices more cost-effective, miniaturized, and energy efficient, many researchers are developing integrated energy devices that directly connect two energy devices without relying on a charge controller, a so-called "monolithic" form. However, most integrated devices reported to date still utilize a simple four-electrode structure. While this may visually resemble a monolithic device, it is functionally and structurally limited in its integration capabilities. To maximize the benefits expected from monolithic integrated devices, such as reduced process costs, miniaturization, and increased efficiency, it is essential to implement energy devices with three-electrode structures that share core components such as the electrode of the devices. In this regard, studies have been reported to realize a three-electrode energy device by utilizing the anode (or cathode) of a solar cell, which is a power generation device, as the electrode of an energy storage device, but there is a limitation that the energy density per unit area is low due to the use of a supercapacitor as the storage device, and the overall efficiency of the integrated device is low.In this study, we report on the design and implementation of a three-electrode integrated energy device sharing an electrode to improve the performance (e.g., areal capacity, energy efficiency). This integrated device uses an organic solar cell as the power generation device and a silver-zinc secondary battery as the energy storage device, and they share a silver electrode with each other. The shared silver electrode acts as a multifunctional layer that simultaneously serves as the positive electrode of the solar cell, the electrical connection between the solar cell and the secondary battery, and the cathode active material of the secondary battery. On the device perspective, by using a secondary cell instead of a capacitor, we have significantly increased the areal capacity. In order to further improve the efficiency of the integrated energy device, we applied the following three design strategies to the battery design. First, through the composition design of active ions in the electrolyte, the operating voltage of the secondary battery was matched to the same level as the maximum output voltage of the solar cell. This allows the solar cell to operate at its maximum power conversion efficiency when it charges the battery. Second, we improved the fast-charging characteristics of silver-zinc battery by ensuring that the area near the silver electrode surface is supersaturated with silver anion species during battery operation. This allows the secondary battery to accept the high-power density supplied by the solar cell at a low overvoltage, improving the efficiency of the integrated device. Finally, by applying a gel electrolyte with an optimized ratio of electrolyte components (gelling agent, hardener, salt, and plasticizer), we prevented the failure of the solar cell due to the penetration of electrolyte components and ensured the stable operation of the secondary battery. In conclusion, the aforementioned design improvements enabled the high-performance silver-zinc battery to be recharged near the maximum power point of the solar cell, achieving the highest photo conversion-storage efficiency (PSE) of any organic solar cell-based integrated energy system to date. In this presentation, the design and implementation of a solar cell-battery integrated energy device in a three-electrode configuration sharing a silver electrode will be presented in detail. In addition, secondary battery design strategies will be discussed to maximize the efficiency of the integrated device during high-power charging from solar cells.

Improvements in Long-Term Durability of CO2 Electrolyzer Producing Formate Designed for Integration with Solar Cells for Artificial Photosynthesis

