Device Stability Research Articles

Multifaceted Design of Surface Passivator for Upgraded Charge Extraction in Perovskite Solar Cells

The nonradiative recombination arising from the interfaces of perovskite solar cells (PSCs) pose a hurdle, impacting both the efficiency and stability of devices. Functionalized organic molecules can passivate the perovskite surface to suppress the defects and can also fine‐tune the microstructure. This in turn promotes reliability and performance enhancement in solar cells. Using a design protocol, cyanoguanidine diiodide is synthesized and employed as a surface passivator for the fabrication of PSCs, and boosted performance from 20.44% to 23.04% is achieved. This improvement stems from an improved fill factor reaching up to 80.64%, together with the open‐circuit voltage (Voc) measuring 1119 mV. The steady‐state photoluminescence and microstructure of passivated perovskites display significant surface modification of the perovskite film which favorably impacts the charge carrier transfer at the interface of perovskite and Spiro‐OMeTAD. Our findings suggest that improved solar cell performance is due to the synergetic effect of amino and cyano functional groups along with the iodide reservoir in the organic passivator.

Recycling Single‐Crystal Perovskite Solar Cells With Improved Efficiency and Stability

AbstractMetal halide perovskite single crystals are promising for photovoltaic applications due to their outstanding properties. However, the high surface trap density causes severe nonradiative recombination and ion migration, hindering device performance and stability. Herein, mitigation of the deficient crystal surface is reported by optimized polishing engineering, resulting in stoichiometric lead‐iodine ratio with reduced iodide ion vacancies, increased ion migration activation energy, and suppressed nonradiative recombination. As a result, Cs0.05FA0.95PbI3 (FA = formamidinium) devices exhibit an impressive efficiency of 23.1%, which is one of the highest values for single‐crystal perovskite solar cells (PSCs). Moreover, multiple recycling of the degraded single‐crystal PSCs with higher efficiency and stability is achieved by removing the deteriorated surface, validating crystal surface dominates device degradation while the role of bulk and buried interface is negligible, which is different from polycrystalline devices. The T85 lifetime (remain 85% of initial efficiency) of Cs0.05FA0.95PbI3 devices increases to 1150 h after the recycling process, which is much better than that of previously reported single‐crystal PSCs. Since deficient crystal surface and ion migration are universal issues of perovskite materials, this work will promote the development of stable single‐crystal PSCs and other optoelectronic devices, such as X‐ray detectors, light‐emitting diodes, etc.

The Crucial Role of Organic Ligands on 2D/3D Perovskite Solar Cells: A Comprehensive Review

AbstractThe exceptional performance and potential of 2D/3D perovskites for enhancing the efficiency and stability of perovskite solar cells (PSCs) are extensively studied. However, selecting appropriate organic ligands is critical to this process. The incorporation of suitable ligands into the 2D layer can passivate surface defects, regulate energy level alignment, and significantly improve device stability. Conversely, using unsuitable ligands not only fails to achieve the desired functions, but also negatively impacts device efficiency by hindering charge carrier transport and causing energy level mismatch issues. Therefore, exploring the selection of organic ligands based on different requirements is essential. In this review, recent studies are classified based on the chemical structure of organic ligands, analyze their application requirements, and provide suggestions for choosing optimal organic ligands to construct 2D/3D perovskites. Additionally, the feasibility and necessity of utilizing more efficient organic ligands while providing guidance for future research on 2D/3D PSCs are emphasized.

