Color Switching Research Articles

A Facile Electrochemical Strategy for Achieving a High-Conductivity Polypyrrole Derivative with Intrinsic Metallic Transport as a High-Performance Electrochromic Conducting Polymer Film.

Conjugated polymer electrochromic materials (PECMs) with tailored optical and electrical properties are applied in smart windows, electronic displays, and adaptive camouflage. The limitation in the electrical conductivity results in slow and monotonous color switching. We present a polypyrrole film incorporated with a toluene-p-sulfonic group (PPy-TSO-F), via a one-step electrodeposition technique. The PPy-TSO-F thin film (110 nm) achieves an impressive electrical conductivity of 1011 S cm-1, a high carrier mobility of 82 cm2 V-1 s-1, and intrinsic metallic electronic behavior. It demonstrates exceptionally reversible multicolor switching, transitioning from emerald green (-1.5 V), to bluish green (-1.4 V), bright yellow (-1.2 V), greenish yellow (-0.6 V), reddish brown (0.1 V), dark brown (0.3 V), and atrovirens (0.6 V). The fast charge transport and high carrier mobility render the film with an ultrafast electrochromic switching speed of 0.01 s/0.02 s. This research provides a new route to designing ultrafast multicolor switching PECMs with metallic charge transport.

A high-capacity and self-healable electrochromic system based on I0/CuI conversion reaction

Constructing electrochromic devices (ECDs) requires high-performance electrochromic electrodes with not only high color contrasts, but also large charge storage capacities. In this paper, a I0/CuI conversion-type electrochromic system is developed, achieving reversible and profound color switching between colorless transparent and dark brown, while delivering a large charge storage capacity of 246.7 mA h g−1. To improve switching durability, a multifunctional P10 (Polyquaternium-10) binder is introduced into the electrode, which can effectively confine the polyiodide intermediates and suppress the shuttle effect. At the same time, the CuI/Cu redox couple is further activated by controlling the applied voltage. The generated Cu from this couple can spontaneously react with residual I0 species and facilitate the conversion from I0 to CuI, and therefore in-situ rejuvenate the degraded electrochromic performance. Thanks to these rational designs, this electrochromic electrode achieves rapid response speeds (tcoloring: 14 s, tbleaching: 5 s), high optical modulation amplitude (73.4 % at 500 nm), decant coloration efficiency (57.0 cm2 C−1) and impressive cycle stability (without performance degradation after 150 cycles). This work provides a novel electrochromic system for the construction of high-performance electrochromic devices.

Photomodulation of Charge Transfer through Excited‐State Processes: Directing Donor‐Acceptor Binding Dynamics

AbstractModulating charge transfer (CT) interactions between donor and acceptor molecules may give rise to unique dynamic changes in physicochemical properties, exhibiting great importance in supramolecular chemistry and materials science. In this work, we demonstrate the first instance of reversible photomodulation of donor‐acceptor (D−A) CT interaction in the solid state. Pyridinium‐based chromophore featuring π‐conjugated D−A structures can not only function as a good electron acceptor to undergo photoinduced electron transfer (ET) or engage in intermolecular CT interaction, but also exhibit unique dual emission depending on the excitation wavelengths. The rotatable C−C single bonds within D−A pairs enhance the tunability of molecular structure. Through the synergy of a photoinduced ET and an excited‐state conformational change, the intermolecular CT interaction can be switched on and off by alternate light irradiation to enable reversibly modulation of the affinity between donor and acceptor molecules, accompanied by visual color switching and fluorescence on‐off as feedback signals.

Structural Design of Hybrid Manganese(II) Halides for High Quantum Efficiency and Specific Response to Methanol.

