Flexible Films Research Articles

Enhancing the piezoelectric performance of composite PVDF flexible films through optimizing β phase content, investigating additive effects, step‐wise polarization, and thermal pressing time for energy harvesting applications

AbstractPolyvinylidene fluoride (PVDF), known for its piezoelectric versatility, emerges as a key contender for advancing efficient and sustainable energy harvesting in nanogenerators. This study explores the potential enhancement of piezoelectric properties in flexible PVDF polymers, employing a comprehensive approach through the solution casting method. The investigation integrates diverse additives, thermal treatments, and polarization methods to optimize performance, focusing on the impact of the β phase transition on electrical voltage generation. Utilizing the Taguchi experimental design, the study identifies optimal conditions for the composite PVDF film (OPT‐PVDF) through FT‐IR, XRD, and DSC analyses, with output voltage measurements confirming superior performance compared to pure PVDF (P‐PVDF). Specifically, BN‐doped PVDF films, with an 80% β phase content, achieve an impressive 6.48 V output voltage. This research underscores PVDF's potential for energy harvesting, emphasizing the pivotal role of optimizing β phase content, additive strategies, and the effects of polarization and thermal treatments. The study further evaluates the effect and necessity of subsequent thermal treatment and step‐wise polarization effects on the composite PVDF film material. The findings indicate that BN‐doped composite PVDF films, produced under optimal conditions, exhibit advanced piezoelectric properties.

Solution-Processed Flexible Temperature Sensor Array for Highly Resolved Spatial Temperature and Tactile Mapping Using ESN-Based Data Interpolation.

High-performance flexible temperature sensors are crucial in various technological applications, such as monitoring environmental conditions and human healthcare. The ideal characteristics of these sensors for stable temperature monitoring include scalability, mechanical flexibility, and high sensitivity. Moreover, simplicity and low power consumption will be essential for temperature sensor arrays in future integrated systems. This study introduces a solution-based approach for creating a V2O5 nanowire network temperature sensor on a flexible film. Through optimization of the fabrication conditions, the sensor exhibits remarkable performance, sustaining long-term stability (>110 h) with minimal hysteresis and excellent sensitivity (∼-1.5%/°C). In addition, this study employs machine learning techniques for data interpolation among sensors, thereby enhancing the spatial resolution of temperature measurements and adding tactile mapping without increasing the sensor count. Introducing this methodology results in an improved understanding of temperature variations, advancing the capabilities of flexible-sensor arrays for various applications.

Synthesis and Characterization of an Alicyclic Acid Anhydride Containing four Stereoisomers and the Derived Polyamideimides using Diisocyanates

AbstractAn alicyclic acid anhydride BOTA, containing four stereoisomers, racemic (1S,2R,3R,4R,5R)‐bicyclo[2.2.2]octane‐2,3,5‐tricarboxylic acid‐2,3‐anhydride (7a+7a’) and racemic (1S,2S,3S,4R,5R)‐bicyclo[2.2.2]octane‐2,3,5‐tricarboxylic acid‐2,3‐anhydride (7b+7b’), was synthesized using phthalic anhydride as the starting material. The chemical structures of the products in each step were fully characterized by NMR spectroscopy, GC‐MS, elemental analysis, and single‐crystal X‐ray diffraction. The polycondensation process involving BOTA and several diisocyanates was applied to prepare PAIs. Furthermore, PAI‐Xs were prepared using methylene diphenyl diisocyanate (MDI) and various mole ratios of BOTA and 4,4'‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA). PAI‐Xs exhibited good solubility in organic solvents such as DMSO, NMP, DMAc, GBL, DMF, and m‐cresol at room temperature. They can form flexible films with low coefficients of thermal expansion (CTE) (51‐70 ppm/°C) and high glass transition temperatures (Tg) (222‐272 °C). They also demonstrated high transparency with transmittance at 500 nm (T500nm) ranging from 77.2‐82.5%. BOTA can be a significant building block in PAI synthesis, offering an alternative to trimellitic anhydride (TMA).This article is protected by copyright. All rights reserved

