Changes In Transmission Research Articles

Revolutionizing Dual-Band Modulation and Superior Cycling Stability in GDQDs-Doped WO3 Electrochromic Films for Advanced Smart Window Applications.

Dual-band tungsten oxide (WO3) electrochromic films are extensively investigated, yet challenges persist regarding complex fabrication processesand limited cyclic stability. In this paper, a novel approach to prepare graphdiyne quantum dots (GDQDs) doped WO3 films with a hexagonal crystal structure, is presented. Structural characterization reveals that the GDQDs/WO3 possesses a coral-like, loose structure with high crystallinity due to the synergistic modulation of morphology and crystallinity. Electrochemical tests confirm that this unique structure provides abundant multi-active sites and efficient electrolyte ion channels, which facilitate the ion insertion/extraction to promote the electrochromic process. The GDQDs/WO3 films exhabit impressive electrochromic performance, with rapid swithing (12.6/8.4 s for bleaching/coloration), high coloring efficiency (104.78 cm2C-1 at 1100nm), and independent dual-band transmittance changes (ΔT， with ΔT633nm = 64.54%, ΔT1100nm = 83.52% and ΔT1600nm = 79.80%), and exceptional stability (remained 95.1% modulation range after 20 000 cycles). The unique characteristics of GDQDs lead to the formation of a built-in electric field via charge transfer, which optimizes and enriches the energy level structure of WO3. This solution not only advances the development of electrochromic technology, but also opens the door for future innovative applications of smart materials.

Electrically Tuning Quasi‐Bound States in the Continuum with Hybrid Graphene‐Silicon Metasurfaces

AbstractMetasurfaces have become one of the most prominent research topics in the field of optics owing to their unprecedented properties and novel applications on an ultrathin platform. By combining graphene with metasurfaces, electrical tunable functions can be achieved with fast tuning speed, large modulation depth, and broad tuning range. However, the tuning efficiency of hybrid graphene metasurfaces within the short‐wavelength infrared (SWIR) spectrum is typically low because of the small resonance wavelength shift in this wavelength range. In this work, through the integration of graphene and silicon metasurfaces that support quasi‐bound states in the continuum (quasi‐BIC), the critical coupling as well as transmittance spectrum tuning is experimentally demonstrated. The spectrum tuning is substantial even with less than 30 nm resonance wavelength shift thanks to the high quality factor of quasi‐BIC metasurfaces. The tunable transmittance spectrum is measured using Fourier transform infrared spectroscopy (FTIR) with a modified reflective lens to improve the accuracy, and the electrical tuning is realized utilizing the “cut‐and‐stick” method of ion gel. At the wavelength of 3.0 µm, the measured transmittance change (ΔT = Tmax − Tmin) and modulation depth (ΔT/Tmax) can reach 22.2% and 28.9%, respectively, under a small bias voltage ranging from −2 to +2 V. This work demonstrates an effective way of tuning metasurfaces within the SWIR spectrum, which has potential applications in optical modulation, reconfigurable photonic devices, and optical communications.

The Effect of H+ Fluence Irradiation on the Optical, Structural, and Morphological Properties of ZnO Thin Films.

Polycrystalline zinc oxide (ZnO) thin films were deposited on soda-lime glass substrates using the chemical spray pyrolysis method at 450 °C. The samples were irradiated with 8 keV H+ ions at three different fluences using a Colutron ion gun. The effects of the irradiation on the structural, morphological, and optical properties were studied with different techniques, including Rutherford Backscattering Spectrometry (RBS), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Ultraviolet and Visible Spectroscopy (UV-Vis). The results show that ion irradiation enhances crystallinity, narrowing the optical band gap. The changes in transmittance are related to defect formation within the material, which acts as light absorption and re-emission centers. A shifting of the film's preferred growth orientation to the c-axis and changing the grain morphology and size distribution was detected. We observed an increase in the lattice parameters observed after irradiation, suggesting an expansion of the crystalline structure due to ions incorporation and defects within the ZnO crystal lattice. The morphological study shows an increase in the average size of the large particles after irradiation. This change is attributed to the emergence of defects and nucleation centers during irradiation. The average size of small particles remained relatively constant after irradiation, suggesting that small particles are more stable and less susceptible to external influences, resulting in fewer changes due to irradiation.

