Solution‐processable semiconducting 2D nanoplates and 1D nanorods are attractive building blocks for diverse technologies, including thermoelectrics, optoelectronics, and electronics. However, transforming colloidal nanoparticles into high‐performance and flexible devices remains a challenge. For example, flexible films prepared by solution‐processed semiconducting nanocrystals are typically plagued by poor thermoelectric and electrical transport properties. Here, a highly scalable 3D conformal additive printing approach to directly convert solution‐processed 2D nanoplates and 1D nanorods into high‐performing flexible devices is reported. The flexible films printed using Sb2Te3nanoplates and subsequently sintered at 400 °C demonstrate exceptional thermoelectric power factor of 1.5 mW m−1K−2over a wide temperature range (350–550 K). By synergistically combining Sb2Te32D nanoplates with Te 1D nanorods, the power factor of the flexible film reaches an unprecedented maximum value of 2.2 mW m−1K−2at 500 K, which is significantly higher than the best reported values for p‐type flexible thermoelectric films. A fully printed flexible generator device exhibits a competitive electrical power density of 7.65 mW cm−2with a reasonably small temperature difference of 60 K. The versatile printing method for directly transforming nanoscale building blocks into functional devices paves the way for developing not only flexible energy harvesters but also a broad range of flexible/wearable electronics and sensors.
Flexible thermoelectric (TE) devices hold great promise for energy harvesting and cooling applications, with increasing significance to serve as perpetual power sources for flexible electronics and wearable devices. Despite unique and superior TE properties widely reported in nanocrystals, transforming these nanocrystals into flexible and functional forms remains a major challenge. Herein, demonstrated is a transformative 3D conformal aerosol jet printing and rapid photonic sintering process to print and sinter solution‐processed Bi2Te2.7Se0.3nanoplate inks onto virtually any flexible substrates. Within seconds of photonic sintering, the electrical conductivity of the printed film is dramatically improved from nonconductive to 2.7 × 104S m−1. The films demonstrate a room temperature power factor of 730 µW m−1K−2, which is among the highest values reported in flexible TE films. Additionally, the film shows negligible performance changes after 500 bending cycles. The highly scalable and low‐cost fabrication process paves the way for large‐scale manufacturing of flexible devices using a variety of high‐performing nanoparticle inks.
more » « less- Award ID(s):
- 1747685
- PAR ID:
- 10461219
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 29
- Issue:
- 35
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract -
Abstract Thermoelectric generators are an environmentally friendly and reliable solid‐state energy conversion technology. Flexible and low‐cost thermoelectric generators are especially suited to power flexible electronics and sensors using body heat or other ambient heat sources. Bismuth telluride (Bi2Te3) based thermoelectric materials exhibit their best performance near room temperature making them an ideal candidate to power wearable electronics and sensors using body heat. In this report, Bi2Te3thin films are deposited on a flexible polyimide substrate using low‐cost and scalable manufacturing methods. The synthesized Bi2Te3nanocrystals have a thickness of 35 ± 15 nm and a lateral dimension of 692 ± 186 nm. Thin films fabricated from these nanocrystals exhibit a peak power factor of 0.35 mW m−1·K−2at 433 K, which is among the highest reported values for flexible thermoelectric films. In order to evaluate the flexibility of the thin films, static and dynamic bending tests are performed while monitoring the change in electrical resistivity. After 1000 bending cycles over a 50 mm radius of curvature, the change in electrical resistance of the film is 23%. Using Bi2Te3solutions, the ability to print thermoelectric thin films with an aerosol jet printer is demonstrated, highlighting the potential of additive manufacturing techniques for fabricating flexible thermoelectric generators.
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Abstract Printing is a versatile method to transform semiconducting nanoparticle inks into functional and flexible devices. In particular, thermoelectric nanoparticles are attractive building blocks to fabricate flexible devices for energy harvesting and cooling applications. However, the performance of printed devices are plagued by poor interfacial connections between nanoparticles and resulting low carrier mobility. While many rigid bulk materials have shown a thermoelectric figure of merit
ZT greater than unity, it is an exacting challenge to develop flexible materials withZT near unity. Here, a scalable screen‐printing method to fabricate high‐performance and flexible thermoelectric devices is reported. A tellurium‐based nanosolder approach is employed to bridge the interfaces between the BiSbTe particles during the postprinting sintering process. The printed BiSbTe flexible films demonstrate an ultrahigh room‐temperature power factor of 3 mW m−1K−2andZT about 1, significantly higher than the best reported values for flexible films. A fully printed thermoelectric generator produces a high power density of 18.8 mW cm−2achievable with a small temperature gradient of 80 °C. This screen‐printing method, which directly transforms thermoelectric nanoparticles into high‐performance and flexible devices, presents a significant leap to make thermoelectrics a commercially viable technology for a broad range of energy harvesting and cooling applications. -
A solid‐state thermoelectric device is attractive for diverse technological areas such as cooling, power generation and waste heat recovery with unique advantages of quiet operation, zero hazardous emissions, and long lifetime. With the rapid growth of flexible electronics and miniature sensors, the low‐cost flexible thermoelectric energy harvester is highly desired as a potential power supply. Herein, a flexible thermoelectric copper selenide (Cu2Se) thin film, consisting of earth‐abundant elements, is reported. The thin film is fabricated by a low‐cost and scalable spin coating process using ink solution with a truly soluble precursor. The Cu2Se thin film exhibits a power factor of 0.62 mW/(m K2) at 684 K on rigid Al2O3substrate and 0.46 mW/(m K2) at 664 K on flexible polyimide substrate, which is much higher than the values obtained from other solution processed Cu2Se thin films (<0.1 mW/(m K2)) and among the highest values reported in all flexible thermoelectric films to date (≈0.5 mW/(m K2)). Additionally, the fabricated thin film shows great promise to be integrated with the flexible electronic devices, with negligible performance change after 1000 bending cycles. Together, the study demonstrates a low‐cost and scalable pathway to high‐performance flexible thin film thermoelectric devices from relatively earth‐abundant elements.
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