Synthesis of Reusable CNF/Ag2Se Films as Visible-Light-Driven Photocatalysts for Photocatalytic Degradation of MB

AbstractIn our study’s scenario, flexible films were fabricated from TEMPO-oxidized cellulose nanofibers and silver selenide (CNF/Ag2Se) as efficient membranes for the degradation of methylene blue (MB). Different concentrations of Ag2Se particles were in situ prepared in the presence of CNF. The in-situ synthesis of Ag2Se nanoparticles in the presence of CNF was reported as efficient technique for the formation of submicrosize Ag2Se particles with a narrow size distribution and homogeneous dispersion onto CNF. TEM analysis revealed that the nanofibers had uniform width and diameter, while XRD demonstrated single-phase orthorhombic β-Ag2Se formation. 3D-FESEM showed tiny root measurer values of 28, 30, and 32.56 nm in polymeric films with 2.5, 5, and 10% Ag2Se-filled CNF. Polymeric films had visible-driven-light photocatalytic activity because the band gap fell from 4.61 eV (UV area) to 2.71 eV (visible region). The composite’s photocatalytic performance was assessed by MB degradation. 10% of CNF/Ag2Se demonstrated maximal photocatalytic activity under simulated sunlight for 60 min, pH 9, and 3 g/L composite weight. The factorial design statistical analysis showed that MB dye photodegradation is mostly affected by irradiation time and dye concentration. Environmental, social, and economic factors are all considered, making this study suitable for implementing photocatalysis to large-scale water treatment systems, which is a key component of sustainability.

Non-invasive FBG-based contact lens for continuous intraocular pressure monitoring

The intraocular pressure (IOP), or pressure inside the eye, is one of the key indicator for glaucoma diagnosis and treatment. The present work shows the design and fabrication of a non-invasive Fiber Bragg Grating (FBG) based contact lens for continuous IOP monitoring. By employing wet etching to reduce the FBG diameter, FBG based contact lens sensitivity and mechanical flexibility are enhanced. The contact lens is made of an optical fiber with a small core diameter that has an inscribed FBG of length 3 mm and is etched for a length of 40 mm to facilitate coiling the eFBG during fabrication. The soft contact lens was fabricated using flexible thin film technology with a transparent and flexible etched Fiber Bragg Grating (eFBG) integrated within flexible polydimethylsiloxane (PDMS) for sensing corneal deformations brought about by IOP variations. Experimental studies on the bionic eyeball model show that the Bragg wavelength shift is highly linear (r2 = 0.9694), with a very good sensitivity of 49.243 pm/mmHg in the IOP pressure range of 0 to 50 mmHg. Due to its ease of fabricating, simplicity of design, and ability to continuously measure pressure with good repeatability and stability, the proposed sensor thus offers a potential solution for IOP monitoring.

Asymmetric optical properties and bandgap shift of pre-strained flexible ZnO films

Strain engineering has been extensively explored to modulate the various intrinsic properties of flexible inorganic semiconductor films. However, experimental characterization of tensile and compressive strain-induced modulation of optoelectronic properties and their differences has not been easily implemented in flexible inorganic semiconductor films. Herein, the strain-dependent structural, optical, and optoelectronic properties of flexible ZnO films under pre-tensile and pre-compressive strains are systemically investigated by a Mueller matrix ellipsometry-based quantitative characterization method combined with x-ray diffraction and first-principle calculation. With extended prestress-driven deposition processing under bi-direction bending modes, pre-tensile and pre-compressive strains with symmetric magnitudes can be achieved in flexible ZnO films, which allows precise observation of the strain-driven asymmetric modulation of optoelectronic properties. When the applied prestrain varies approximately equally from 0% (baseline) to −0.99% (compression) and 1.07% (tensility), respectively, the relative changes for the c-axis lattice constant are 0.0133 and 0.0104 Å, respectively. Meanwhile, the dependence factors of the bandgap energy on the pre-compression and pre-tensile strains were determined as −0.0099 and −0.0156 eV/%, respectively, and the complex refractive index also presents an asymmetric varying trend. With the help of the strain–stress analysis and the first-principle calculation, the intriguing asymmetric strain-optical modulation effect could be attributed to the biaxial strain mechanism and the difference in the deformation potential between the two prestrain modes. These systematic investigation consequences are thus promising as a basis for the booming applications of the flexible inorganic semiconductor ensemble.

