Achieving an Ultralow-κ yet Strong and Transparent Film by Antisolvent-Confined Nanowelding of Electrospun Polyimide Nanofibers.

Developing ultralow-κ (dielectric constant) polyimides (PIs) that are mechanically robust while also being optically transparent is challenging. For the first time, we report a nanoporous PI film with an ultralow κ of 1.8 in combination with a tensile strength of up to 180 MPa, a Young's modulus of up to 6 GPa, and a transmittance of ∼88%. This is achieved by direct nanowelding of a porous electrospun PI nanofiber membrane using a simple mixture of ethanol-dominating DMAc. Benefiting from the effective evaporation of the antisolvent ethanol upon heating, the proposed nanowelding approach allows for the localized surface dissolution of the PI nanofibers, which enables the dissolved PI to "glue" the nanofibers and occupy vacant space in the membrane, resulting in the formation of a dense but nanoporous self-reinforced nanocomposite film. Our findings provide a renewed understanding of the potential of electrospun nanofibrous materials, and the underlying principle can hopefully be applied to other commodity polymers.

Scalable Preparation of Polyimide Sandwiched Separator for Durable High-Rate Lithium-Metal Battery.

The ever-growing demands for efficient energy storage accelerate the development of high-rate lithium-metal battery (LMB) with desirable energy density, power density, and cycling stability. Nevertheless, the practical application of LMB is critically impeded by internal temperature rise and lithium dendrite growth, especially at high charge/discharge rates. It is highly desired but remains challenging to develop high-performance thermotolerant separators that can provide favorable channels to enable fast Li+ transport for high-rate operation and simultaneously homogenize the lithium deposition for dendrite inhibition. Polyimide-based separators with superior thermal properties are promising candidate alternatives to the commercial polyolefin-based separators, but previous strategies of designing either nanoporous or microporous channels in polyimide-based separators often meet a dilemma. Here, a facile and scalable approach is reported to develop a polyimide fiber/aerogel (denoted as PIFA) separator with the microporous polyimide fiber membrane sandwiched between two nanoporous polyimide aerogel layers, which can enable LMBs with remarkable capacity retention of 97.2% after 1500 cycles at 10 C. The experimental and theoretical studies unravel that the sandwiched structure of PIFA can appreciably enhance the electrolyte adsorption and ionic conductivity; while, the aerogel coating can effectively inhibit dendrite growth to realize durable high-rate LMBs.

Enhancing the Efficiency of Flexible, Large-Area, ITO-Free Organic Photovoltaic Devices.

The development of flexible ITO-free devices is crucial for the industrial advancement of organic photovoltaic (OPV) technology. Here, a novel ITO-free device architecture is proposed, and ITO-free OPV devices are realized on glass substrates with performance comparable to that of ITO-based devices. It is also demonstrated that the performance of ITO-free devices on polyethylene terephthalate (PET) substrates is limited due to the higher surface roughness of PET, leading to high voltage losses, low device quantum efficiency, and high device leakage current. To address the issue of high roughness on the PET surface, a polyimide (PI) modification strategy is developed and the PI-modified PET is employed as the substrate to construct flexible ITO-free OPV devices and large-area modules with an active area of up to 16.5 cm2. This approach leads to decreased trap-assisted recombination losses, enhanced exciton dissociation efficiency, and a reduced density of pinholes in flexible OPV devices, resulting in improved photovoltaic performance under both strong and weak illumination conditions. The outcomes of this work are expected to advance the industrial development of flexible organic photovoltaic technology.

Hierarchical Polyimide Microparticles with Controllable Morphology.

Hierarchical polyimides (PIs) not only show outstanding thermal stability and high mechanical strength but also have great advantages in terms of microstructure and surface area, which makes them highly valuable in various fields such as aerospace, microelectronics, adsorption, catalysis, and energy storage. However, great challenges still remain in the synthesis of hierarchical PIs with well-defined microstructure. Herein, polyamide acid salts (PAAS) with tunable ionization degree are synthesized first via the polymerization of dianhydride and diamine monomers in deionized water with 1,2-dimethylimidazole (DMIZ). Then cationic cetyltrimethylammonium chloride (CTAC) is added to the PAAS aqueous solution to induce the formation of polyelectrolyte-surfactant complexes based on electrostatic interaction. After a typical hydrothermal reaction (HTR) procedure, hierarchical PIs with different microstructures such as urchin-like PI microparticles, flower-like PI microparticles, and lamellar PI petals can be fabricated simply by changing the additive amount of DMIZ and CTAC. The nanostructure self-assemblies of PAAS are dominated by the charges on macromolecular chains and the formation of hierarchical structures of polymers is ascribed to a geometrical selection process during crystal growth. This work provides valuable insights into the self-assembly behaviors of polyelectrolyte systems for synthesizing well-defined hierarchical polymers.