Rational Tailored Polyfluorosubstituted Amide Molecule for Stabilizing PbI6 Framework and Inhibiting Ion Migration Toward Highly Efficient and Stable Perovskite Solar Cells

AbstractPerovskite solar cells (PSCs), while highly efficient, face stability challenges that hinder their commercial application. These instability issues mainly arise from the fragile nature of Pb─I bonds in perovskites, which easily break under environmental stresses such as heat and light, leading to the breakdown of the [PbI6] framework and irreversible degradation. To address these issues, a multifunctional molecule, N1,N4‐bis(2,3,5,6‐tetrafluoro‐4‐iodophenyl)terephthalamide (FIPh‐A), is designed and synthesized to enhance the stability of perovskite films and devices. FIPh‐A molecule possesses carbonyl, amino, and iodotetrafluorophenyl groups that bind and stabilize Pb2+ ions and [PbI6]4− octahedra structure, preventing ion migration in perovskite films. The activation energy of ion migration increases obviously from 0.28 eV to 0.39 eV by adding FIPh‐A verified by experiment results. The residual strain is also released efficiently by introducing FIPh‐A molecule into perovskite films characterized by grazing incidence X‐ray diffraction. The champion PSC with FIPh‐A achieves a power conversion efficiency of 24.60%. After 500 h of continuous illumination (ISOS‐L‐1) and 300 h of thermal aging at 80 °C (ISOS‐D‐2I), these PSCs with FIPh‐A maintained 93% and 77% of their initial efficiency, respectively. These results emphasize the potential of multifunctional additives in overcoming the stability challenges of PSCs, thereby facilitating their commercial advancement.

Inhibiting the zinc anodes corrosion to achieve ultra-stable high temperature aqueous zinc-ion hybrid supercapacitors

The corrosion of zinc anode significantly undermines the stability of aqueous zinc-based energy storage devices (ZnESDs), potentially leading to cell failure even explosions. In this study, we mixed a high concentration electrolyte (21 m LiTFSI) with a conventional 2 m Zn(OTF)2 electrolyte to highly reduce the activity of solvent water, which can greatly suppress the corrosion of zinc anode at room temperature and high temperatures. We systematically studied the phenomenon of ZnWiS inhibiting zinc anode corrosion at different temperatures and investigated its principle through experiments and theoretical calculations. As a result, the Zn||Zn symmetric cells demonstrated remarkable stability, sustaining over 3642 h at room temperature and over 112 h at 80 °C. Moreover, the as assembled aqueous zinc ion hybrid supercapacitors (ZHSC) also exhibited excellent cycling stability for over 5220 h at room temperature and over 165 h at 80 °C. In contrast, ZHSC assembled with 2 m Zn(OTF)2 can only cycle 80 h at room temperature, and 9 h at 80 °C. These findings confirm that reducing water activity in the electrolyte effectively contributes to achieving highly stable aqueous ZnESDs, and the universality of this strategy offering promise for its application in various aqueous metal ion energy storage devices.

A New Method for Temperature Dependent COM Parameters Extraction and Its Application to Simulation of SAW Devices

Abstract Surface Acoustic Wave (SAW) filters are widely used in mobile communication systems due to their superior performance. Yet, application scenarios for these SAW devices can be limited by temperature stability. The coupling of modes (COM) model is proved to be an efficient modeling approach to design SAW devices at present. However, temperature dependent COM parameter extraction is still absent. This work proposed a new method combining COM model with quasi-3D periodic finite element method (FEM) model coupled with thermal field, which can accurately and rapidly simulate and optimize the temperature stability of SAW devices. The COM parameters extraction method used in this study mainly depends on harmonic admittance. For a given temperature (T), the thermal effect can be computed by incorporating the linear thermal expansion coefficients and temperature coefficients of elasticity into the model. For validation, the admittance responses of a finite-length SAW resonator and the S-parameter of a double-mode SAW (DMS) for 42º YX-LiTaO3 piezoelectric substrate are calculated by using P-Matrix with the extracted COM parameters. For validation, the admittance responses of a SAW resonator on 42º YX-LiTaO3 under different temperature conditions is calculated. Furthermore, the temperature behaviors of a DMS filter on 42º YX-LiTaO3 are also analyzed based on the proposed method. Accurate predictions of the temperature behaviors for both resonator and filter were achieved and discussed. This investigation provides guidelines for design of high-performance SAW devices with good temperature stability.