Largely enhanced performance of Cu2Se film by doping sulfur for flexible thermoelectric generators

Herein, a facile method to prepare flexible S-doped Cu2Se thermoelectric films on porous nylon membranes is developed. First, S-doped Cu2Se powders with nominal compositions of Cu2Se1-xSx (x = 0, 0.02, 0.04, or 0.06) are synthesized by a hydrothermal method. Then, the as-prepared powders are deposited onto nylon substrates by vacuum-assisted filtration and hot-pressing. By adjusting the amount of S doping, the carrier concentration and mobility of the films are tuned, and the thermoelectric properties of the films are effectively optimized. As a result, the Cu2Se0.96S0.04 film displays a highest power factor of ∼662.2 μW m−1 K−2 at 300 K, representing one of the highest values reported for Cu2Se-based flexible films. The film also exhibits excellent flexibility (after 1500 bending cycles around a 4 mm radius rod, 90.8% of the initial electrical conductivity is retained). Additionally, a six-leg flexible thermoelectric generator is assembled with the Cu2Se0.96S0.04 film and outputs a peak power of 1.89 μW at a temperature difference of 23.1 K. This work presents a new method for preparing cost-effective and high-performance Cu2Se flexible thermoelectric films.

Bias-voltage dependence of structure in Mn–Ni–O/mica flexible films for high precise temperature sensing up to 600 °C

Mechanically deformable flexible temperature sensors are being used to fabricate next-generation smart electronics, but improving their high-temperature application range is still a major challenge. In this work, in pursuit of excellent performance, a series of Mn–Ni–O ultrathin flexible thermal thin films with dual-phase structure were successfully prepared by magnetron sputtering using the bias voltage adjustment method. The interactions of grain density, ionic valence and phase structure on the performance of high-temperature NTC are emphasized. By overcoming the significant drawbacks of the flexible thermal films such as poor stability and narrow temperature range under high temperature conditions, excellent thermal performance with a wide temperature range from 200 °C to 600 °C and a resistance drift rate as low as 1.5 % has been achieved. This opens up innovative prospects for the design and application of flexible high-temperature thermal materials.

X-ray excited broadband blue emitting Lu2(1-x)Bi2xO3-PMMA thin films for high resolution imaging

In this paper, cubic-phase Lu2O3:Bi3+ nanoparticles, with a range of sizes between 110 and 180 nm, were obtained by a combination of co-precipitation and thermal annealing techniques. For these nanoparticles upon UV or X-ray excitation, strong broadband emission peaks at 410 and 480 nm corresponding to Bi3+ occupying S6 and C2 (Lu3+(S6) and Lu3+(C2)) sites, respectively, can be observed. On the basis of the concentration-dependent luminescence intensity ratios (I480(C2)/I410(S6)) of Bi3+(C2) to Bi3+(S6), the energy transfer from Bi3+(S6) to Bi3+(C2) can be confirmed at high Bi3+ concentration. In particular, their X-ray absorption coefficient, emission wavelength, afterglow level (60 ppm) and response time (465 ns) are almost comparable to those of the commercial Bi4Ge3O12 crystals. By the means of dispersing Lu1.98Bi0.02O3 nanoscintillators into organic polymer (PMMA)-acetone solution, the Lu1.98Bi0.02O3-PMMA flexible composite films exhibiting rapid response to X-ray photons, high X-ray sensitivity and radiation resistance, good mechanical performance and excellent environmental stability were prepared using a spin-coating technique. On the surface of X-ray imaging screen formed by the flexible dense composite films, the spatial resolution can reach to 6.0 lp/mm at a safe irradiation dose (4.6 μGy). Meanwhile, for the imaging screen using the flexible composite films after bended for thousands of times, we can observe clear image of each reed gap (300 μm) of the music box. For the Lu2O3:Bi3+-PMMA composite films, our results suggest that not only their scintillation properties are almost comparable to those of the commercial broadband Bi4Ge3O12 crystals, but also they might be applied in large-area and non-planar X-ray imaging.

