The study of infrared low-emissivity thermal photonic materials is of profound significance in advancing thermal management and infrared stealth technologies. By systematically reviewing existing literature, we delve into the physical mechanisms, fabrication methods, and performance characteristics of these materials, highlighting their ability to suppress thermal radiation and block heat transfer. Notably, materials such as metals, conductive metal oxides, nanomaterials, phase-change materials, conductive polymers, and graphene demonstrate significant advantages in reducing emissivity and achieving dynamic infrared emissivity control. These materials have promising applications in fields like building thermal management, personal thermal management, and infrared camouflage. The significance of our study lies in its comprehensive exploration of current advancements in infrared low-emissivity materials, which are critical for enhancing energy efficiency and sustainability. By reducing infrared emissivity, these materials can manage thermal radiation in various environmental conditions and application scenarios. Additionally, their potential in military applications for infrared stealth further underscores their significance. We also identify key future directions, including the development of ultra-low emissivity materials, environmental stability improvement of these materials, production enhancement for widespread application, and exploration of synergies between thermal radiation control and traditional thermal management techniques. These advancements will be crucial to addressing global challenges related to energy efficiency, climate change, and security.

Significant progress has been made in the development of infrared low-emissivity materials. Metals such as aluminum, copper, silver, and conductive metal oxides like indium tin oxide demonstrate high infrared reflectivity due to their unique dielectric properties (Fig. 1). Recent studies have explored various structures including multilayer films, organic polymers, metal-polymer composites, nanomaterials, and graphene to enhance the efficiency of thermal radiation control and achieve multi-target stealth and encryption. For instance, Fan et al. synthesized an Al-reduced graphene oxide composite that improved aluminum’s anti-oxidation properties and achieved low infrared emissivity of 0.62. Similarly, Zhang et al. developed an ultra-low infrared emissivity coating by employing aluminum flakes and epoxy resin, which maintained its properties even after prolonged exposure to salt water. Fang et al. introduced a metamaterial based on gold nanoparticles assembled into hollow pillars, demonstrating selective visible light absorption and low infrared emissivity [Fig. 2(a)]. Luo et al. created a spectrally selective absorbing layer by utilizing polydopamine coated with gold and germanium, thereby achieving high absorption in the UV-visible-NIR range and low emissivity in the mid-infrared range [Fig. 2(b)]. Peng et al. developed a colorful infrared low emission paint with a double-layer coating structure by adopting aluminum flakes and inorganic pigment particles, maintaining infrared emissivity of about 20% and exhibiting rich colors [Fig. 2(c)]. To achieve visible light transparency and maintain low infrared emissivity, researchers have developed dielectric-metal-dielectric (DMD) multilayer structures. For example, Wang et al. optimized MgF₂/Ag/MgF₂ structures to achieve average emissivity of around 30% in the infrared range and 80% transparency in the visible range [Fig. 2(d)]. These advancements are summarized in Fig. 2, which illustrates various metal-based low-emissivity materials and their applications. Polyethylene and other polymeric materials with infrared transparency have also shown promise. Hsu et al. developed nanoporous PE textiles that scatter visible light and maintain high infrared transmittance, suitable for personal cooling applications [Fig. 3(a)]. Cai et al. further enhanced these textiles by incorporating inorganic pigment particles to achieve colorful infrared transparent fabrics [Figs. 3(b) and 3(c)]. Additionally, MXene-modified nanoporous PE textiles demonstrate significant potential in passive and active personal heating applications. Flexible and stretchable materials like those based on SEBS polymers have been adopted to create low-emissivity films that can dynamically adjust their infrared reflectivity via mechanical stretching [Fig. 3(d)]. Fig. 3 presents key developments in infrared transparent polymeric materials and conductive metal oxide-based low-emissivity materials. Conductive metal oxides such as ITO and AZO feature high visible light transmittance and low infrared emissivity, making them ideal for applications like smart windows. Bianchi et al. optimized an ITO/Ag/ITO structure to achieve approximately 80% infrared reflectivity and high visible light transmittance [Fig. 3(e)]. Wang et al. developed a structure combining VO₂ nanocomposite coatings with ITO layers, demonstrating variable emissivity controlled by temperature. Advances in nanomaterials, including MXenes and nanocomposites, have provided new pathways for low-emissivity control. For example, Shi et al. created a textile by employing MXene-modified nanoporous polyethylene, achieving mid-infrared emissivity of 0.176 [Fig. 4(a)]. Ma