Bipolar topological spin diode and topological spin transistor in finite size quantum spin Hall insulators

Abstract The miniaturization and stability of electronic devices are becoming increasingly important today. We attempt to provide the theoretical support for designing spintronic devices by numerically investigating spin transport in finite size quantum spin Hall insulators (QSHI) under a perpendicular weak magnetic field. By modifying magnetic field strength, we find the gapped spin up and spin down bands are split to realize a half-metal phase which is a promising candidate for designing an efficient spin filter. Moreover, one of the two energy gaps becomes larger and the other smaller due to the weakened or enhanced coupling between two edge states. Here we propose and demonstrate the spin filter based on a finite size QSHI junction under a magnetic field and the polarity can be inverted by a bias voltage or magnetic field. Interestingly, we find a bipolar spin diode effect that only one spin channel is opened and the other spin channel is closed at positive bias, and the opposite spin electron can be transmitted with negative bias. Two spin filters in series can be a spin transistor, the on and off states can be controlled by spin polarization of one spin filter. We show that the topological spin transistor can be controlled by the gate voltage, and it survives in moderate disorder.

The Interconnection Between the Liver and Other Organs: Insights for Hepatic Long–Term Normothermic Machine Perfusion

ABSTRACTNormothermic machine perfusion (NMP) is emerging as a promising technique for organ preservation, evaluation, and scientific research, offering the potential to enhance the viability and function of donor organs. To fully harness the benefits of NMP, sustained long–term NMP (LNMP) at 36°C for periods exceeding 24 h is required. However, the development of stable LNMP devices is hindered by our limited understanding of ex vivo liver physiology. This review synthesizes insights from clinical and experimental studies to highlight the knowledge gaps associated with the impact of the absence of various organs or systems on isolated livers during ex vivo perfusion. Additionally, it discusses liver injuries and adverse events documented in published liver LNMP studies, elucidating their underlying mechanisms. By analyzing these findings, the paper proposes a series of recommendations to establish a more stable LNMP platform, aiming to optimize the outcomes of liver preservation and expand the applications of NMP in clinical practice and research.

SPICE Simulation Assisted-Dynamic Rds(on) Characterization in 200V Commercial Schottky p-GaN HEMTs Under Unstable Phases

Abstract This paper presents a comprehensive analysis of dynamic and static RDS(ON) in Schottky p-GaN High Electron Mobility Transistors (HEMTs), highlighting the impact of off-state and hot electron trapping on device performance. The authors observed significant hysteresis in the transfer characteristics of a 200V commercial Schottky p-GaN, attributing this to charge trapping effects. A novel experimental setup, employing a multi-pulse test synchronous buck converter circuit with additional gate control and a clamping circuit, enabled precise characterization of dynamic RDS(ON) under varying conditions, including unstable phases with overcurrent. This method effectively mimics solar PV input scenarios, exposing the device to high dv/dt and di/dt stresses, which are critical for evaluating GaN device stability under transient conditions. This research also reveals that increased gate resistance reduces energy losses, challenging traditional expectations by demonstrating the nuanced gate charge dynamics of GaN HEMTs. This study overall contributes to the understanding of GaN device behavior, offering a novel approach for accurately characterizing dynamic RDS(ON) under unstable stages, furtherly advances the GaN device in complex renewable energy power converter applications.

Key features of perovskite solar cells operando stabilization with ionic liquid choline cinnamate

The ionic liquid choline cinnamate was applied for the first time as a defect passivator in light-absorbing layers of perovskite solar cells (PSCs). It was found that bulk passivation with an addition of 0.5% ionic liquid notably enhances the photothermal stability of PSCs, while surface passivation leads to the opposite effect with the loss of device stability, due to the complex origin of the influence of choline cinnamate on the defect structure and microstructure of hybrid halide perovskites.

Polymer Dielectric-Based Emerging Devices: Advancements in Memory, Field-Effect Transistor, and Nanogenerator Technologies.