Artificial photosynthetic cells have been extensively studied for carbon neutrality, yet in lab-scale. We have previously constructed practically large-sized cells consisting of CO2 electrolyzers and crystalline silicon solar cells.1,2 Our CO2 electrolyzers adopt a facing cathode-anode configuration, using a Ru complex polymer (RuCP) catalyst realizing a low overpotential for CO2 reduction and an IrO x -based catalyst with a high catalytic activity for water oxidation.3 1000 cm2-sized cells achieved a solar-to-chemical energy-conversion efficiency (η STC) of 7.2%,1 and a further scaled-up 1 m2-cell demonstrated a higher η STC of 10.5%, yielding a large formate production rate of 1.2 mol/h.2 In the present study, we improved the long-term durability of the CO2 electrolyzer. We prepared the 75 cm2-sized CO2 electrolyzer using the improved cathode and the anode, and achieved high formate Faradaic efficiencies (FE) exceeding 80% and electricity-to-chemical energy-conversion efficiencies (η ETC) of around 60% even after 3000 h operation under practical conditions, as shown in Fig. 1.In the previous large-sized cells, the operating current gradually decreased during continuous operation within dozen of hours. We investigated the causes of the degradation and identified three key factors. Two of these factors were associated with the cathode electrodes: detachment of the RuCP catalyst from the carbon supports and peeling off of the carbon supports from the conducting Ti substrates. An introduction of a pyrrole derivative containing amino group in the RuCP, coupled with an application of a UV-ozone treatment to create carboxyl groups on the carbon supports, effectively reduced the detachment of the RuCP catalyst by forming strong chemical bonds. A newly-developed chemically-resistant graphite adhesive composed of graphite particles and a polyvinylidene fluoride (PVDF) binder prevented the carbon supports from peeling off from the Ti-plates. The post-loading process of the RuCP, i.e., RuCP-loading on the carbon supports already-bonded on the Ti-plates using the new adhesive eliminated the detrimental impact of the heat treatment for curing the adhesive. The third factor involved detachment of the anode catalyst of IrO x particles from the Ti-plates.4 Therefore, we replaced the IrO x anodes with highly durable counterparts comprising IrO x -TaO x /Pt-Metal oxide/Ti-plates.Another critical issue we addressed was the validity of laboratory-based evaluations for reflecting outdoor operations. In our previous study, we vertically installed the integrated CO2 electrolyzers and solar cells on the ground and evaluated their performance under continuous simulated sunlight (ca. 1 sun).2,3 This vertical setup was chosen to prevent a decrease in η STC caused by crossover reactions that would occur when the electrolyzers are inclined. Indeed, it has been reported that oxygen reduction reaction (ORR) of the O2 bubbles generated at the anode and transferred to the cathode can be substantial in a single-chamber water-splitting reactor.5 By contrast, although the present CO2 electrolyzer was installed at an inclined angle of 30 °, which is approximately the optimal value for receiving more solar energy, the crossover reactions were well-suppressed because the porous separator film inserted between the facing cathode and anode impeded the transfer of O2 bubbles from the anode to the cathode. However, the use of a separator film raised another issue: the O2 bubbles trapped on the film narrowed the effective film area. Intermittent operation corresponding to changes in solar energy during the day mitigates the detrimental impact of the second issue.Thus, we established the groundwork for the widespread use of integrated CO2 electrolyzers and solar cells for artificial photosynthesis, demonstrating high durability, exceptional FE, and η ETC.References N. Kato, et al., A large-Sized Cell for Solar-Driven CO2 Conversion with a Solar-to-Formate Conversion Efficiency of 7.2%, Joule, (2021) 5, 687.N. Kato, et al., Solar Fuel Production from CO2 using 1 m-square-sized Reactor with a Solar-to-Formate Conversion Efficiency of 10.5%, ACS Sustain. Chem. Eng.,(2021) 9, 16031.T. Arai, S. Sato, T. Morikawa, A Monolithic Device for CO2 Photoreduction to Generate Liquid Organic Substances in a Single-Compartment Reactor, Energy Environ. Sci., (2015) 8, 1998.M. Shiozawa, et al., Improved Durability of Highly Active IrO x Electrodes for Electrocatalytic Oxygen Evolution Reaction, Electrocatalysis, (2022) 13, 830.K. Obata, et al., Multiphase Fluid Dynamics Simulations of Product Crossover in Solar-driven, Membrane-less Water Splitting, Cell Rep. Phys. Sci, (2021) 2, 100358. Figure 1

Light Conversion by Electrochemiluminescence at Semiconductor Surfaces.