Solid‐State Photochromic Transparent Photovoltaics with Bisthienylethene‐Based Molecules

Photochromic transparent photovoltaic is a promising candidate for developing smart windows in the building‐integrated photovoltaic field. However, most reported photochromic solar cells must employ liquid electrolyte in the device to achieve the photochromic function. Herein, solid‐state photochromic semitransparent organic photovoltaics (ST‐OPVs) based on a photochromic molecule with bisthienylethene (BTE) unit are reported. ST‐OPVs show a transmittance change of up to 6.10% under light irradiation, demonstrating a power conversion efficiency (PCE) of 5.21% and an average visible transmission of over 50%. The coloration–decoloration process is reversible under UV irradiation and thermal annealing. After five coloration–decoloration cycles, the photochromic ST‐OPVs can maintain 66.6% of the initial PCE. This work presents a promising application of photochromic molecules in ST‐OPVs, providing a feasible strategy for photochromic photovoltaics.

Experimental Evaluation Study of the Comfort and Energy Performance of Suspended Particle Device Smart Windows in a Residential Building: Achieving Optimal Control during the Cooling Season

In contrast to traditional windows, smart windows dynamically affect indoor visual and thermal environments through Visible light transmittance (VT) and Solar heat gain coefficient (SHGC) changes. Therefore, for enhancing smart window application effects, it is necessary to analyze comprehensively the impacts of smart window tinting on indoor visual and thermal environments, and to establish appropriate tinting control methods. This study aimed to determine optimal smart window control strategies for residential buildings during the cooling season by evaluating visual and thermal comfort and energy performance in an actual building equipped with SPD smart windows. An experimental building was located in Sejong, South Korea (36.5°N latitude, 127.3°E longitude; temperate climate zone), and the measurements were conducted from July to August 2023 to compare glare, indoor daylight illuminance, thermal comfort, and cooling and lighting energy between typical and smart windows. And, optimal control methods were proposed from general comfort and energy performance perspectives. The measurements indicated that it was difficult to satisfy all aspects of the visual and thermal environment, and comprehensively it was recommended to employing “always tinting” on summer. However, on a clear day, jointly applying smart windows and lighting dimming control and controlling automatically based on indoor daylight illuminance levels were found to be the most effective as it not only secured visual comfort performance but also reduced lighting energy consumption.

A Novel Technique for Monitoring Carbonate and Scale Precipitation Using a Batch-Process-Based Hetero-Core Fiber Optic Sensor.

Techniques for monitoring calcium carbonate and silica deposits (scale) in geothermal power plants and hot spring facilities using fiber optic sensors have already been reported. These sensors continuously measure changes in light transmittance with a detector and, when applied to field tests, require the installation of a power supply and sensor monitoring equipment. However, on some sites, a power supply may not be available, or a specialist skilled in handling scale sensors is required. To overcome this problem, we have developed a method for evaluating scale formation that is based on a batch process that can be used by anyone. In brief, this method involves depositing scale on a section of the optical fiber sensor and then fusing this section to the optical fiber and measuring it. Using this sensor, a technician in the field can simply place the sensor in the desired location, collect the samples at any given time, and send them to the laboratory to measure their transmittance. This simple and easy method was achieved by using a hetero-core type of fiber optic. This evaluation method can measure with the same sensitivity as conventional real-time methods, while its transmittance response for the sensor corresponds to the saturation index (SI) changes in the scale components in the solution due to increases in temperature and concentration. In the field of carbon dioxide capture and storage (CCS), this evaluation method can be used to quantitatively measure the formation of carbonate minerals, and it can also be used as an indicator for determining the conditions for CO2 mineral fixation, as well as in experiments using batch-type autoclaves in laboratory testing. It is also expected to be used in geothermal power plants as a method for evaluating scale formation, such as that of amorphous silica, and to protect against agents that hinder stable operation.

Nano-Silica-Based Double-Layer Antireflective Coatings with Mildew Resistance and Moisture Resistance for KDP Crystals.