Polymer dielectric materials have recently attracted attention for their versatile applications in emerging electronic devices such as memory, field-effect transistors (FETs), and triboelectric nanogenerators (TENGs). This review highlights the advances in polymer dielectric materials and their integration into these devices, emphasizing their unique electrical, mechanical, and thermal properties that enable high performance and flexibility. By exploring their roles in self-sustaining technologies (e.g., artificial intelligence (AI) and Internet of Everything (IoE)), this review emphasizes the importance of polymer dielectric materials in enabling low-power, flexible, and sustainable electronic devices. The discussion covers design strategies to improve the dielectric constant, charge trapping, and overall device stability. Specific challenges, such as optimizing electrical properties, ensuring process scalability, and enhancing environmental stability, are also addressed. In addition, the review explores the synergistic integration of memory devices, FETs, and TENGs, focusing on their potential in flexible and wearable electronics, self-powered systems, and sustainable technologies. This review provides a comprehensive overview of the current state and prospects of polymer dielectric-based devices in advanced electronic applications by examining recent research breakthroughs and identifying future opportunities.

The Role of Alkylammonium Bromides on the Surface Passivation of Stable Alcohol‐Dispersed CsPbX3 Nanocrystals and on the Stability Enhancement in Light‐Emitting Applications

AbstractThe ligand passivation is considered an attractive strategy to prepare high‐quality perovskite nanocrystals (PNCs) with improved photophysical features in polar media. However, the long‐term stabilization of PNCs in these environments is still challenging, being pivotal to understanding the protection mechanism given by prominent surface ligands and avoiding material deterioration in polar solvents. In this work, how the nature of diverse alkylammonium bromides used during surface passivation influences the photophysical properties and quality of CsPbX3 PNCs fully dispersed in alcohol environments, exhibiting stability up to 10 months are investigated. By adding didodecyldimethylammonium benzyldodecyldimethylammonium and tetrabutylammonium bromides (DDAB, BDAB, and TBAB, respectively), DDAB and BDAB promote a suitable and partial surface coverage are observed, respectively, suppressing defect sites in the nanocrystals. Conversely, TBAB shows poor surface protection, decreasing the PL features of PNCs. The presence of DDAB and BDAB favors the fabrication of color converters, and efficient light‐emitting diodes (LEDs) with external quantum efficiencies (EQE) of ≈23%. Interestingly, significant device stability with BDAB capping shows an LED half‐life of 20‐fold longer than for DDAB. This contribution offers a promising approach for preparing highly luminescent and stable alcohol‐dispersed PNCs, useful for fabricating efficient optoelectronic devices.

Efficient hole transport layers for silicon heterojunction solar cells by surface plasmonic modification in MoOx/Au NPs/MoOx stacks

This study explores the integration of Au nanoparticles (NPs) into molybdenum oxide (MoOx) thin films to form a MoOx/Au NPs/MoOx (MAM) stack. This stack serves as a hole transport layer (HTL) in silicon heterojunction solar cells, aiming to address the challenges of safety concerns and inefficient carrier transport. Ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy spectra demonstrate that the incorporation of Au NPs notably raises the work function of MAM to 5.85 eV and stabilize Mo6+ concentrations at 94.07%. In addition, Au NPs effectively act as a shield against detrimental interactions with Ag, thereby improving the interfacial stability between the back electrode and HTL. This strategic enhancement facilitates the formation of surface plasmon polaritons, reduces the contact resistance to 41.19 mΩ cm2, and boosts the quantum efficiency by injecting hot electrons and intensifying the surface electric field. These advancements lead to a significant enhancement in the fill factor and short-circuit current, leading to the development of a heterojunction solar cell with an increased efficiency (Eff) from 19.81% to 22.03%. This investigation underscores the transformative potential of engineered nanomaterials in elevating the performance and stability of photovoltaic devices, promoting the wider adoption of renewable energy technologies.