Manganese(II) halides have been a new generation of optoelectronic materials due to their fascinating luminescent properties, however, lacking specific solvent-responsive analogues with high quantum efficiency. Herein, we prepared three single crystals, [Pr(MIm)2][MnBr4] ([Pr(MIm)2]2+ = 1,3-di(methylimidazolium)-propane, Compound 1), [Pr(EIm)2][MnBr4] ([Pr(EIm)2]2+ = 1,3-di(ethylimidazolium)-propane, Compound 2), and [Bu(MIm)2][MnBr4] ([Bu(MIm)2]2+ = 1,4-di(methylimidazolium)-butane, Compound 3), where different Bola-type cations were chosen as organic components to separate [MnBr4]2- tetrahedrons. All three compounds emitted bright green light with excellent quantum yields of 95.3, 80.0, and 96.2%, benefiting from the large Mn···Mn distance. More interestingly, Compound 3 showed a highly selective response to methanol in a series of tested organic solvents, with a rapid and reversible change in emission color from green to red. The single crystal of [Bu(MIm)2][MnBr4]·CH3OH with red emission proved that the luminescence switching was attributed to the adsorption of CH3OH molecules into the lattice space in the form of the O-H···Br hydrogen bonds. To our knowledge, for tetrahedrally coordinated Mn(II) species, the reversible emission color switching between green and red triggered by a solvent without the change of coordination number is achieved for the first time, providing promising applications for the specific detection of methanol.

Molybdenum-Modified Niobium Oxide: A Pathway to Superior Electrochromic Materials for Smart Windows and Displays

Electrochromic materials enable the precise control of their optical properties, making them essential for energy-saving applications such as smart windows. This study focuses on the synthesis of molybdenum-doped niobium oxide (Mo-Nb2O5) thin films using a one-step hydrothermal method to investigate the effect of Mo doping on the material’s electrochromic performance. Mo incorporation led to distinct morphological changes and a transition from a compact granular structure to an anisotropic rod-like feature. Notably, the MN-3 (0.3% Mo) sample displayed an optimal electrochromic performance, achieving 77% optical modulation at 600 nm, a near-perfect reversibility of 99%, and a high coloration efficiency of 89 cm2/C. Additionally, MN-3 exhibited excellent cycling stability, with only 0.8% degradation over 5000 s. The MN-3 device also displayed impressive control over color switching, underscoring its potential for practical applications. These results highlight the significant impact of Mo doping on improving the structural and electrochromic properties of Nb2O5 thin films, offering improved ion intercalation and charge transport. This study underscores the potential of Mo-Nb2O5 for practical applications in energy-efficient technologies.

Putting the squeeze on valence tautomerism in cobalt-dioxolene complexes

Molecules that can reversibly switch between electronic states under an external stimulus are of interest to numerous applications. Complexes of open shell metal ions with redox active ligands undergo valence tautomerism, resulting in magnetic, colour and structural switching, relevant to data storage and actuators. However, the precise structural changes occurring during valence tautomerism in the solid state are unclear due to the lack of atomic-resolution characterization. Here, variable temperature and high-pressure single crystal X-ray diffraction is used to characterize valence tautomerism in two isostructural cobalt complexes, [Co(bis(6-methyl-2-pyridylmethyl) amine)(3,5-di-tert-butyl-1,2-dioxolene)]+ and [Co(tris(6-methyl-2-pyridylmethyl)amine)(3,5-di-tert-butyl-1,2-dioxolene)]+ to atomic resolution. The less sterically hindered dimethylated complex exhibits two-step thermally-induced interconversion between the high-spin CoII-seminquinonate and low-spin CoIII-catecholate forms (valence tautomerism) at 155 and 95 K due to the presence of two symmetry-independent complexes. In contrast, the more sterically hindered trimethylated complex does not display thermal valence tautomerism. Both complexes exhibit unique behaviour under high pressure. The dimethylated species undergoes gradual, one-step valence tautomerism in both symmetry-independent complexes concurrently between 0.43 GPa and 1.30 GPa. In the trimethylated species, pressure is sufficient to overcome steric hindrance, leading to one-step valence tautomerism between 2.60 GPa and 3.10 GPa, demonstrating pressure-triggered valence tautomerism in a thermally inactive complex. This study is among the few investigations using in situ high-pressure single crystal X-ray diffraction to achieve atomic-level structural characterization of valence tautomerism, aiding the development of robust structure-property relationships in these types of complexes.

Structural Rigidification Strategy Based on Self-Assembly Enabled Reversible Excited-State Conversion of Iridium(III) Complexes for Multiple-Stimulus-Responsive Data Encryption.