et al. developed lightweight, dual-functional nanocomposite foams with microporous structures, achieving significant reductions in radiation temperature and effective infrared stealth [Fig. 4(b)]. Hassan et al. combined highly crystalline Ti₃C₂T_x MXene with carbon nanotube (CNT) thin films to create Janus thin films, which have infrared emissivity of up to 93% in the cooling mode and as low as 0.09 in the insulation mode [Fig. 4(c)]. Fig. 4 shows various nanomaterial-based low-emissivity materials. Dynamic infrared emissivity control has been a recent research hotspot. Metals and metal oxides have been utilized for dynamic thermal control via mechanisms like mechanical stretching and electrochemical deposition. Xu et al. developed an adaptive infrared reflecting system by utilizing a dielectric elastomer membrane coated with aluminum, which changes from wrinkled shapes to flat shapes under mechanical strain and then alters its infrared reflectivity [Fig. 5(a)]. Leung et al. created a dynamic thermoregulatory material inspired by squid skin, with copper nanostructures embedded in a polymer employed to switch between reflection and transmission of infrared radiation via mechanical stretching [Fig. 5(b)]. Li et al. developed a device based on reversible silver electrodeposition on a platinum nanofilm, enabling adaptive thermal camouflage by switching between high and low emissivity states [Fig. 5(c)]. Mandal et al. introduced a visible-to-infrared broadband electrochromic material based on lithium titanate (Li₄Ti₅O₁₂), significantly changing the emissivity by lithium-ion intercalation [Fig. 5(d)]. Zhang et al. adopted amorphous and crystalline WO₃ electrochromic thin films to create a device with substantial infrared emissivity modulation [Fig. 5(e)]. Figs. 5 and 6 illustrate various dynamic low-emissivity thermal photonic materials and their control mechanisms. Infrared low-emissivity materials have diverse applications, particularly in building thermal management, personal heat management, and infrared thermal camouflage. In buildings, low-emissivity coatings on glass and other materials can significantly reduce energy consumption for heating and cooling by minimizing heat radiation. For instance, Bianchi et al. developed an ITO/Ag/ITO coating with high near-infrared reflectivity and visible light transmittance, which is ideal for energy-efficient windows. Similarly, Peng et al. created colorful low-emissivity films that can be leveraged to build walls to enhance thermal insulation and save energy [Fig. 7(a)]. Personal heat management benefits from advanced textiles incorporating low-emissivity materials [Fig. 7(b)]. Hsu et al. designed nanoporous PE textiles that maintain high infrared transmittance for cooling, while Cai et al. developed dual-mode textiles capable of both heating and cooling by adjusting the orientation of high and low-emissivity layers [Fig. 7(c)]. These textiles can improve thermal comfort and reduce the need for HVAC systems. In infrared thermal camouflage, materials such as those developed by Hu et al. with the combination of silver particles and modified graphene can significantly lower surface temperature and evade infrared detection. Ma et al. created lightweight nanocomposite foams that enhance infrared stealth by reducing radiation temperature [Fig. 7(d)]. These applications demonstrate the potential of low-emissivity materials to contribute to energy efficiency, thermal management, and stealth technologies (Fig. 7).

Infrared low-emissivity thermal photonic materials play a crucial role in thermal radiation control, enabling effective insulation and infrared stealth. Our study highlights significant advancements in metal-based, polymeric, and nanomaterial low-emissivity materials, as well as dynamic control methods by employing metals, metal oxides, phase change materials, conductive polymers, and graphene. These materials demonstrate substantial potential in building thermal management, personal heat management, and infrared thermal camouflage. Future research should focus on developing ultra-low emissivity materials with enhanced environmental stability to ensure their performance in extreme conditions. Additionally, scalable production methods should be developed to facilitate the widespread application of these materials in various sectors. Exploring their potential in such emerging fields as smart wearable devices and energy-efficient technologies will further expand their influence. Meanwhile, collaborative applications of thermal radiation control and traditional thermal control are developed to achieve efficient, integrated, and intelligent thermal control technology. Generally, continued advancements in infrared low-emissivity materials will contribute significantly to energy efficiency, thermal management, and stealth technologies, thereby making progress toward sustainable and innovative solutions for a wide range of applications. The development of materials with even lower emissivity, improved environmental stability, and scalable production methods will be critical in achieving these goals. Researchers should also explore the integration of these materials into new and emerging applications, such as smart textiles and energy-efficient building materials, to maximize their influence on sustainability and technological innovation.