ConspectusElectrochemiluminescence (ECL) is the electrochemical generation of light. It involves an interfacial charge transfer that produces the excited state of a luminophore at the electrode surface. ECL is a powerful readout method that is widely employed for immunoassays and clinical diagnostics and is progressively evolving into a microscopy technique. On the other hand, photoelectrochemistry at illuminated semiconductors is a field of research that deals with the transfer of photogenerated charge carriers at the solid-liquid interface. This concept offers several advantages such as a considerable lowering of the onset potential required for triggering an electrochemical reaction as well as light addressable chemistry, via the spatial confinement of redox reactions at locally illuminated semiconductor electrodes. The combination of ECL with photoelectrochemistry at illuminated semiconductors is termed photoinduced ECL (PECL). It deals with the triggering of an ECL reaction through the transfer of photogenerated minority charge carriers at the illuminated solid/liquid interface. PECL results in the conversion of incident photons (λexc), that are absorbed by the semiconductor photoelectrode to emitted photons (λPECL), produced by the ECL reaction. Although demonstrated in the 1970s by Bard et al. in ultradry organic solvents, PECL remained unexplored until the last five years. Nowadays, as a result of the considerable progress achieved in semiconductor photoelectrodes and ECL systems, a large variety of PECL systems can be designed by combining photoelectrode materials with ECL luminophores, making it a versatile tool for light conversion in aqueous media.In this Account, we introduce the fundamentals of ECL and photoelectrochemistry at illuminated semiconductors and review the recent developments in PECL. We discuss the two main PECL light conversion schemes: downconversion (where λexc < λPECL) and upconversion (where λexc > λPECL). Besides, PECL can be used to simplify considerably the common electrochemical setups employed for ECL. Indeed, by engineering the photoelectrode material and carefully considering the reactivity involved for ECL and its counter-reaction, PECL enables the ultimate concept of all-optical ECL (AO-ECL), i.e., ECL generation at an illuminated monolithic device immersed into the electrolyte solution. As discussed in this Account, AO-ECL is an important breakthrough that allows the simplest ECL experimental configuration ever reported, eliminating constraints such as an electrical power supply, wires, electrodes, connections, and specific electrochemical knowledge. As shown at the end of this Account, due to the robustness of recently manufactured PECL systems, several applications can already be envisioned for microscopy, elucidation of solar conversion mechanisms, near-infrared imaging, and bioanalysis.

Engineering and Design of Halide Perovskite Photoelectrochemical Cells for Solar‐Driven Water Splitting

AbstractPhotoelectrochemical cells (PEC) use solar energy to generate green hydrogen by water splitting and have an integrated device structure. Achieving high solar‐to‐hydrogen conversion (STH) efficiency along with a long operational lifetime in these cells is crucial for the production of low‐cost green hydrogen as a viable energy source. Several functional components, such as photo absorber, charge transport, and catalyst layers are interfaced in these cells to form a compact monolithic device. In this review, therefore, the engineering and design of the individual components of these cells, the interplay between them, and their interfaces are discussed in detail, as these factors determine the overall performance of the cells. The main emphasis is on halide perovskite (HP) photo absorbers, which have emerged as promising materials for use in these cells due to their superior optoelectronic properties. Recent advances in the development of efficient and stable perovskite‐based cells are highlighted and reviewed. The design of catalysts for water splitting and the effect of factors such as pH and supporting cations are also examined. Finally, the scientific challenges and future directions for designing perovskite‐based photoelectrochemical cells are discussed. This review can help researchers further advance this technology toward commercial production of green hydrogen.

Air plasma activation of catalytic sites within MXene nanosheets for oxygen evolution and urea oxidation catalysis

Atmospheric pressure medium–blocked discharge plasma modified the hydroxyl and fluorine groups on the dispersed surface of MXene as well as the valence states of metal ions to promote electrocatalytic reactions efficiently. The plasma-treated samples maintain the nature and macroscopic morphology of the open active sites of the original framework structure, whereas the valence and electronic structures of the metal centers are altered. When dielectric barrier discharge plasma-modified MXene is used to assemble a monolithic hydrolysis device for hydrogen evolution reaction (HER)||oxygen evolution reaction (OER), the current density is up to 100 mA/cm2 at 2.1 V (actual data without IR compensation). Furthermore, in urea-assisted water electrolysis HER||urea oxidation reaction, the voltage is only 1.8 V, which is 300 mV lower than that of HER||OER. Meanwhile, the electrocatalytic system can operate continuously with high durability for more than 100 h. This work provides an effective electrocatalyst not only for efficient hydrogen production but also for urea wastewater purification.

