Thermoelectric Nanomaterials for Energy Harvesting in Electronics

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In the pursuit of smaller, more powerful electronics, energy efficiency has become a driving force behind innovation. As devices become more compact and expand their performance capabilities, they also generate more heat. Traditionally viewed as a waste byproduct, heat is now being transformed into energy through the integration of thermoelectric technologies in electronic devices. At the forefront of this transformation are thermoelectric nanomaterials—minute structures that are enabling new applications in wearables, remote sensors, and autonomous systems. As we explore their capabilities in this blog, we will uncover how thermoelectric nanomaterials are paving the way for smarter, more sustainable electronics.

The Thermoelectric Effect: Converting Heat into Electricity

Thermoelectric devices convert heat directly into electricity through a phenomenon known as the thermoelectric effect. This effect is governed by three interrelated mechanisms:

• Seebeck effect: A voltage is generated across a material when a temperature difference exists.
• Peltier effect: Heat is absorbed or released at the junction of two materials when an electric current flows.
• Thomson effect: Heat is generated or absorbed along a conductor carrying current through a temperature gradient.

Thermoelectric efficiency depends on a material’s Seebeck coefficient, electrical conductivity, and thermal conductivity. Materials with high electrical conductivity and low thermal conductivity are ideal, as they maximize electricity generation while minimizing heat loss.

While bulk materials have long been used in thermoelectric systems—from industrial heat recovery to spacecraft power supplies, portable electronics, sensors, cooling devices, and power generation systems—nanomaterials are now emerging as game changers, especially for compact and specialized applications.

Why Nanomaterials Are Game Changers

Nanomaterials behave differently from their bulk counterparts because quantum effects dominate at the nanoscale. These quantum effects allow nanomaterials to manipulate heat and electrical transport in ways that bulk materials do not. For example, nanomaterials can modulate and separate their thermal and electron transport properties, leading to high-performance thermoelectric materials.

Low-dimensional nanomaterials—such as 1D nanowires and 2D sheets—exhibit quantum confinement, where electrons are restricted in at least one dimension. This confinement creates discrete energy bands, which alter the material’s density of states in a way that boosts the Seebeck coefficient without sacrificing electrical conductivity. These nanomaterials’ discrete energy bands improve the density of states, which is a critical factor for thermoelectric performance.

On the thermal side, nanomaterials excel at selectively and effectively scattering phonons—a vibrational quasi-particle in a material related to atomic vibrations that play a role in heat transfer. This reduces the thermal conductivity of the material without affecting its electrical conductivity properties. Specialized mechanisms like Umklapp scattering in 1D materials and surface scattering or edge effects in 2D materials further enhance this property. Since thermoelectric efficiency improves as thermal conductivity decreases, these characteristics make nanomaterials particularly attractive.

Emerging Thermoelectric Nanomaterials

Thanks to advances in fabrication and epitaxial growth techniques, designers can now create a wide variety of nanomaterials tailored for thermoelectric devices. While bulk materials still dominate commercial use, nanomaterials are gaining traction in research and niche applications.

Among the most promising 1D nanomaterials are carbon nanotubes (CNTs), silicon nanotubes, bismuth telluride nanowires, and silicon-germanium nanowires. These materials combine low thermal conductivity with high electrical performance, making them ideal for compact thermoelectric devices.

When it comes to 2D materials, graphene stands out—though it must be modified due to its naturally high thermal conductivity. Other contenders include black phosphorus, transition metal dichalcogenides (TMDCs), MXenes, and layered compounds from groups 14 to 16.

Beyond standalone materials, designers are integrating nanomaterials into thin films, conductive polymers, and coatings, enhancing existing thermoelectric systems. Nanocrystals, with their uniform shapes and tunable properties, represent another frontier in tailoring thermoelectric performance.

Thermoelectric Nanomaterials in Modern Electronics Applications

Thermoelectric nanomaterials serve as the building blocks of thermoelectric generators (TEGs), which harness heat and convert it into electricity. TEGs are especially useful in powering small, wireless devices, such as remote sensors and off-grid Internet of Things (IoT) systems, where traditional power sources are impractical.

Nanomaterial-based or nanomaterial-enhanced thermoelectric devices hold great promise in a range of application areas where bulk thermoelectric devices are currently employed. This includes:

• Converting waste heat from a car’s exhaust into electricity to improve fuel efficiency
• Supporting thermal management systems for electronic devices
• Converting heat from decaying isotopes in space to power spacecraft
• Harnessing the excess heat given off by industrial processes and using the generated electricity back on-site
• Powering remote sensors in military and other remote monitoring devices that do not have access to traditional power sources
• Recovering heat back into electricity to improve energy use in portable electronics

Alongside more conventional applications, the small size and unique properties of nanomaterials also enable them to be used for more specialized applications. One example is the use of nanomaterials and nanomaterial-based thin films in flexible and wearable devices, as the materials can bend with the wearer without experiencing any drop in performance. Nanomaterial TEGs can be utilized as a power source for various self-powered wearable devices, including health monitors, fitness trackers, and other wearables that operate solely on body heat. Another exciting area is photodetection. Photodetectors based on the photothermoelectric effect—an offshoot of the Seebeck effect—generate electrical signals from absorbed light. Nanomaterial-based TEGs are well-suited to power these tiny devices, especially in remote sensing, environmental monitoring, night vision, and astronomy, where compact and self-powered systems are essential.

Conclusion

Thermoelectric nanomaterials are enabling more efficient, compact, and sustainable power solutions for modern electronics, ranging from wearable devices and IoT systems to industrial applications and space exploration. While they may not replace bulk thermoelectric materials in every application, nanomaterials are poised to play a critical role in the future of energy harvesting—especially in the growing fields of IoT, remote sensing, and self-powered electronics. As fabrication techniques continue to evolve, expect even more innovative uses for these tiny but powerful materials.