Sol-gel nano-silica antireflective (AR) coatings with moisture resistance are widely used for optical elements, such as potassium dihydrogen phosphate (KDP) crystals, but their mildew resistance is often disregarded. This work reports a double-layer AR coating with moisture resistance and mildew resistance for KDP crystals. A polydimethylsiloxane-modified dense silica coating and a quaternary ammonium salt (QAS) modified nanoporous silica coating are selected as the bottom layer and top layer, which effectively serve as a moisture barrier and an antireflection layer, respectively. The coated KDP crystal shows excellent antireflection properties with a maximum transmittance of 99.1% at 532nm. Perfluorooctyltriethoxysilane vapor treatment is performed further to improve the resistance to moisture and mildew. The resultant double-layer coating exhibits superior moisture resistance with almost no change in optical transmittance after a 3-month exposure to a high-humidity environment. The introduction of QAS and hydrophobicity in the top layer provides exceptional resistance against mildew, achieving an antimicrobial rate of 99.9% against E. coli and A. flavus. Moreover, the laser-induced damage threshold reaches 17.0 J cm-2 (355nm, 4.5ns). This work imparts moisture resistance and mildew resistance to AR coatings, providing valuable insights for designing multifunctional AR coatings on optical components.

Experimental study on optical properties of various paraffin-based PCM glazing unit and radiative transfer model optimization

Integrating phase change material (PCM) into glazing units can lead to the ability of dynamic response to solar radiation and enhance thermal mass. In order to clarify the optical performance of phase change material glazing unit (PCMGU) during the dynamic response stage, this study analyzes the variations of transmittance and reflectance of PCMGUs filled with different paraffins during phase change process, by using a spectrophotometer and a temperature measurement device. Additionally, the impact of the paraffin cooling rate on this process was also examined. The experimental results indicate that: (1) During the solid-liquid phase change process, the curve of PCMGU transmittance and reflectance versus paraffin temperature exhibits a significant linear characteristic, with 75–93 % of transmittance and reflectance changes appearing during this stage; (2) Adjusting the paraffin cooling rate does not alter this linear characteristic; (3) Approximately 19 % and 36 % of PCMGU transmittance and reflectance changes occur during the solid-solid phase change process, respectively. Finally, based on the experimental patterns, the radiative transfer model for PCMGU was optimized, reducing its calculation error to a range of 0.17–0.92 times that of previous models (in terms of root mean square error).

Enhancing Multilayer Glass Transmittance through Particle Swarm Optimization: An Experimental Approach

Abstract. This study focuses on enhancing the solar transmittance of multilayer glass in buildings located in cold northern regions to improve natural lighting efficiency and maintain indoor warmth in harsh climates. The Particle Swarm Optimization (PSO) algorithm is utilized to optimize the glass layer thickness, and an optical model is constructed to calculate the light transmittance of the multilayer glass. Through simulations and experimental analysis, the impact of different glass thickness combinations on overall transmittance is investigated. The study examines the optical properties of gradient glass and calculates changes in light transmittance under varying thickness combinations using MATLAB software. The PSO algorithm is applied for global optimization to identify the glass thickness combination that maximizes light transmittance within the specific visible light range (400nm-800nm). The experimental results, including spectral energy distribution before and after sunlight transmission, validate the accuracy of the theoretical model. The findings demonstrate that the optimized glass thickness combination significantly improves solar transmittance, especially within the visible light band, contributing to more energy-efficient and comfortable building environments in cold regions. Additionally, the potential of the PSO algorithm in global search and local convergence is analyzed, suggesting future research directions to further enhance optimization through dynamic adjustments or combining with other algorithms.

Enhancing Multilayer Glass Transmittance through Particle Swarm Optimization: An Experimental Approach

Abstract. This study focuses on enhancing the solar transmittance of multilayer glass in buildings located in cold northern regions to improve natural lighting efficiency and maintain indoor warmth in harsh climates. The Particle Swarm Optimization (PSO) algorithm is utilized to optimize the glass layer thickness, and an optical model is constructed to calculate the light transmittance of the multilayer glass. Through simulations and experimental analysis, the impact of different glass thickness combinations on overall transmittance is investigated. The study examines the optical properties of gradient glass and calculates changes in light transmittance under varying thickness combinations using MATLAB software. The PSO algorithm is applied for global optimization to identify the glass thickness combination that maximizes light transmittance within the specific visible light range (400nm-800nm). The experimental results, including spectral energy distribution before and after sunlight transmission, validate the accuracy of the theoretical model. The findings demonstrate that the optimized glass thickness combination significantly improves solar transmittance, especially within the visible light band, contributing to more energy-efficient and comfortable building environments in cold regions. Additionally, the potential of the PSO algorithm in global search and local convergence is analyzed, suggesting future research directions to further enhance optimization through dynamic adjustments or combining with other algorithms.