Stimulus-responsive chromic materials exhibit color-switching properties under specific external stimuli and have been widely used in various fields. Transition-metal complexes show great potential applications as promising candidates for stimulus-responsive chromic materials, as their excited states not only depend on the chemical composition but are also affected by the intermolecular stacking modes. Owing to the intrinsic difficulty in the ordered stacking of the octahedral configuration, changing the stacking modes of iridium(III) complexes for multiple-stimulus responsiveness remains a significant challenge. In this work, we propose a structural rigidification strategy based on self-assembly to reversibly regulate the excited states of iridium(III) complexes, therefore achieving color switch under different stimulus conditions. We prepare cationic iridium(III) complexes by using tetrakis(perfluorophenyl)-borate ([B(PhF5)4]-) as the counterion, whose matching tetrahedral configuration and electron-deficient aromaticity enables polar-π interaction with the octahedral iridium(III) cations, inducing self-assembly to form structural rigidification. The structural rigidity restricts the large conformational changes of the metal-to-ligand charge transfer (3MLCT) excited state, and facilitates the conversion from the 3MLCT to the ligand-center (3LC) excited state in aggregated states. The excited-state conversion results in a 54 nm blue shift (from yellow to sky blue) in the photoluminescence spectra. As a result, we report a series of cationic iridium(III) complexes with different responses to low temperature, vapor fuming, and mechanical force, therefore achieving multiple-stimulus-responsive data encryption. Our work provides a novel strategy to achieve ordered stacking of octahedral complexes, shows a deeper understanding of the photophysical processes of transition-metal complexes, and offers a new perspective to develop multiple-stimulus-responsive chromic materials.

High-Performance Electro-optical Dual-Mode Color-Changing and Energy Storage Device Based on Mo-Doped WO3 and TiO2/NiO Thin Films.

Under optical and electrical control, a multifunctional electro-optical dual-control color-changing and energy storage device not only realizes fast color conversion but also achieves good energy storage performance. In this work, Mo-doped WO3 (Mo-WO3) films were prepared by a one-step hydrothermal method, among which the 2 at. % Mo-doped WO3 film has the best electrochromic and energy storage performance. Meanwhile, TiO2/NiO composite films were prepared by the hydrothermal method and electrodeposition method. The TiO2/NiO/N719 photoanode was prepared by the dip-dyeing method on the TiO2/NiO composite film. The results show that the TiO2/NiO-10s/N719 composite film has excellent photoelectric conversion and energy storage properties. Finally, choosing Mo-WO3 as the cathode and the TiO2/NiO/N719 film as the anode, a multifunctional electro-optical dual-control Mo-WO3@TiO2/NiO/N719 color-changing and energy storage device was constructed. Under electrical control, it shows a fast color switching rate (the coloring/bleaching time is 4.1/2.9 s), excellent coloration efficiency (62.1 cm2/C), obviously improved area capacitance (90.4 mF/cm2), and excellent cycle stability. Under optical control, it shows a shortened optical response time (the coloring/bleaching is 70.3/158.9 s), excellent coloration efficiency (58.2 cm2/C), better area capacitance (51.1 mF/cm2), and excellent photoelectric conversion efficiency.

Constructing Bionic Perovskite Smart Photovoltaic Windows with Switchable Colors and High Cycling Stability.

Smart photovoltaic windows (SPWs) provide a high-efficiency and energy-saving strategy owing to the dual capabilities of electricity generation and sunlight modulation achieved by tunable colors and transmittances. Due to the deterioration of chromic process on photovoltaic layers, SPWs usually suffer from poor cycling stability. Moreover, thermochromic SPWs with a multilayer structure usually change transmittance without reversible color transitions. To address these issues, inspired by chameleon skin, bionic SPWs are designed and constructed by integrating hydrogel, CsPbBr3 semitransparent perovskite solar cells (ST-PSCs), and transparent polymer film. The SPWs realize reversible transitions between transparent green (25°C) and opaque yellow (45°C) states in a short duration (2min) under natural conditions. By optimizing perovskite film and ultrathin-metal electrodes, CsPbBr3 ST-PSCs achieve a good trade-off between transmittance and efficiency, delivering the highest photovoltaic efficiency (8.35%) and a record light utilization efficiency (4.43). Ultimately, the multilayer SPWs maintain stable optical properties and more than 88% initial conversion efficiency after 100 transition cycles, presenting excellent cycling stability. This study proposes a novel approach and device structure for SPWs with high cycling stability, switchable colors, and switchable transmittances. It also paves the way for smart photovoltaic deployment in buildings and many other fields.