Vertically Integrated Monolithic Neuromorphic Nanowire Device for Physiological Information Processing.

This study demonstrates the conceptual design and fabrication of a vertically integrated monolithic (VIM) neuromorphic device. The device comprises an n-type SnO2 nanowire bottom channel connected by a shared gate to a p-type P3HT nanowire top channel. This architecture establishes two distinct neural pathways with different response behaviors. The device generates excitatory and inhibitory postsynaptic currents, mimicking the corelease mechanism of bilingual synapses. To enhance the signal processing efficiency, we employed a bipolar spike encoding strategy to convert fluctuating sensory signals to spike trains containing positive and negative pulses. Utilizing the neuromorphic platform for synaptic processing, physiological signals featuring bidirectional fluctuations, including electrocardiogram and breathing signals, can be classified with an accuracy of over 90%. The VIM device holds considerable promise as a solution for developing highly integrated neuromorphic hardware for healthcare and edge intelligence applications.

Photocell-Based Optofluidic Device for Clogging-Free Cell Transit Time Measurements.

Measuring the transit time of a cell forced through a bottleneck is one of the most widely used techniques for the study of cell deformability in flow. It in turn provides an accessible and rapid way of obtaining crucial information regarding cell physiology. Many techniques are currently being investigated to reliably retrieve this time, but their translation to diagnostic-oriented devices is often hampered by their complexity, lack of robustness, and the bulky external equipment required. Herein, we demonstrate the benefits of coupling microfluidics with an optical method, like photocells, to measure the transit time. We exploit the femtosecond laser irradiation followed by chemical etching (FLICE) fabrication technique to build a monolithic 3D device capable of detecting cells flowing through a 3D non-deformable constriction which is fully buried in a fused silica substrate. We validated our chip by measuring the transit times of pristine breast cancer cells (MCF-7) and MCF-7 cells treated with Latrunculin A, a drug typically used to increase their deformability. A difference in transit times can be assessed without the need for complex external instrumentation and/or demanding computational efforts. The high throughput (4000-10,000 cells/min), ease of use, and clogging-free operation of our device bring this approach much closer to real scenarios.

Monolithic silicon for high spatiotemporal translational photostimulation.

Electrode-based electrical stimulation underpins several clinical bioelectronic devices, including deep-brain stimulators1,2 and cardiac pacemakers3. However, leadless multisite stimulation is constrained by the technical difficulties and spatial-access limitations of electrode arrays. Optogenetics offers optically controlled random access with high spatiotemporal capabilities, but clinical translation poses challenges4-6. Here we show tunable spatiotemporal photostimulation of cardiac systems using a non-genetic platform based on semiconductor-enabled biomodulation interfaces. Through spatiotemporal profiling of photoelectrochemical currents, we assess the magnitude, precision, accuracy and resolution of photostimulation in four leadless silicon-based monolithic photoelectrochemical devices. We demonstrate the optoelectronic capabilities of the devices through optical overdrive pacing of cultured cardiomyocytes (CMs) targeting several regions and spatial extents, isolated rat hearts in a Langendorff apparatus, in vivo rat hearts in an ischaemia model and an in vivo mouse heart model with transthoracic optical pacing. We also perform the first, to our knowledge, optical override pacing and multisite pacing of a pig heart in vivo. Our systems are readily adaptable for minimally invasive clinical procedures using our custom endoscopic delivery device, with which we demonstrate closed-thoracic operations and endoscopic optical stimulation. Our results indicate the clinical potential of the leadless, lightweight and multisite photostimulation platform as a pacemaker in cardiac resynchronization therapy (CRT), in which lead-placement complications are common.