Analysis of ionic defect distribution on perovskite photodetector by temperature-dependent deep level transient spectroscopy

The High-efficiency Organohalide perovskites solar cells are produced via a solution-based method. Thus, a lot of defects are inevitable generated during fabrication processes, which are the main factors that affect the efficiency and long-term stability. The defect has been linked to the observation of reduce device stability against degradation and it can also create mid-gap states in a band structure as well act as recombination centers. Although the efficiency of the perovskite solar cells (PSCs) has been improved by curing defects using various passivation methods, deeply trapped defects in the perovskite layer have not been systematically studied, and their function is still unclear. In this study, we perform temperature-dependent deep-level transient spectroscopy (T-DLTS) measurements on PSCs, ionic defect parameters (activation energy, trap density, diffusion constants) for each observed ionic species were compared in different PSCs.

Flexible Perovskite Solar Cells: A Futuristic IoTs Powering Solar Cell Technology, Short Review.

The perovskite solar cells (PSCs) technology translated on flexible substrates is in high demand as an alternative powering solution to the Internet of Things (IOTs). An efficiency of ∼26.1% on rigid and ∼25.09% on flexible substrates has been achieved for the PSCs. Further, it is also reported that F-PSC modules have a surface area of ∼900 cm2, with a PCE of ∼16.43%. This performance is a world record for an F-PSC device more significant than ∼100 cm2. The process optimization, and use of new transport materials, interface, and compositional engineering, as well as passivation, have helped in achieving such kind of performance of F-PSCs. Hence, the review focuses mainly on the progress of F-PSCs and the low-temperature fabrication methods for perovskite films concerning their full coverage, morphological uniformity, and better crystallinity. The transmittance, band gap matching, carrier mobility, and ease of low-temperature processing are the key figures of merit of interface layers. Electrode material's flexible and transparent nature has enhanced the device's mechanical stability. Stability, flexibility, and scalable F-PSC fabrication challenges are also addressed. Finally, an outlook on F-PSC applications for their commercialization based on cost will also be discussed in detail.

High Open-Circuit Voltage Wide-Bandgap Perovskite Solar Cell with Interface Dipole Layer.

Wide-bandgap perovskite solar cells (PSCs) with high open-circuit voltage (Voc) represent a compelling and emerging technological advancement in high-performing perovskite-based tandem solar cells. Interfacial engineering is an effective strategy to enhance Voc in PSCs by tailoring the energy level alignments between the constituent layers. Herein, n-type quinoxaline-phosphine oxide-based small molecules with strong dipole moments is designed and introduce them as effective cathode interfacial layers. Their strong dipole effect leads to appropriate energy level alignment by tuning the work function of the Ag electrode to form an ohmic contact and enhance the built-in potential within the device, thereby improving charge-carrier transport and mitigating charge recombination. The organic interfacial layer-modified wide-bandgap PSCs exhibit a high Voc of 1.31V (deficit of <0.44V) and a power conversion efficiency (PCE) of 20.3%, significantly improved from the device without an interface dipole layer (Voc of 1.26V and PCE of 16.7%). Furthermore, the hydrophobic characteristics of the small molecules contribute to improved device stability, retaining 95% of the initial PCE after 500h in ambient air.

Internal flow stability analysis of vertical mixed-flow pump device based on EGT and FFT

With the purpose of researching the internal flow stability of the vertical mixed-flow pump device (VMFPD), the entire flow field was solved through the very large-eddy simulation (VLES) k- ω model and the internal flow characteristics of the pump device were quantitatively analyzed with the use of the energy gradient theory (EGT) along with the physical parameters of the flow field. The research elucidates the variety rule of the pressure along the VMFPD and the energy gradient function K as well as the time-frequency features of the pressure pulsation (PP) in the impeller and guide vane. The results demonstrate that the solid wall restriction of the guide vane and the impeller rotation cause a significant shift in the velocity and direction of the water flow. This causes a significant pressure difference between the water bodies, which makes it easier to create an unstable flow. The suction surface of the impeller blade possesses the great concentration of the area with energy gradient function K &gt; 107, which is the critical area influencing the internal flow stability of the pump device.