Superspreading-Based Fabrication of Thermostable Nanoporous Polyimide Membranes for High Safety Separators of Lithium-Ion Batteries.

The development of thermally stable separators is a promising approach to address the safety issues of lithium-ion batteries (LIBs) owing to the serious shrinkage of commercial polyolefin separators at elevated temperatures. However, achieving controlled nanopores with a uniform size distribution in thermostable polymeric separators and high electrochemical performance is still a great challenge. In this study, nanoporous polyimide (PI) membranes with excellent thermal stability as high-safety separators is developed for LIBs using a superspreading strategy. The superspreading of polyamic acid solutions enables the generation of thin and uniform liquid layers, facilitating the formation of thin PI membranes with controllable and uniform nanopores with narrow size distribution ranging from 121 ± 5 nm to 86 ± 6 nm. Such nanoporous PI membranes display excellent structural stability at elevated temperatures up to 300 °C for at least 1 h. LIBs assembled with nanoporous PI membranes as separators show high specific capacity and Coulombic efficiency and can work normally after transient treatment at a high temperature (150 °C for 20 min) and high ambient temperature, indicating their promising application as high-safety separators for rechargeable batteries.

Enhancing Zinc Electrode Stability Through Pre-Desolvation and Accelerated Charge Transfer via a Polyimide Interface for Zinc-Ion Batteries.

Aqueous zinc-based energy storage devices possess superior safety, cost-effectiveness, and high energy density; however, dendritic growth and side reactions on the zinc electrode curtail their widespread applications. In this study, these issues are mitigated by introducing a polyimide (PI) nanofabric interfacial layer onto the zinc substrate. Simulations reveal that the PI nanofabric promotes a pre-desolvation process, effectively desolvating hydrated zinc ions from Zn(H2O)6 2+ to Zn(H2O)4 2+ before approaching the zinc surface. The exposed zinc ion in Zn(H2O)4 2+ provides an accelerated charge transfer process and reduces the activation energy for zinc deposition from 40 to 21 kJ mol-1. The PI nanofabric also acts as a protective barrier, reducing side reactions at the electrode. As a result, the PI-Zn symmetric cell exhibits remarkable cycling stability over 1200 h, maintaining a dendrite-free morphology and minimal byproduct formation. Moreover, the cell exhibits high stability and low voltage hysteresis even under high current densities (20 mA cm-2, 10 mAh cm-2) thanks to the 3D porous structure of PI nanofabric. When integrated into full cells, the PI-Zn||AC hybrid zinc-ion capacitor and PI-Zn||MnVOH@SWCNT zinc-ion battery achieve impressive lifespans of 15000 and 600 cycles with outstanding capacitance retention. This approach paves a novel avenue for high-performance zinc metal electrodes.

Double-Phase-Networking Polyimide Hybrid Aerogel with Exceptional Dimensional Stability for Superior Thermal Protection System.

Polyimide aerogels have been extensively used in thermal protection domain because they possess a combination of intrinsic characteristics of aerogels and unique features of polyimide. However, polyimide aerogels still suffer significant thermally induced shrinkage at temperatures above 200 °C, restricting their application at high temperature. Here, a novel "double-phase-networking" strategy is proposed for fabricating a lightweight and mechanically robust polyimide hybrid aerogel by forming silica-zirconia-phase networking skeletons, which possess exceptional dimensional stability in high-temperature environments and superior thermal insulation. The rational mechanism responsible for the formation of double-phase-networking aerogel is further explained, generally attributing to chemical crosslinking reactions and supramolecular hydrogen bond interactions derived from the main chains of polyimide and silane/zirconia precursor/sol. The as-prepared aerogels exhibit excellent high-temperature (270 °C) dimensional stability (5.09% ± 0.16%), anti-thermal-shock properties, and low thermal conductivity. Moreover, the hydrophobic treatment provides aerogels high water resistance with water contact angle of 136.9°, further suggestive of low moisture content of 3.6% after exposure to 70 °C and 85% relative humidity for 64 h. The proposed solution for significantly enhancing high-temperature dimensional stability and thermal insulation provides a great supporting foundation for fabricating high-performance organic aerogels as thermal protection materials in aerospace.

p/n-Type Polyimide Covalent Organic Frameworks for High-Performance Cathodes in Sodium-Ion Batteries.