Molybdenum doped indium oxide thin films grown on mica substrates with high near-infrared transparency and electron mobility for flexible optoelectronic and spintronic applications

In the era of the artificial intelligence, flexible multifunctional films that combine optical transparency, electrical conductivity, and ferromagnetism are highly beneficial for many advanced applications. Herein, we fabricated a flexible magnetic transparent conductor molybdenum doped indium oxide (IMoO) thin film on a mica substrate using a pulsed laser deposition (PLD) technique. The valence states of Mo dopants were determined to be Mo4+ and Mo6+ by X-ray photoelectron spectroscopy (XPS) analysis. From the measured optical transmittance spectrum, average visible (Vis) and near-infrared (NIR) transmittance (Tave_Vis and Tave_NIR) values in IMoO film are calculated to be 85.9 % and 85.4 %, respectively. The IMoO film shows an electron mobility (μe) of around 113 cm2 V−1 s−1 and a sheet resistance (Rs) of 69 Ω. We illustrate the benefits of Mo doping, which leads to increased NIR transparency and μe compared to commercially available tin-doped indium oxide (ITO). On the other hand, the IMoO film shows clear magnetic hysteretic behaviors at room temperature, indicating the presence of ferromagnetism. The main origin of the ferromagnetism is presumably attributed to the Mo4+ ions with an electronic configuration of 4 d2. Bending cyclic tests reveal favourable mechanical durability and bending stability in the IMoO/mica films. Our systematic investigation demonstrates that IMoO film possesses a superior optoelectronic performance beyond ITO, Mn-doped indium oxide (IMnO), and Sn-Mn-codoped indium oxide (ITMnO), substantiating the potential of the IMoO/mica film as a high-performance transparent conductive magnetic material for flexible optoelectronic and spintronic applications.

Incorporation of nanoparticles in silk fibroin solution: Toward water‐stable silk fibroin films possessing silk I structure

AbstractWater‐stable silk fibroin (SF) films are normally prepared by transforming the secondary structure of SF, from amorphous silk I (random coils) to silk II (β‐sheet), via physical or chemical means. Although mechanically strong, these films are generally brittle. Herein, we prepared water‐stable flexible SF films possessing silk I rather than silk II structure. Films were prepared by casting SF solution possessing SF nanoparticles induced by two different methods: (1) pre‐prepared SF nanoparticles by ethanol were added into SF solution; (2) nanoparticles were induced in SF solution via autoclaving. These films were compared with each other and with water‐annealed and methonol‐annealed films for their secondary structure and physical properties. The as‐prepared films were primarily composed of silk I structure, as validated by x‐ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. However, the water‐annealed and methanol‐annealed films exhibited silk II structure. The films prepared by induction of nanoparticles were water‐stable, transparent, mechanically strong (tensile strength as high as 5.14 ± 1.43 MPa), exhibited tunable degradation and sustained drug release properties. As for mechanical properties, these films displayed 4 times and 12 times improved mechanical ductility as compared with water‐annealed and methanol‐annealed films, respectively. Moreover, these films exhibited fast enzymatic degradation as compared with their counterparts with silk II structure. These films hold great promise as a biomaterial for tissue engineering applications especially where flexibility and fast degradation of scaffold are important.