Polarization-switchable structural colors generated by AlN metasurfaces and the effect of different substrates

Metasurfaces have the capability to boost the generation of distinct colors by improving the interaction between surface materials and photons. We present a straightforward and polarization-tunable aluminum nitride metasurface. This metasurface enables the display and concealment of the composition pattern and exhibits color switching by modifying the polarization state of the incident light. We further explore the impact of different substrates on metasurface performance. The results indicate that the full width at half maximum of the reflectance curves increases with the increase of the refractive index between the nanostructures and the substrate material, which leads to a broader dispersion of the structural colors in the spectrum. Moreover, the sizes of the nanostructures can be gradually reduced for the substrate with a high refractive index. These findings not only offer polarization-tunable structural color metasurfaces but also provide essential insights in selecting nanostructure and substrate materials, which will help in the design of nanostructures for such metasurfaces.

Smart Photovoltaic Windows for Next-Generation Energy-Saving Buildings.

The global energy system transforming from fossil fuels to renewable green energy through the adaption of innovative and dynamic green technologies. Energy-saving buildings (ESBs) are attracting extensive attention as intelligent architectures capable of significantly reducing the energy consumption for heating, air-conditioning, and lighting. They provide comfortable working and living environment by regulating and harnessing solar energy. Smart photovoltaic windows (SPWs) offer a promising platform for designing ESBs due to their unique feature. They can modulate solar energy based on dynamic color switching behavior under external stimuli and generate electrical power by harvesting solar energy. In this review, the-state-of-art of strategies and technologies are summarized putting SPWs toward high-efficiency ESBs. The SPWs are systematically categorized according to the working principle and functional component. For each type of SPWs, material and architecture engineering are focused on to optimize operation mode, optical modulation capability, photovoltaic performance and durability for giving ESBs flexible manipulation, extraordinary energy-saving effect, and high electricity power. In addition, the challenges and opportunities in this cutting-edge research area are discussed, with the aim of promoting the development of advanced multifunctional SPWs and their application in high efficiency ESBs.

Study on electro-optical dual-control color-changing and energy-storage device based on Mo-WO3 and Al-TiO2 thin film electrode

Under optical and electrical control, a multifunctional electro-optical dual-control color-changing and energy-storage device not only realizes quick color conversion, but also achieves good storage performance. In this work, Mo doped WO3 (Mo-WO3) films were synthesized through one-step hydrothermal method and N719/Al doped TiO2 (N719/Al-TiO2) films were synthesized by hydrothermal and dip-dyeing method. Eventually, choosing Mo-WO3 as cathode and N719/Al-TiO2 film as anode, a multifunctional electro-optical dual-control Mo-WO3@N719/Al-TiO2 color-changing and energy-storage device was constructed. Under electrical control, the device shows excellent coloration efficiency (73.99 cm2/C), fast color switching rate (coloring/ bleaching time is 3.6 s/1.4 s), obviously improved area capacitance (about 82.6 mF/cm2) and excellent cycle stability. Under optical control, the device also shows shortened response time (coloring/ bleaching is 64.3 s/143.4 s), outstanding coloration efficiency (70.49 cm2/C), better area capacitance (about 58.6 mF/cm2) and excellent photoelectric conversion efficiency (10.56 %).

Programmable Persistent Room Temperature Phosphorescence Switches through Wavelength-Selective Photoactivation.

Controlling multicolor persistent room-temperature phosphorescence (RTP) through photoirradiation holds fundamental significance but remains a significant challenge. In this study, we engineered a wavelength-selective photoresponsive system utilizing the Förster resonance energy transfer strategy. This system integrates a photoactivated long-lived luminescent material as the energy donor with a fluorescent photoswitch as the energy acceptor, facilitating programmable persistent luminescence switches. Distinct afterglow color states, such as initial nonemissive, green, yellow, and orange, were achieved through irradiation at 400 nm, 365 nm, and 254 nm, respectively. Based on this capability, we established an interacting network for multistate afterglow color switching among these four emissive states. In addition, we demonstrate the potential of this wavelength-selective photoresponsive system in the photo-controlled rewritable printing of multicolor afterglow images on a single thin film. This work represents a substantial step towards the fabrication of sophisticated wavelength-selective photoresponsive systems, potentially revolutionizing applications in optical data storage, security labeling, and smart displays by enabling precise control over photoresponsive behaviors under various photoirradiation wavelengths.

A versatile bioluminescent probe with tunable color.