Covalent organic frameworks (COFs) are viewed as promising organic electrode materials for metal-ion batteries due to their structural diversity and tailoring capabilities. In this work, firstly using the monomers N,N,N',N'-tetrakis(4-aminophenyl)-1,4-phenylenediamine (TPDA) and terephthaldehyde (TA), p-type phenylenediamine-based imine-linked TPDA-TA-COF is synthesized. To construct a bipolar redox-active, porous and highly crystalline polyimide-linked COF, i.e., TPDA-NDI-COF, n-type 1,4,5,8-naphthalene tetracarboxylic dianhydride (NDA) molecules are incorporated into p-type TPDA-TA-COF structure via postsynthetic linker exchange method. This tailored COF demonstrated a wide potential window (1.03.6 V vs Na+/Na) with dual redox-active centers, positioning it as a favorable cathode material for sodium-ion batteries (SIBs). Owing to the inheritance of multiple redox functionalities, TPDA-NDI-COF can deliver a specific capacity of 67 mAh g-1 at 0.05 A g-1, which is double the capacity of TPDA-TA-COF (28 mAh g-1). The incorporation of carbon nanotube (CNT) into the TPDA-NDI-COF matrix resulted in an enhancement of specific capacity to 120 mAh g-1 at 0.02 A g-1. TPDA-NDI-50%CNT demonstrated robust cyclic stability and retained a capacity of 92 mAh g-1 even after 10 000 cycles at 1.0 A g-1. Furthermore, the COF cathode exhibited an average discharge voltage of 2.1 V, surpassing the performance of most reported COF as a host material.

Defect-Engineered Metal-Organic Framework/Polyimide Mixed Matrix Membrane for CO2 Separation.

Defect-engineered metal-organic frameworks (MOFs) with outstanding structural and chemical features have become excellent candidates for specific separation applications. The introduction of structural defects in MOFs as an efficient approach to manipulate their functionality provides excellent opportunities for the preparation of MOF-based mixed matrix membranes (MMMs). However, the use of this strategy to adjust the properties and develop the separation performance of gas separation membranes is still in its early stages. Here, a novel defect-engineered MOF (quasi ZrFum or Q-ZrFum) was synthesized via a controlled thermal deligandation process and incorporated into a CO2-philic 6FDA-durene polyimide (PI) matrix to form Q-ZrFum loaded MMMs. Defect-engineered MOFs and fabricated MMMs were investigated regarding their characteristic properties and separation performance. The incorporation of defects into the MOF structure increases the pore size and provides unsaturated active metal sites that positively affect CO2 molecule transport. The interfacial compatibility between the Q-ZrFum particles and the PI matrix increases via the deligandation process, which improves the mechanical strength of Q-ZrFum loaded membranes. MMM containing 5 wt.% of defect-engineered Q-ZrFum exhibits excellent CO2 permeability of 1308 Barrer, which increased by 99 % compared to the pure PI membrane (656 Barrer) at a feed pressure of 2 bar. CO2/CH4 and CO2/N2 selectivity reached 44 and 26.6 which increased by about 70 and 16 %, respectively. This study emphasizes that defect-engineered MOFs can be promising candidates for use as fillers in the preparation of MMMs for the future development of membrane-based gas separation applications.

Silane modified Cr2O3/polyimide nanocomposite films with excellent surface insulation performance for space applications.

The exploration of deep space significantly increases the probability of spacecraft failures due to surface electrostatic discharge, which imposes higher vacuum insulation protection requirements on polyimide (PI), the external insulation material of spacecrafts. To address this challenge, this study proposes using silane coupling agent KH550 for organic grafting treatment of Cr2O3nanoparticles, which are then used to dope and modify PI to enhance the vacuum surface insulation of PI films. The KH550 grafting improves the interface strength between the fillers and the matrix, allowing the fillers to be uniformly dispersed in the matrix. Compared to pure PI films, the prepared PI-Cr2O3@KH550 composite films exhibit significantly enhanced vacuum surface flashover voltage, improved surface/volume resistivity, and dielectric properties. The results demonstrate that PI composite films with 0.8% by mass of Cr2O3@KH550 show the most notable performance improvement, with the DC flashover voltage and impulse flashover voltage in vacuum increasing by 20.7% and 27.8%, respectively. The doping of chromium oxide nanoparticles introduces more deep traps into the PI films and reduce the surface resistivity. The higher deep trap density inhibits charge migration, thereby alleviating secondary electron emission and surface electric field distortion. Simultaneously, the lower surface resistivity facilitates dissipating surface charges and improves the surface insulation. These findings are of significant reference value for promoting the enhancement of aerospace insulation performance.