Fabrication and Characterization of Non-Conventional Starch Based Biofilms Employing Different Plasticizers

Increasing stress on environmental awareness has promoted the use of alternative strategies for common petrochemical based plastic sources to environmentally friendly biofilms and packaging materials. Food by products and underutilised indigenous plants sources are rich in biopolymers which can naturally decompose. The present study focusses on preparations of bioplastics from unconventional starch sources of litchi seed and churkha tuber as novel initiative to combat environmental pollution along with valorisation of undervalued plant sources and agrobased wastes. Ternary blend films of poly vinyl alcohol, starch, plasticizers like (glycerol, sorbitol, mannitol, propylene glycol, polyethylene glycol), citric acid prepared by casting technique produced best result. Comparative study of test samples (TH11, TH12, TH13, TH14 etc) with standardized thin films (TH1, TH2, TH3 etc.) showed variation in appearance, water activity, thickness, since the starch differ in their compositions, gelatinization and gelation time and temperature. High amylose containing litchi seed starch forms firm and more flexible films in comparison to low amylose containing churkha tuber starch. Maximum hygroscopicity was recorded in case of TH1 (77.4%) while thickness was maximum in case of TH12 (0.18 mm). Micro structural analysis clearly showed the nature of crosslinking between starch molecule and different plasticizers. The sensory analysis of food packed with the best among the formularized thin films showed mild change in taste while the other parameters remain same as normal. Better acceptability was in case of TH12 wrapped food rather than TH1. Thus, fabrication of biodegradable packaging is considered as the most sustainable alternative for food preservation. Int. J. Appl. Sci. Biotechnol. Vol 12(1): 29-38.

Scalable one-step synthesis of reduced graphene oxide: Towards flexible transparent conductive films and active supercapacitor electrodes

The reduced graphene oxide (rGO) thin films have attracted much attention in flexible electronic devices and supercapacitors (SCs). However, the chemical reduction mechanism of GO needs to be clarified, and the one-step process at low temperatures for preparing high-quality rGO thin films from GO dispersions is still blank in the research field. Here, we propose a one-step operation to spray GO dispersions onto substrate or current collector under a hydroiodic acid (HI) atmosphere while simultaneously achieving the preparation of rGO thin films. This pioneering metal-free, transfer-free, fast, low-temperature, environmentally friendly, and scalable spraying technology enables large-scale production of high-quality rGO. This method realizes the preparation of highly conductive and high transmittance rGO thin films on flexible polyimide and polyethylene terephthalate substrates, as well as the preparation of rGO thin films on current collectors as SCs electrodes. Density functional theory calculations show that oxygen-containing functional groups on the surface of GO exhibit a stronger adsorption energy for HI, and have a low energy barrier during reduction by HI. Ab initio molecular dynamics simulated the possible reduction reaction path between GO and HI at 90 °C, demonstrating that HI molecules can effectively reduce GO. Furthermore, the sheet resistance of the transparent conductive film created using the method developed in this study reaches approximately 1000 Ω/sq (80 % transparency), and the specific capacitance of the SCs electrode film created in this method is 433.2 F/g (5 mV/s, 1 M H2SO4). Our study not only validates the efficacy of the one-step synthesis method for rGO thin films but also provides theoretical insights into the underlying reaction mechanism. This work holds significant promise for advancing applications in various electronics by facilitating large-scale production of high-quality rGO thin films.

Biodegradable ferroelectric molecular crystal with large piezoelectric response.

Transient implantable piezoelectric materials are desirable for biosensing, drug delivery, tissue regeneration, and antimicrobial and tumor therapy. For use in the human body, they must show flexibility, biocompatibility, and biodegradability. These requirements are challenging for conventional inorganic piezoelectric oxides and piezoelectric polymers. We discovered high piezoelectricity in a molecular crystal HOCH2(CF2)3CH2OH [2,2,3,3,4,4-hexafluoropentane-1,5-diol (HFPD)] with a large piezoelectric coefficient d33 of ~138 picocoulombs per newton and piezoelectric voltage constant g33 of ~2450 × 10-3 volt-meters per newton under no poling conditions, which also exhibits good biocompatibility toward biological cells and desirable biodegradation and biosafety in physiological environments. HFPD can be composite with polyvinyl alcohol to form flexible piezoelectric films with a d33 of 34.3 picocoulombs per newton. Our material demonstrates the ability for molecular crystals to have attractive piezoelectric properties and should be of interest for applications in transient implantable electromechanical devices.