Enhancing the operational stability of OLED devices through the utilization of deuterated TTU host materials

Recent research on anthracene-based hydrocarbon (PNA) as the emissive layer host found that deuteration mediated the formation of these adduct species, presumably quenchers, and thus improved the device lifetime. Meanwhile, studies on deuterium in PNA host materials with stepwise deuteration are scarce. In this work, we report a systematic study of isotopic effects through independent deuteration of the phenyl or/and the dibenzofuran unit on a series of PNA materials polyaromatic dibenzofuran (PAF, PAF-d5, PAF-d7 and PAF-d12). We fabricated fluorescent OLED based on this triplet-triplet up-conversion active host materials for conventional MR-TADF emitter. A short-lived excited delayed lifetime of less than 2 μs has been observed in their electroluminescence decay studies. In addition, LT80 of up to 12.7 h has been observed in PAF-d12 at the brightness of 1000 cd m−2, corresponding to a 4-fold enhancement of OLED stability compared to the non-deuterated counterpart. We hope the current research can provide insights for further device improvement.

High-Performance Semiconducting Carbon Nanotube Transistors Using Naphthalene Diimide-Based Polymers with Biaxially Extended Conjugated Side Chains.

Polymer-wrapped single-walled carbon nanotubes (SWNTs) are a potential method for obtaining high-purity semiconducting (sc) SWNT solutions. Conjugated polymers (CPs) can selectively sort sc-SWNTs with different chiralities, and the structure of the polymer side chains influences this sorting capability. While extensive research has been conducted on modifying the physical, optical, and electrical properties of CPs through side-chain modifications, the impact of these modifications on the sorting efficiency of sc-SWNTs remains underexplored. This study investigates the introduction of various conjugated side chains into naphthalene diimide-based CPs to create a biaxially extended conjugation pattern. The CP with a branched conjugated side chain (P3) exhibits reduced aggregation, resulting in improved wrapping ability and the formation of larger bundles of high-purity sc-SWNTs. Grazing incidence X-ray diffraction analysis confirms that the potential interaction between sc-SWNTs and CPs occurs through π-π stacking. The field-effect transistor device fabricated with P3/sc-SWNTs demonstrates exceptional performance, with a significantly enhanced hole mobility of 4.72 cm2 V-1 s-1 and high endurance/bias stability. These findings suggest that biaxially extended side-chain modification is a promising strategy for improving the sorting efficiency and performance of sc-SWNTs by using CPs. This achievement can facilitate the development of more efficient and stable electronic devices.

Design of Triphenylamine-based D-π-A Systems for Efficient Ternary WORM Memory Devices.

The impact of various substituent moieties on the molecular framework of a conjugated D-A system in resistive switching memory property has been scrutinized through an array of novel D-π-A molecules. The synthesized molecules with triphenylamine (TPA) as the electron donor and dicyanovinylindanone (IC) as the electron acceptor demonstrated substantial non-volatile WORM (Write-Once Read-Many) memory behaviour with appreciable ON/OFF current ratios up to 105 and a lowest recorded threshold voltage of -0.80 V. The well-balanced combination of these potent electron donating and accepting units culminated in exceptional intramolecular charge transfer interactions and minimal band gap values (1.82-2.31 eV) for the molecules, as demonstrated by photophysical and electrochemical investigations. These factors, coupled with the thin-film morphological studies, corroborated the superior performance of the fabricated devices. A longer retention time of 2000s and an endurance of 100 cycles mark the substantial stability of the memory devices. Moreover, conversion from binary to ternary WORM memory was achieved by the effective tuning of the electronic properties of the D-A systems by various substituent moieties. Molecular simulation studies revealed that the resistive switching phenomenon arises from a synergistic interplay of charge transfer and charge trapping processes within these D-A systems.