Synthesis of silicon carbide in a matrix of graphite-like carbon prepared via carbonization of rigid-rod polyimide Langmuir-Blodgett films on silicon substrate.

Silicon carbide (SiC) is a wide-band gap semiconductor that exceeds other semiconducting materials (except diamond) in electrical, mechanical, chemical, and radiation stability. In this paper, we report a novel approach to fabrication of SiC nano films on a Si substrate, which is based on the endotaxial growth of a SiC crystalline phase in a graphite-like carbon (GLC) matrix. GLC films were formed by carbonization of rigid rod polyimide (PI) Langmuir-Blodgett (LB) films on a Si substrate at 1000 °C in vacuum. After rapid thermal annealing of GLC films at 1100 °C and 1200 °C, new types of heterostructures SiC(10 nm)/GLC(20 nm)/Si(111) and SiC(20 nm)/GLC(15 nm)/SiC(10 nm)/Si(111) were obtained. The SiC top layer was formed due to the Si-containing gas phase present above the surface of GLC film. An advantage of the proposed method of endotaxy is that the SiC crystalline phase is formed within the volume of the GLC film of a thickness predetermined by using PI LB films with different numbers of monolayers for carbonization. This approach allows growing SiC layers close to the 2D state, which is promising for optoelectronics, photovoltaics, spintronics.

Rational construction of dicarbonous CB/CNT@PI composites toward low filler loading and low-frequency electromagnetic wave absorption.

With the application of low frequency radar and the demand for stealth of high temperature resistant components, it is increasingly urgent to develop absorbing materials with both low frequency and high temperature resistant properties. Here, we successfully prepared various carbon/polyimide composites as low-frequency electromagnetic wave (EMW) absorbing materials by simple blending method. The well-designed mesh lap structure introduces a large amount of free space, further optimizing the impedance matching of the material. At the same time, the multiple loss mechanism formed by the combination of carbon black dominated polarization and carbon nanotube dominated conductive loss enhances the loss of incident EMW. The results showed that only 10 wt% filler loading of the CB/CNT@PI is achieved in the low frequency range (1-4 GHz) with a minimum reflection loss strength of -18.3 dB, which has obvious advantages compared with other works in recent years. This study provides a way for the design and preparation of resin-based absorbing materials.

Activation of polyimide by oxygen plasma for atomic layer deposition of highly compact titanium oxide coating.

Titanium oxide (TiO2) coated polyimide has broad application prospects under extreme conditions. In order to obtain a high-quality ultra-thin TiO2coating on polyimide by atomic layer deposition (ALD), the polyimide was activated byin situoxygen plasma. It was found that a large number of polar oxygen functional groups, such as carboxyl, were generated on the surface of the activated polyimide, which can significantly promote the preparation of TiO2coating by ALD. The nucleation and growth of TiO2were studied by x-ray photoelectron spectroscopy monitoring and scanning electron microscopy observation. On the polyimide activated by oxygen plasma, the size of TiO2nuclei decreased and the quantity of TiO2nuclei increased, resulting in the growth of a highly uniform and dense TiO2coating. This coating exhibited excellent resistance to atomic oxygen. When exposed to 3.5 × 1021atom cm-2atomic oxygen flux, the erosion yield of the polyimide coated with 100 ALD cycles of TiO2was as low as 3.0 × 10-25cm3/atom, which is one order less than that of the standard POLYIMIDE-ref Kapton®film.

Sulfonated Polyimide Membranes Constructed by Main-Chain and Molecular-Network Engineering Strategy for Direct Methanol Fuel Cell.