Flexible Monolithic Bifunctional Device Based on a Lift-off (In,Ga)N Film for Both Lighting and Self-Driven Detection.

Although flexible monolithic bifunctional devices are significant for next-generation optoelectronic devices, it is quite challenging to realize them. In this work, a flexible monolithic device with both functions of emission and self-driven detection has been proposed and demonstrated successfully. By a quick electrochemical etching method, the device is created using a lift-off (In,Ga)N film detaching from the epitaxial silicon substrate. The Si removal is beneficial for releasing stress and reducing the internal polarization effects under bending conditions, keeping the electroluminescence peak wavelength quite stable. With good flexibility, the monolithic bifunctional device can maintain both stable detection and emission performance under bending conditions. Furthermore, two functions of detection and lighting of the flexible monolithic device can not only be realized separately but also simultaneously. This means that the flexible monolithic device can detect and emit light at the same time. With the advantages of miniaturization and multifunctionality, this work paves an effective way to develop new monolithic multifunctional devices for both self-driven detection and wearable intelligent display.

Bandgap Pairing in Three‐Terminal Tandem Solar Cells: From Limiting Efficiency to Voltage‐Matched Device Performance

Three‐terminal tandem solar cells (3 T TSCs) have recently sparked increasing interest as they feature a lean monolithic device architecture similar to two‐terminal TSCs and, like four‐terminal TSCs, do not require current matching for optimal operation. In this contribution, detailed balance limit calculations for different combinations of top and bottom cell bandgaps are conducted to determine the optimum bandgap pairing and limiting efficiency of 3T TSCs. An experimental realization of a 3T TSC with perovskite and silicon sub‐cells and a combined efficiency of 28.9% is presented and used to derive a realistic parameterization for non‐radiative recombination. Herein, the optimum bandgap pairing and resulting maximum efficiency under voltage‐matched conditions for voltage‐matching ratios of 1:2 and 2:3, which is relevant for stringing and module integration of 3T TSCs, are further determined. To this end, non‐radiative recombination is incorporated in the model and quantified by matching theoretical open‐circuit voltages and those of real‐world high‐efficiency solar cells based on different absorber materials (and thus bandgaps), including the perovskite top cell of the best in‐house 3T TSC.

Reservoir Microneedle Patch Mitigates Postsurgical Atrial Fibrillation

AbstractOral amiodarone for 3–6 months is commonly required for the prevention and treatment of atrial fibrillation (AF) after surgical ablation of refractory AF. However, clinical data show that oral administration is likely to cause systemic toxicity, especially pulmonary fibrosis. Here, a new strategy is described for the treatment and prevention of postsurgical AF via the epicardial application of a monolithic reservoir microneedle device. These findings demonstrate that this strategy enables a sustained transport of amiodarone directly to the atrium, thereby maximizing therapeutic efficacy and minimizing systemic drug distribution. Notably, a significantly reduced drug dosage (only one dose of 6.3 mg for reservoir MNs versus a daily dose of ≈10 mg for oral administration) achieves therapeutic efficacy over a long period of 24 weeks in a rat AF model, circumventing the risks of pulmonary fibrosis associated with oral administration. This device can serve as a promising alternative to oral amiodarone, providing a robust therapeutic strategy for the prevention and treatment of postsurgical AF is antipicated.