Glass catfish inspired subaquatic abrasion-resistant anti-fouling window fabricated by femtosecond laser electrodeposition

Abstract Transparent materials utilized as underwater optical windows are highly vulnerable to various forms of pollution or abrasion due to their intrinsic hydrophilic properties. This susceptibility is particularly pronounced in underwater environments where pollutants can impede the operation of these optical devices, significantly degrading or even compromising their optical properties. The glass catfish, known for its remarkable transparency in water, maintains surface cleanliness and clarity despite exposure to contaminants, impurities abrasion, and hydraulic pressure. Inspired by the glass catfish’s natural attributes, this study introduces a new solution named subaquatic abrasion-resistant and anti-fouling window (SAAW). Utilizing femtosecond laser ablation and electrodeposition, the SAAW is engineered by embedding fine metal bone structures into a transparent substrate and anti-fouling sliding layer, akin to the sturdy bones among catfish’s body. This approach significantly bolsters the window’s abrasion resistance and anti-fouling performance while maintaining high light transmittance. The sliding layer on the SAAW’s surface remarkably reduces the friction of various liquids, which is the reason that SAAW owns the great anti-fouling property. The SAAW demonstrates outstanding optical clarity even after enduring hundreds of sandpaper abrasions, attributing to the fine metal bone structures bearing all external forces and protecting the sliding layer of SAAW. Furthermore, it exhibits exceptional resistance to biological adhesion and underwater pressure. In a green algae environment, the window remains clean with minimal change in transmittance over one month. Moreover, it retains its wettability and anti-fouling properties when subjected to a depth of 30 m of underwater pressure for 30 d. Hence, the SAAW prepared by femtosecond laser ablation and electrodeposition presents a promising strategy for developing stable optical windows in liquid environments.

Change of crystallinity and optical transmittance of K2Ni(SO4)2·6H2O single crystal by heat treatment

Potassium nickel sulfate hexahydrate (KNISH) was prepared and grown as single crystal from the supersaturated aqueous solution at 309 K using slow evaporation method. Thermal measurements were achieved for the prepared crystal. The dehydration process, structural phase transitions and melting point of the obtained material were detected. Crystal structure and optical transmittance of KNISH crystal were studied through heat treatment. At 370 K, the dehydration process started to convert KNISH to the anhydrous phase KNIS and the crystallinity decreased gradually until the material became totally amorphous at 383 K. The anhydrous KNIS stayed at the amorphous state from 383 K to 629 K where it transformed again to the crystalline state with different structure. The heat treatment under dehydration temperature did not affect the efficiency of KNISH crystal for using as ultraviolet light filter and sensor. Above dehydration temperature, the obtained anhydrous phase KNIS is not suitable for these applications.

Limitations and characteristics of converted industrial acrylic sheet into an in vitro platform using CO2 laser

The recent US FDA Modernization Act 2.0 has intensified interest in microfluidic-based in vitro systems for preclinical research. However, the high costs of conventional microfabrication methods and commercial devices present significant barriers, particularly in developing countries. This study addresses these challenges by exploring the use of industrial-grade acrylic sheets and a conventional CO2 laser for cost-effective microfabrication. The research investigates the effects of laser parameters—specifically nozzle speed and power—on the dimensions and quality of microchannels, surface roughness, and bonding strength. Results indicate that increased nozzle speed reduces kerf width and enhances microchannel quality, whereas high laser power (∼52 watts) induces bubbling at the edges. A simple acetone and ethanol mixture was found to provide optimal bonding strength without altering the acrylic’s molecular structure. UV spectrophotometry revealed minimal changes (∼6 %) in visible light transmittance due to bonding conditions, while FTIR analysis showed no residuals that could potentially cause cytotoxicity. Despite variations in surface roughness resulting from the etching process, cell viability remained unaffected. The surfaces supported effective cell culture for lung (A549), neuron (SH-SY5Y), and liver (HepG2) cell lines. This approach presents a practical and cost-effective solution for developing in vitro platforms, making it an accessible option for research and academic applications.

(Invited) Development of Fiber-Optic Hydrogen Sensor Using Platinum-Supported Tungsten Trioxide-Silica Composite Film

A fiber-optic hydrogen gas sensor using a platinum-supported tungsten oxide-silica composite film was fabricated. This sensor utilizes the absorption of the evanescent field interaction in the hydrogen sensitive clad which was composed of WO3 and SiO2, coated on a silica core with sol-gel process. As a first step, transmission spectra of sensing film itself were measured. The transmittance of the sensitive film decreased in the range of wavelengths above about 500 nm after exposure to pure hydrogen, and the change in transmittance at 1300 nm was greater than that at 850 nm. Then, fiber optic sensor device was fabricated, and the amount of propagating light was measured. In the case of using the light source with a wavelength of 1300 nm, the sensitivity with respect to the hydrogen response was nearly twice and the response speed was faster, compared with those at 850 nm.