Excessive swelling is one important factor that leads to high fuel permeability and limited operating concentration of methanol for proton exchange membranes. Herein, a collaborative strategy of main-chain and molecular-network engineering is applied to lower swelling ratio and improve methanol resistance for highly sulfonated polyimide. Two m-phenylenediamine monomers (4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene-1,3-diamine and 4,6-bis(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene-1,3-diamine) with tetrafluorostyrol groups are designed and synthesized. Two series of cross-linked sulfonated polyimides (CSPI-Ts, CSPI-Bs) are prepared from the two diamines, 4,4'-diaminostilbene-2,2'-disulfonic acid and 1,4,5,8-naphthalenetetracarboxylicdianhydride. The rigid main-chain structure is cornerstone for wet CSPI-Ts and CSPI-Bs remaining stable at elevated temperatures. The introduction of hydrophobic cross-linked network further improves their dimensional stability and methanol resistance. CSPI-Ts and CSPI-Bs show obviously improved performances containing high proton conductivity (121 ± 0.27-158 ± 0.35 S cm-1 ), low swelling ratio (9.6 ± 0.40%-16.1 ± 0.01%) and methanol permeability (4.14-7.69 × 10-7 cm2 s-1 ) at 80 °C. The direct methanol fuel cell (DMFC) is assembled from CSPI-T-10 with balanced properties, and it exhibits high maximum power density (PDmax ) of 82.3 and 72.6 mW cm-2 in 2 and 10 m methanol solution, respectively. The ratio of PDmax in 10 m methanol solution to the value in 2 m methanol solution is as high as 88%. The CSPI-T-10 is promising proton exchange membrane candidate for DMFC application.

A Novel Hydrophobic Polyimide Film with Sag Structure Derived from Multi-Hybrid Strategy.

Polyimide (PI) film with hydrophilic greatly limits their application in the field of microelectronic device packaging. A novel hydrophobic PI film with sag structure and improved mechanical properties is prepared relying on the reaction between anhydride-terminated isocyanate-based polyimide (PIY) containing a seven-membered ring structure and the amino-terminated polyamide acid (PAA) via multi-hybrid strategy, this work named it as hybrid PI film and marked it as PI-PIY-X. PI-PIY-30 showed excellent hydrophobic properties, and the water contact angle could reach to 102°, which is 20% and 55% higher than simply PI film and PIY film, respectively. The water absorption is only 1.02%, with a decrease of 49% and 53% compared with PI and PIY. Due to that the degradation of seven-membered ring and generation of carbon dioxide led to the formation of sag structure, the size of sag structures is ≈16.84 and 534.55 nm for in-plane and out-plane direction, which are observed on surface of PI-PIY-30. Meanwhile, PI-PIY-30 possessed improved mechanical properties, and the tensile strength is 109.08 MPa, with 5% and more than 56% higher than that of pure PI and PIY film, showing greatly application prospects in the field of integrated circuit.

Soluble Polyimide Coated UHMWPE Fibers with Multiple Property Enhancements: Surface Activity, Tensile Strength, Heat Resistance, Acid Resistance, and Erasability.

Ultrahigh molecular weight polyethylene (UHMWPE) fibers possess excellent mechanical properties, yet their applications are severely limited by surface inertness and low melting points. To enhance surface activity and temperature resistance, soluble polyimide (PI) is applied to the surface of UHMWPE fibers. A mussel-inspired biomimetic polycatechol/polyamine (PA) coating is initially constructed on the UHMWPE fiber surface by oxidative self-polymerization, serving as a secondary reaction platform. Subsequently, multifunctional UHMWPE-PA-PI fibers are prepared by depositing soluble PI on the fiber surface via impregnation. The PA and PI layers are firmly bonded by hydrogen bonding interactions and physical adhesion. The results show that the PI-coated UHMWPE fiber surface exhibits enhanced chemical activity, hydrophilicity, and thermal stability, with an increased thermal decomposition temperature of approximately 30 °C. Compared to pristine UHMWPE, the breaking force of UHMWPE-PA-PI fibers increases by 14.9%, and the interfacial adhesion strength between the fiber and rubber improves by 65.5%. The PI coatings also provide thermal insulation, acid resistance, and erasability functionalities. This modification strategy is highly efficient, simple, and less damaging, offering a novel solution to address UHMWPE fibers' surface inertness and temperature intolerance.

Is a Vitrimer with a High Glass Transition Temperature Available? A Case Study on Rigid Polyimides Cross-Linked with Dynamic Ester Bonds.

Vitrimers, possessing associative covalent adaptable networks, are cross-linked polymers exhibiting malleable (glass-like) feature and recyclable and reprocessable (thermoplastics-like) properties. The dynamic behaviors of vitrimer are dependent on both chain/molecular mobility (glass transition temperature, Tg) and dynamic bond-exchanging reaction rate (topology freezing transition temperature, Tv). This work aims on probing the effect of high Tg on the stress relaxation and physical recyclability of vitrimers, employing a polyimide cross-linked with dynamic ester bonds (Tg: 310 °C) as the example. Due to its high Tg and chain rigidity, the cross-linked polyimide does not exhibit a high extent of stress relaxation behavior at 320 °C (10 °C above its Tg), even though the temperature is much higher than the hypothetical Tv. While raising the processing temperature to 345 °C, the cross-linked polyimide exhibits a stress relaxation time of about 3300 s and physical malleability. Nevertheless, side reactions may occur in the recycling and reprocessing process under the harsh condition (high temperature and high pressure) to alter the thermal properties of the recycled sample. The diffusion control plays a critical role on the topography transition of a vitrimer having a high Tg. The Tg ceiling is noticeable for developments of vitrimers.