Monolithic Self-Charging Storage Device with Stable 3 V Operation

Monolithic self-charging storage device with Stable 3 V Operation The energy paradigm has been changing from the traditional power plant system to micro-gride system based on renewable energy. However, renewable energy including wind, solar, and vibration, is intermittent and influenced by time, weather, and location. Thus, the suitable storage device is required for efficient utilization of renewable energy. The representative combination of renewable energy and energy storage device is an energy storage system (EES) consisting of photovoltaic systems and Lithium-ion batteries. The EES is mainly applied to social infrastructure system that generate large amounts of energy. As the Fourth Industrial Revolution progresses, the rechargeable power supply including Lithium-ion batteries is widely applied to wireless system such as sensor network, wearable device, and electric vehicles. However, the batteries have only storage function, so periodic charging is required. Thus, it is necessary to develop technologies for portable and small energy generation/storage as standalone power sources that can continuously supply power to various electronic devices. Large-scale energy production/storage system has entered the maturity stage, but the development of portable and small energy generation/storage systems based on IoT is in its early stages. To date, research on this system is conducted by simply connecting energy harvesting and energy storage device to external wires after manufacturing them independently. However, the introduction of additional wires is complicated in system design and manufacturing and has difficulty in miniaturization. These problems have motivated the integration of both functions into one device. The integrated device is fabricated by sharing one electrode, called a common electrode between the energy harvesting and storage components. Currently, research on a monolithic photo-charging storage device that integrates solar cells and energy storage devices into one device has been developed. This structure can miniaturization and flexible design, thereby it is suitable for the wearable and smart device. Although the importance of an integrated device is emphasized, the current research of monolithic device is limited to the fabrication of an integrated device without considering their practicability. In other words, most studies focus on simply connecting two devices to achieve the highest overall efficiency. In this case, since the open circuit voltage of single solar cell is under 1 V, the operation of photo-charging storage device is limited to 1 V. Thus, we proposed the monolithic photo-charging storage device operating at 3 V. We fabricated the multiple series-connected perovskite solar cell to increase the operating voltage. Since the secondary batteries are difficult to be charged by the high current density of 20 mA cm−2 solar cell owing to their storage mechanism, we choose the supercapacitor with the rapid response to an applied electric field change. We select the silver paste as the common electrode owing to its strong adhesion, high electric conductivity, and lack of chemical/mechanical damage to the solar cell and supercapacitor. Based on density functional theory (DFT) calculation, we prove the common electrode exhibits good compatibility with our supercapacitor and solar cell. For this reason, the proposed photo-charging storage device exhibits an ultra-fast charging time of less than 3 sec under AM 1.5 G illumination and high overall efficiency of 13.17 % at 1 mA cm−2 and 9.87 % at 20 mA cm−2. For electric double layer supercapacitors integrated with a solar cell, higher discharging current densities that 20 mA cm−2 have not been reported so far. We firstly demonstrate the behavior of photo-charging storage device under light/dark state by the impedance analysis. By the impedance analysis, we demonstrated that the solar cell provides a stable power supply to the supercapacitor under light condition. Further, the additional encapsulation ensures the long-term stability of photo-charging storage device and demonstrate the indoor cycling performance. We prove the photo-charging storage device has high potential as an IoT sensor power source. Figure 1