Enhanced dielectric performance and thermal conductivity of the polyetherketoneketone composite films prepared via a facile template spray coating method

Polyetherketoneketone (PEKK) is a specialized engineering plastic renowned for its exceptional strength, high temperature resistance and chemical resistance. However, the high melting point of PEKK restricts its processing methods to traditional techniques such as melt extrusion, hot pressing, and molding, significantly limiting its application in the field of microelectronic devices. In this study, a facile template spray coating method was proposed to prepare highly flexible PEKK films. Furthermore, functionalized boron nitride-carbon nanotube (BN-CNT) hybrid fillers were prepared and incorporated into the PEKK matrix. The results demonstrated that when the content of BN-CNT hybrid filler was 5 wt%, the dielectric constant of the composite film ranges from 2.2 to 1.8 in the frequency range of 100–200000 Hz, with a dielectric loss value below 0.03. When the content of the hybrid filler increased to 20 wt%, the enhanced thermal conductive network results in a 640% increase in thermal conductivity compared to pure PEKK. The enhanced thermal conductivity of the composite films promoted heat dissipation of the computer CPU and accelerated the cooling rate. These findings demonstrate the great potential of the PEKK composite films for diverse applications in microelectronic devices.

Investigation into thermoelectric performance of a flexible n-type nanocomposite film from the AgxSe nanotube composited with PPy

Silver selenide (Ag2Se) has turn up as a promising n-type thermoelectric (TE) material. Especially, the Ag2Se nanotubes may be more attractive in view of their one-dimensional hollow tubular nanostructure. Regrettably, the TE application of Ag2Se nanotubes has not yet been reported so far, probably due to their hard accessibility and poor processability. In this work, we developed a simple and efficient template-free electrochemical deposition method for preparing AgxSe nanotubes, and thus investigated the TE application of the AgxSe-nanotube films electrochemically composited with polypyrrole (PPy). It was found that the incorporation of PPy into the n-type AgxSe-nanotube films not only settled the issues of their high brittleness and easy oxidation, but also significantly improved their TE performance through the synergistic effects. Consequently, the AgxSe nanotube/PPy composite film achieved a maximum power factor of 282.8 ± 16.5 μW m−1 K−2, which is nearly twice that of the pure AgxSe-nanotube film.

Multi-interfacial bridging engineering of flexible MXene film for efficient electromagnetic shielding and energy conversion

Accompanied by the progressive development of electronic equipment, excellent electromagnetic interference (EMI) shielding materials display a satisfying prospect in protecting electronic devices against electromagnetic pollution/radiation, while integrating energy conversion. Heretofore, it remains a conundrum to availably construct thin films with multi-interfacial bridging engineering as multifunctional shielding devices. To effectively achieve electromagnetic wave attenuation and integrate energy conversion, a co-mixed vacuum-assisted filtration strategy is designed to synthesize Au@MXene/cellulose nanocrystal/dodecylbenzenesulfonic acid-doped polyaniline (AMCP) films. Profited from the interfacial engineering, the total EMI shielding effectiveness (SE) can be increased by 27 % with the highest value of 67.9 dB. MXene with localized surface plasmon resonance characteristics gives the composite films good energy conversion performance, that is, the composite film can be rapidly heated up to 100 °C under the irradiation of an infrared lamp, and its surface temperature remains stable after continuous irradiation. Additionally, the infrared emissivity is as low as 0.173 within the 8–14 μm, which is necessary to adapt various application scenarios. Therefore, it is reliable that the AMCP films constructed by multicomponent offer a facile strategy for MXene-based EMI shielding devices with integration characteristics.