Bioluminescence is a powerful method for imaging in vivo, but applications at the microscale are far from routine. This is due, in part, to a lack of versatile tools for visualizing dynamic events. To address this void, we developed a new platform-Bioluminescence Resonance Energy mAKe over with a Fluorescence-Activating absorption-Shifting Tag (BREAKFAST). BREAKFAST features a bright luciferase combined with a chemogenetic tag (pFAST) for rapid color switching. In the presence of luciferin and a discrete fluorogenic ligand, signal is observed via resonance energy transfer. We evaluated spectral outputs with various fluorogens and established the utility of BREAKFAST for combined fluorescence and bioluminescence imaging. Dynamic, four-color visualization was achieved with sequential ligand addition and spectral phasor analysis. We further showed selective signal quenching with a dark fluorogen. Collectively, this work establishes a new method for bioluminescence imaging at the cellular scale and sets the stage for continued probe development.

Mechanochromic Suction Cups for Local Stress Detection in Soft Robotics

Advancements in smart soft materials are enhancing the capabilities of robotic manipulators in object interactions and complex tasks. Mechanochromic materials, acting as lightweight sensors, offer easily interpretable visual feedback for localized stress detection, structural health monitoring, and energy‐efficient robotic skins. Herein, an innovative mechanochromic soft end‐effector capable of discerning local contact stresses during mechanical interactions with objects is presented and their relative position is ascertained. This system utilizes a reversible force‐induced color switch in a thin layer of spiropyran‐functionalized polydimethylsiloxane, which coats a silicone‐made suction cup. The mechanochromic suction cup is integrated with a 3D‐printed compact load‐transferring system and electronic color‐changing detection elements. The assembly may serve as a synthetic receptor for robotic actuators, discerning localized interaction forces down to 3 N. The system's resilience to varying environmental factors, including illumination, tilting, and interaction with objects of various shapes is verified. The results indicate potential for exteroceptive solutions in reconfigurable manipulation tasks without compromising the overall softness of the manipulator.

On-demand green/red light-responsive self-doped SnO2 nanoparticles for single/multi-color transitioning fabrics

Semiconductor/redox-based dual light-induced color switching systems (LCSs) with a visible light response at different wavelengths are highly sought after for efficient redox reactions. In this work, Sn2+ self-doped SnO2 has been designed as nanophotocatalysts for preparing visible light-responsive inks/fabrics with single/multi-color abilities. The self-doping of SnO2 nanoparticles results in the formation of oxygen vacancies due to charge compensation effects leading to electron-driven photoreduction and photooxidation of LSC inks. By mixing SnO2-x nanoparticles dispersions with specific redox-sensitive dyes can lead to the creation of well-designed sets of visible light-responsive semiconductor-driven LCS systems with both single-color (RGB) and multi-color (violet and green) changes. The exposure of LCS inks to green (550 nm) light culminates in the rapid photoreduction of the inks to decolorized state, while red (660 nm) light initiates the photooxidation in air. The combination of the LCS inks with –OH-rich polymers can be coated on the hydrophobic surface of the layered fabric to produce photo-responsive fabrics with single/multi-color response. The interaction of green light with the semiconductor-driven LCS systems allows the remote photo-printing of different images/letters on the LCS fabrics. Spontaneous erasure can be achieved by red light with high stability and repeatability (>35 cycles). The research in this paper provides new perspectives and insights for the development of new color-changing materials with potential applications as light-activated sensors and display units.

Robust Dual-Color Electrochromism of Vanadium Oxide Nanorods Embedded on Reduced Graphene Oxide: Unraveling the Mechanism

Vanadium pentoxide (V2O5), associated with both cathodic and anodic coloration, is considered as one of the best electrochromic (EC) materials for energy-saving smart electronics. Here we present the fabrication and detailed mechanism analysis for improving the electrochromic properties of V2O5 incorporated in a reduced graphene oxide (rGO) matrix using a facile wet chemical method. The microstructural study disclosed the formation of prominent V2O5 nanorods embedded in the rGO matrix. The optimized electrochromic film resulted in coloration (tc) and bleaching time (tb) of ∼6.2 and ∼4.8 s, respectively, much faster than the color switching kinetics of the pristine V2O5 sample (tc ∼ 19.4 s, tb ∼ 15.3 s). The more dispersed structure also ensured an approximate 400% enhancement in the optical modulation of EC film and reflected a noticeable improvement in the coloration efficiency (∼347 cm2/C) of V2O5 film. Modification with rGO resulted in an outstanding improvement in the electrochemical redox stability of V2O5 up to 5000 CV cycles with minimum deterioration in the curve area. The formation of nanorod structure was the prime factor for better ion diffusion and thereby facilitating enhanced performance.