Dual-donor D-A-D types electrochromic conjugated polymers employed quinoxaline as the acceptor: Synthesis, electrochemistry, and electrochromism

In this work, two donor-acceptor-donor (D-A-D) type electrochromic conjugated polymers were prepared upon electrochemical oxidation through their precursors employed dual-thiophene derivatives as the donor units and quinoxaline as the acceptor unit. The effects of different donor substituents on the polymers’ electrochemical and electrochromic properties were carefully examined. Owing to the introduction of stronger electron donor ability of 3,4-ethylenedioxythiophene (EDOT), P(Q-T-E) demonstrated good coplanarity and dense surface morphology, outstanding redox activity and stability (retained 97 % after 1000 cycles), low optical band gap (1.45 eV). P(Q-T-T) exhibited excellent electrochromic performance of above 30 % transmittance changes in both the NIR region and the visible region, as fast as 0.75 s response time, and high coloration efficiency value of 212.8 cm2 C−1. The Dual-donor strategy may provide a new research idea to achieve high-performance electrochromic D-A-D conjugated polymers.

Study on the elimination characteristics of smoke particles with different materials using electric agglomeration technology

ABSTRACT Fire smoke, consisting of solid particles and liquid droplets, poses risks of asphyxiation, poisoning, making it a significant contributor to fire-related fatalities and environmental pollution. The exploration of effective smoke control methods represents a vital approach to reducing the threat of fire smoke to public health and safety. This study aims to determine the characteristics of elimination for the fire smoke generated from burning four typical materials, thereby validating the universality of electric agglomeration smoke elimination technology. The results indicate that the elimination efficiency of electric agglomeration varies with the material type of the smoke. The rate of change in smoke transmittance from fast to slow is: polyvinyl chloride (PVC), polystyrene (PS), wood, and styrene butadiene rubber (SBR), respectively. With an external potential of 4 kV, PVC smoke reaches the safe threshold after 12.1 s, while SBR smoke achieves it in just 4.9 s. Analysis of the microscopic morphology of agglomerates with scanning electron microscopy (SEM) reveals that particle size distribution is an important factor affecting electric agglomeration elimination. This is because larger initial particles carry a greater charge, enabling the formation of larger agglomerates for more efficient removal. This study provides theoretical guidance for the practical application of electric agglomeration in eliminating smoke particles.

Structural and electrochromic property control of WO3 films through fine-tuning of film-forming parameters

Abstract Tungsten trioxide (WO3) films, extensively investigated for their remarkable electrochromic properties, have proven to be highly versatile in numerous applications. However, the challenge of achieving large-scale WO3 films with substantial dimensions and volumes remains a critical obstacle for industrial-scale production. Among the available techniques, magnetron sputtering stands out as the most efficient and straightforward method for the industrial preparation of WO3 films. In this comprehensive study, we meticulously explored the impact of various process parameters in magnetron sputtering on the film formation properties. By employing a controlled variable approach, we systematically investigated the influence of gas flow (Ar), sputtering pressure, power, and time. Our meticulous observations revealed that each parameter exerted distinct effects on the intricate film formation process. Careful analysis of the final dataset unequivocally demonstrated that when the sputtering conditions were meticulously optimized, the resulting films exhibited an extraordinary maximum transmittance change of 85% at a specific wavelength of 0.6 μm. Furthermore, these films showcased rapid coloring and bleaching response times, clocking in at an impressive 15 and 20 s, respectively, without any significant degradation even after undergoing 5,000 cycles. These groundbreaking findings provide invaluable insights into the intricate film formation process associated with magnetron-sputtered WO3.