Highly flexible carbon nitride-polyethylene glycol-cellulose acetate film with photocatalytic antibacterial activity for fruit preservation

Cellulose acetate film, as a biodegradable and biomass-derived material, has great potential applications in food packaging. However, the poor mechanical and antibacterial properties limit its applications. Herein, a highly flexible carbon nitride-polyethylene glycol-cellulose acetate (CN-PEG-CA) film was successfully prepared by combining graphitic carbon nitride (g-C3N4) photocatalyst with cellulose acetate (CA). The g-C3N4 enables the film with antibacterial activity, as a green photocatalyst. PEG softens the rigid polymer CA and crosslinks CA, PEG, and g-C3N4 together by hydrogen bonding, as a flexible crosslinker. X-ray diffractometer (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectrum (FT-IR) characterizations confirmed the successful preparation of the CN-PEG-CA film. The mechanical property tests demonstrated that adding PEG increased the elongation at break of the film by about 4 times. The composite film had high antibacterial activity, and the bactericidal rates on Escherichia coli and Staphylococcus aureus were 99.98 % and 99.89 %, respectively. It effectively extended the shelf life of strawberries to 96 h and effectively maintained the quality of strawberries during storage. After 96 h, the weight loss rate of strawberries packaged with 15 % CN-PEG-CA film was 21.83 %, vitamin C content was 45.47 %, titratable acidity content was 0.89 %, and color, hardness and total soluble solids were well maintained. And biocompatibility test results showed that the film was safe and nontoxic. From the ecological and economic point of view, the highly flexible and biodegradable films with efficient photocatalytic antibacterial activity synthesized in this paper have great potential in the field of food packaging.

Mechanically Tunable Circularly Polarized Luminescence of Liquid Crystal‐Templated Chiral Perovskite Quantum Dots

Endowing perovskite quantum dots (PQDs) with circularly polarized luminescence (CPL) offers great promise for innovative chiroptical applications, but the existing strategies are inefficient in acquiring stimuli‐responsive flexible chiral perovskite films with large, tunable dissymmetry factor (glum) and long‐term stability. Here, we report a strategy for the design and synthesis of luminescent cholesteric liquid crystal elastomer (Lumin‐CLCE) films with mechanically tunable CPL, which is enabled by liquid crystal‐templated chiral self‐assembly and in situ covalent cross‐linking of judiciously designed photopolymerizable CsPbX3 (X = Cl, Br, I) PQD nanomonomers into the elastic polymer networks. The resulting Lumin‐CLCE films showcase circularly polarized structural color in natural light and noticeable CPL with a maximum glum value up to 1.5 under UV light. The manipulation of CPL intensity and rotation direction is achieved by controlling the self‐assembled helicoidal nanostructure and the handedness of soft helices. A significant breakthrough lies in the achievement of a reversible, mechanically tunable perovskite‐based CPL switch activated by biaxial stretching, which enables flexible, dynamic anti‐counterfeiting labels capable of decrypting preset information in specific polarization states. This work can provide new insights for the development of advanced chiral perovskite materials and their emerging applications in information encryption, flexible 3D displays and beyond.

Transferable G/Au Film for Constructing a Variety of SERS Substrates.

Surface-enhanced Raman scattering (SERS), as one of the most powerful analytical methods, undertakes important inspection tasks in various fields. Generally, the performance of an SERS-active substrate relies heavily on its structure, which makes it difficult to integrate multiple-functional detectability on the same substrate. To address this problem, here we designed and constructed a film of graphene/Au nanoparticles (G/Au film) through a simple method, which can be conveniently transferred to different substrates to form various composite SERS substrates subsequently. By means of the combination of the electromagnetic enhancement mechanism (EM) and the chemical enhancement mechanism (CM) of this structure, the film realized good SERS performance experimentally, with the enhancement factor (EF) approaching ca. 1.40 × 105. In addition, the G/Au film had high mechanical strength and had large specific surface area and good biocompatibility that is beneficial for Raman detection. By further transferring the film to an Ag/Si composite substrate and PDMS flexible film, it showed enhanced sensitivity and in situ detectability, respectively, indicating high compatibility and promising prospect in Raman detection.