Reversible Modulation of Plasmonic Coupling of Gold Nanoparticles Confined within Swellable Polymer Colloidal Spheres.

Dynamic optical modulation in response to stimuli provides exciting opportunities for designing novel sensing, actuating, and authentication devices. Here, we demonstrate that the reversible swelling and deswelling of crosslinked polymer colloidal spheres in response to pH and temperature changes can be utilized to drive the assembly and disassembly of the embedded gold nanoparticles (AuNPs), inducing their plasmonic coupling and decoupling and, correspondingly, color changes. The multi-responsive colloids are created by depositing a monolayer of AuNPs on the surface of resorcinol-formaldehyde (RF) nanospheres, then overcoating them with an additional RF layer, followed by a seeded growth process to enlarge the AuNPs and reduce their interparticle separation to induce significant plasmonic coupling. This configuration facilitates dynamic modulation of plasmonic coupling through the reversible swelling/deswelling of the polymer spheres in response to pH and temperature changes. The rapid and repeatable transitions between coupled and decoupled plasmonic states of AuNPs enable reversible color switching when the polymer spheres are in colloidal form or embedded in hydrogel substrates. Furthermore, leveraging the photothermal effect and stimuli-responsive plasmonic coupling of the embedded AuNPs enables the construction of hybrid hydrogel films featuring switchable anticounterfeiting patterns, showcasing the versatility and potential of this multi-stimuli-responsive plasmonic system.

Wavelength-selective, time-resolved, and visible-light-responsive multicolor switching systems for multistate dynamic information encryption

Visible-light-responsive photoreversible multi-color switching systems (PMCSSs) are attractive to meet the advanced demands in dynamic information encryption. Particularly, PMCSSs with wavelength-selective and time-resolved color switching are highly important but underexplored. Here, a new strategy is proposed to realize wavelength-selective, time-resolved, and visible-light-responsive PMCSSs by integrating acetamide ligand-capping CdS (CdS-NH2) nanoparticles and various redox dyes in solid films for multistate dynamic information encryption. The –NH2 groups of surface-bounded CH3CONH2 act as sacrificial electron donors for scavenging photogenerated holes to endow the CdS-NH2 nanoparticles high photoreductive ability and activity in a broad visible light range from 400 to 515 nm, thus enabling the long-waited wavelength-selective multicolor switching via coupling the wavelength-dependent photoreductivity of CdS-NH2 nanoparticles and the discoloration kinetics of redox dyes, such as methylene blue (MB) and phenosafranine (PS). Moreover, the time-dependent color switching during recoloration process of the color switching system can be modulated by tuning the oxidation kinetics of MB and methylene green (MG), enabling time-resolved dynamic imaging characteristics. Based on the unusual properties of the PMCSSs, a kind of wavelength-selective and time-resolved codes are designed for advanced dynamic information encryption. This work provides new guidance for developing of new PMCSSs for information encryption with high security requirements.

Naphthalene-embedded spiropyran derivative-A type of conjugated expanded material with solid-state photochromic properties and tunable color switching range

Due to the limited free volume in the solid state, spiropyrans generally exhibit photochromic properties in solution or mixed thin films. However, few spiropyrans can display the photoisomerization process in the solid state. One conventional solution for solid-state photochromism is to embed the spiropyran on polymer chains or introduce bulky groups to create an efficient free volume in the solid state. In this article, we attempt to introduce large conjugated fragments on the spiropyran backbone to construct a donor-acceptor (D-A) building block that not only possesses an enlarged π-electron system with enhanced electronic delocalization capability but also exhibits an improved free volume for efficient solid-state photoisomerization. Through this strategy, we have successfully embedded the naphthalene ring on the spiropyran backbone to obtain a novel D-A type conjugated building block, SP-Naph, which exhibits excellent solid-state photochromic performance and reversibility. Furthermore, the D-A structure of SP-Naph significantly tuned its photochromic color-switching range to blue. Consequently, SP-Naph was successfully applied in optical printing and invisible inks. The excellent solid photochromic properties make it exhibit remarkable photochromic effects, indicating significant potential for optical printing and anti-counterfeiting applications.