Plasma-enhanced atomic layer deposition as a technique for controlling the composition and properties of indium-based transparent conductive oxides

Indium oxide and doped indium oxide films were successfully grown utilizing a plasma-enhanced atomic layer deposition supercycling process, which was found to be an effective means of controlling films’ composition and, hence, their properties. Using trimethylindium and oxygen plasma as an indium precursor and a co-reactant, respectively, a growth rate of approximately 1.26 Å per cycle was obtained based on thickness measurements by spectroscopic ellipsometry. Three distinct dopants, Sn, Ti, and Mo, have been incorporated into indium oxide. The effects of dopant type, cycle ratio of dopant to indium oxide, and thermal annealing on the structural, electrical, and optical properties were studied. The deposited films consisted of polycrystalline columnar grains perpendicular to the substrate with a cubic bixbyite structure and [111] as the favored growth direction. Thermal annealing had a significant effect on the film characteristics, resulting in an order of magnitude reduction in resistivity, as well as changes in transmittance in the near-infrared (NIR) and ultraviolet (UV) regions. The lowest resistivities achieved for Sn-doped, Ti-doped, and Mo-doped were 2.8 × 10−4, 4.2 × 10−4, and 6.1 × 10−4 Ω cm, respectively. The changes are attributed to dopant activation, as the UV shift between the differently doped samples may be linked to the Moss–Burstein effect and the NIR behavior can be explained by an increase in charge carrier density, as predicted by the Drude model. The three dopants primarily provide a trade-off between electrical resistance and NIR transparency. Mo-doped films exhibited the highest near-infrared transparency, while Sn-doped films offered the lowest sheet resistance.

High-contrast electrochromic coatings and devices for health assurance, visual comfort and energy-saving in buildings

High-contrast electrochromic coatings and devices reduce the ultraviolet-radiation from sunlight, ensure human health and visual comfort, save the electricity consumption of the heater in winter, and save electricity consumption of air conditioners in summer. Anodically coloring polymer coatings (P(CDBP), P(CDBP-co-BTPH), P(CDBP-co-TFU), P(CDBP-co-CDT) and P(CDBP-co-CDTK)) based on 4,4′-bis(carbazol-9-yl)-2,2′-dimethylbiphenyl (CDBP) and four different dithiophene derivatives (2,2′-bithiophene (BTPH), 2-(2-thienyl)furan (TFU), 4H-cyclopenta[2,1-b:3,4-b’]dithiophene (CDT), and cyclopentadithiophene ketone (CDTK)) are polymerized electrochemically on ITO electrode. The P(CDBP-co-BTPH) electrochromic coating has high transmittance change (ΔT = 71.1 %) and coloration efficiency (160.6 cm2 C−1). P(CDBP-co-BTPH) film reveals yellow-gray and dark blue in neutral and oxidation states, respectively. Electrochromic energy saving devices (ECDs) are assembled using P(CDBP), P(CDBP-co-BTPH), P(CDBP-co-TFU), P(CDBP-co-CDT) and P(CDBP-co-CDTK) films as the anodic layers and poly(3,4-(2,2-dimethylpropylenedioxy)thiophene) (PPD-M2) film as the cathodic layer. P(CDBP-co-BTPH)/PPD-M2 ECD shows a high transmittance change (ΔT = 30.3 %) and a rapid response time (≤0.3 s). Moreover, P(CDBP-co-BTPH)/PPD-M2 ECD also has sufficient optical memory and redox cycling stability. These findings provide us new insights for the useful design of polymer coatings in rapid switching electrochromic energy-saving devices and switchable architectural windows.

Achieving ultrahigh electrochromic stability of triarylamine-based polymers by the design of five electroactive nitrogen centers

A shortage of long-term stability of electrochromic materials has been hindering their practical application. A series of novel polyamides (PAs) (4) with five electroactive nitrogen atoms within triphenylamine (TPA)-containing structures was synthesized via phosphorylation polyamidation. Polyamide 4b exhibited highly integrated electrochromic performances, including multiple color changes, high contrast of optical transmittance change, and the highest electrochromic stability (only 11.2 and 9.6 % decay of its coloration efficiency (CE) at 450 nm after 50000 and 16000 switching cycles, respectively) compared to all other triarylamine-based polymers to date. This record-high electrochromic cycling is attributed to the enhanced stability of polaron, which was studied through the electron-donating or electron-withdrawing effect of substituents and the resonance effect of electron delocalization over the electroactive nitrogen centers. Importantly, our core design of five electroactive nitrogen centers with electron-donating methoxy groups is the key factor to increase stability of polaron in the resulting polymers 4. More electroactive nitrogen centers are able to create a weaker electronic coupling due to a charge of cation radical dispersed by resonance successfully in-between the different redox states, which is evidenced clearly by the observed longer wavelength absorption in the NIR region. Our research confirms that the key to determining polaron stability is the resonance by the electrons delocalized over all the redox centers, rather than the electronic coupling between the different redox centers. And the resonance leads to increasing electrochromic stability of the polymer.