Constructing Novel High Dielectric Constant Polyimides Containing Dipolar Pendant Groups with Enhanced Orientational Polarization.

Polymer dielectrics with high dielectric constant are urgently demanded for potential electrical and pulsed power applications. The design of polymers with side chains containing dipolar groups is considered an effective method for preparing materials with a high dielectric constant and low loss. This study synthesizes and comprehensively compare the dielectric properties of novel polyimides with side chains containing urea (BU-PI), carbamate (BC-PI), and sulfonyl (BS-PI) functional groups. The novel polyimides exhibit relatively high dielectric constant and low dielectric loss values due to the enhanced orientational polarization and suppressed dipole-dipole interactions of dipolar groups. In particular, BU-PI containing urea pendant groups presents the highest dielectric constant of 6.14 and reasonably low dielectric loss value of 0.0097. The strong γ transitions with low activation energies derived from dielectric spectroscopy measurements have been further evaluated to demonstrate the enhanced free rotational motion of urea pendant dipoles. In energy storage applications, BU-PI achieves a discharged energy density of 6.92 J cm-3 and a charge-discharge efficiency above 83% at 500 MV m-1. This study demonstrates that urea group, as dipolar pendant group, can provide polymers with better dielectric properties than the most commonly used sulfonyl groups.

Highly flexible and transparent colorless polyimide substrate sandwiched between plasma polymerized fluorocarbon and InGaTiO for high performance flexible perovskite solar cells.

We integrated transparent antireflective coatings and transparent electrodes onto flexible colorless polyimide (CPI) substrates to fabricate high-performance flexible perovskite solar cells. Multifunctional PPFC/CPI/IGTO substrates were fabricated by sputtering the optimal plasma-polymerized fluorocarbon (PPFC) antireflective coating and InGaTiO (IGTO) electrode films on both sides of the CPI substrate. By applying PPFC with a low refractive index (1.38) as an antireflective coating, the transparency of the PPFC/CPI/IGTO substrate increased by an additional 1.2%. In addition, owing to the amorphous characteristics of the PPFC and IGTO layers, the PPFC/CPI/IGTO substrate showed constant sheet resistance and transmittance change even after 10,000 cycles during the bending tests. The flexible perovskite solar cells, fabricated on the PPFC/CPI/IGTO substrate, exhibited an increase in current density of 1.48 mA/cm2 after the deposition of the PPFC antireflective coating. These results confirmed that the PPFC/CPI/IGTO substrate was durable against high-temperature treatment, flexible, and exhibited excellent electrical characteristics. This enhanced the efficiency and durability of the flexible perovskite solar cells. Moreover, the hydrophobic PPFC layer allowed the self-cleaning of inflexible perovskite solar cells. Given these attributes, the PPFC/CPI/IGTO structure has been recognized as a good choice for multifunctional substrates of flexible perovskite solar cells, presenting the potential for enhancing performance.

We have confirmed the durability of PPFC/CPI/IGTO substrates against high-temperature treatment, their flexibility, transparency, and their exceptional electrical properties, suggesting them as a prime selection for FPSCs.

Sensor-Less Control of Mirror Manipulator Using Shape Memory Polyimide Composite Actuator: Experimental Work.

Integrated thin film-based shape memory polyimide composites (SMPICs) are potentially attractive for efficient and compact design, thereby offering cost-effective applications. The objective of this article is to design and evaluate a mirror manipulator using an SMPIC as an actuator and a sensor with control. A sensor-less control strategy using the SMPIC (a self-sensing actuator) with a proportional derivative combined variable structure controller (PD-VSC) is proposed for position control of the mirror in both the vertical and angular directions. The mirror manipulator is able to move the mirror in the vertical and angular directions by 3.39 mm and 10.5 deg, respectively. A desired fast response is obtained as the performance under control. In addition, some benefits from the proposed control realization include good tracking, stable switching, no overshoot, no steady state oscillations, and robust disturbance rejection. These superior properties are experimentally validated to reflect practical feasibility.