Energy Conversion and Storage in a Li Photorechargeable Battery

The development of energy systems in which solar radiation acts as an energy input is the most attractive alternative for meeting global demand in a sustainable manner in the near future. Since photovoltaic technologies are limited by the daily and seasonal intermittencies inherent in solar radiation, they often work in tandem with batteries, which can store electrical energy as electrochemical energy to be supplied on demand. However, a monolithic device that integrates electrical energy production and storage by sharing a common electrode is not yet available, a challenge since 1976 when this concept was first reported1. But, it has been in the last decade when the interest in this type of systems has increased due to advances in portable electronics and the potential in applications such as microbots or for the IoT (internet of things). In these applications, the device shape and weight factor, portability and decentralization of production and energy storage are more important properties than the overall efficiency of the process.The studies of photorechargeable batteries in the decade of 2010 were mainly based on dye-sensitized solar cells2, and extended to Li-ion batteries3. More recently, photorechargeable lithium batteries have been reported by using a semiconductor electrode with the dual functionality of light harvesting and electrochemical energy storage4, 5. However, a single material for both capacitive and light harvesting functions affects the system operation and hinders the interpretation of the physical processes because of the changes in the electrical properties of the semiconductor induced by the intercalation of ions.In a previous study, a photocapacitive system was developed based on BiVO4 light harvester and PbOx nanoparticles performing the capacitive platform by redox pesudocapacitance6. Based on this idea, a new photoelectrode based on Cu2O-TiO2 heterostructured film is studied as photoelectrode in an adapted Li coin cell (inset figure 1)7. The optical and electrochemical characterization of the electrodeposited Cu2O and nanoparticulated TiO2 films were analyzed separately by UV-vis and UPS spectroscopy and cyclic voltammetry (CV). The analysis of these results depicts an energetic scheme of the heterostructure system that explains the cyclic voltammetry registered at different light powers (figure 1). Then, a Cu2O-TiO2/Li photobattery is fabricated and its performance studied. The fabricated photorechargeable lithium battery can accumulate 88% of the theoretical energy density of the TiO2 electrode (~150 mAh g-1 at 0.1 C discharge rate) using only white LED illumination. The overall efficiency of the output electric energy respect to the light energy emitted by the LED is 0.29%. Beyond the photorechargeable lithium battery, this study analyzes the mechanism of operation in order to provide enlightening design rules to guide the development of a monolithic photorechargeable battery technology. Figure 1. Cyclic Voltammetry plots of the photorechargeable battery illuminated at different light powers (0, 50 and 100 mW/cm2) with a white LED. Inset: the adapted coin cell to allow light illumination of the photoelectrode. References G. Hodes, J. Manassen and D. Cahen, Nature, 1976, 261, 403-404. A. Hauch, A. Georg, U. O. Krašovec and B. Orel, Journal of the Electrochemical Society, 2002, 149, A1208-A1211. A. Paolella, C. Faure, G. Bertoni, S. Marras, A. Guerfi, A. Darwiche, P. Hovington, B. Commarieu, Z. Wang and M. Prato, Nature communications, 2017, 8, 14643. S. Ahmad, C. George, D. J. Beesley, J. J. Baumberg and M. De Volder, Nano letters, 2018, 18, 1856-1862. A. Kumar, P. Thakur, R. Sharma, A. B. Puthirath, P. M. Ajayan and T. N. Narayanan, Small, 2021, 17, 2105029.A. Lemsi, D. Cardenas-Morcoso, M. Haro, C. Gil-Barrachina, C. Aranda, H. Maghraoui-Meherzi, M. García-Tecedor, S. Giménez and B. Julián-López, Energy Technol., 2020, 8, 2000301.I. Ciria-Ramos, E. J. Juarez-Perez and M. Haro, Small, 2023, 2301244 Acknowledgments M.H. acknowledges the funding support from MCIN/ AEI/10.13039/501100011033 for the Ramón y Cajal fellowship (RYC2018-025222-I) and the project PID2019-108247RA-I00. E.J.J-P acknowledges the funding support from MCIN/AEI/ 10.13039/501100011033 and European Union NextGenerationEU/ PRTR (project grants PID2019-107893RB-I00 and EIN2020-112315, respectively). Figure 1

3D printed monolithic microfluidic device with an integrated porous filter: Application to pH measurement of water

Despite the available 3D printing technologies, fabrication of miniaturized analytical systems with integrated functional components is still one of the largest impediments. Here, we integrate a permeable porous filter into a 3D printed fluidic device capable of withstanding moderate hand pressure for in-field colorimetric pH measurements. The pH indicator is loaded and dried into the device, and the pH determined from converting images taken by a smartphone camera to a chromaticity diagram in International Commission on Illumination (CIE) 1931 color space and compared to calibration standards. The portable miniaturized device was fabricated with an integrated porous structure using a PolyJet 3D printer. One hundred and thirty-six devices could be printed in a single run (136 min), with cost of $0.6 per device. The 3D printed devices are capable of filtering particulate matter from the sample before mixing with an indicator avoiding optical interferences. Different environmental samples with a wide pH range (3–10) can be measured rapidly within 1 min.