Thermoelectric (TE) technology provides a new way to directly harvest and convert the heat continuously released from the human body. The greatest challenge for TE materials applied in wearable TE generators is compatible with the constantly changing morphology of the human body while offering a continuous and stable power output. Here, a stretchable carboxylic single-walled carbon nanotube (SWNT)-based TE fiber is prepared by an improved wetspinning method. The stable Seebeck coefficient of the annealed carboxylic SWNT-based TE fiber is 44 μV/K even under the tensile strain of ∼30%. Experimental results show that the fiber can continue to generate constant TE potential when it is changed to various shapes. The new stretchable TE fiber has a larger Seebeck coefficient and more stretchability than existing TE fibers based on the Seebeck effect, opening a path to using the technology for a variety of practical applications.

Compact solid‐state refrigeration systems that offer a high specific cooling power and a high coefficient of performance (COP) are desirable in a wide range of applications where efficient and localized heat transfer is required. Here, a double‐unit electrocaloric (EC) polymer‐based refrigeration device with high intrinsic thermodynamic efficiency is demonstrated using a flexible EC polymer film with improved performance by doping plasticizer and an electrostatic actuation mechanism. The double‐unit refrigeration device achieves a large temperature span of 4.8 K, which is 71% higher than that of the single‐unit device. A specific cooling power of 3.6 W g−1 and a maximum COP of 8.3 for the cooling device are produced. The surface temperature of a central processing unit (CPU) cooled by an active EC device is 22.4 K lower than that of the CPU cooled in air. The highly efficient and compact EC cooling device demonstrated here not only leapfrogs the performance of existing solid‐state cooling technologies, but also brings solid state cooling closer to reality for a variety of practical applications that require compact or mechanically flexible refrigeration.

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CPU) moved into multi-core, coolers can deal with the chip as a single-site heat source for effective cooling. But the multi-core CPU is packaged as a whole, and the localized overheating site in one core can heat others up. The localized overheating site makes the thermal challenge much more difficult, and it caused more than 55% of all failures in current electronics. [5,6] As operating temperature approaches 70-80 °C, the performance of electronics will degrade by ≈10% for every 2 °C increase. [7] So, the precise cooling technology in integrated circuits has become increasingly a restrictive factor affecting the development of the electronics industry. [8][9][10] Vapor-compression refrigeration systems are bulky, complex, and difficult to scale down to meet the cooling demands of electronic chips. Existing refrigerants also have high global warming potentials, and present an environmental risk upon leakages or improper disposal. Therefore, it is urgent and vital to develop a highly efficient, environmentally friendly, compact, and portable refrigeration device to achieve precise cooling.Solid-state cooling systems, especially caloric-effect-based refrigeration such as the elasto/baro caloric effect, [11] magnetocaloric effect, [12] and electrocaloric (EC) effect, [8,9,[13][14][15] have the advantages of no compressors and conventional liquid or vapor refrigerants, environmental protection, and rapid cooling. The EC refrigeration has been praised for its high coefficient of performance (COP), simple setup, low cost, and feasibility for embedded application in compact integrated circuits. [13] Thus, they can solve the practical cooling requirements of integrated microelectronics that traditional compressor technology is difficult to address. The EC is a reversible adiabatic temperature change (ΔT) and/or isothermal entropy change (ΔS) in dielectric materials induced by an external electric field change (ΔE). [8] Although a large voltage is applied, the generated current and corresponding power consumption are still very small, because of the insulating properties of the EC materials. Therefore, EC refrigeration device exhibits a great application prospect in miniature electronics cooling.Compared to the inherent brittleness of EC multilayer ceramic capacitors, [16,17] the poly(vinylidene fluoride) (PVDF)based ferroelectric polymers have been praised for their light weight, large isothermal entropy change, flexibility, and More than 55% of electronic failures are caused by damage from localized overheating. Up to now, there is still no efficient method for targeted temperature control against localized overheating. Although some existing thermal management devices handle this issue by full coverage cooling, it generates a lot of useless energy consumption. Here, a highly efficient pixel-matrix electrocaloric (EC) cooling device is reported, which can realize a targeted and differential thermal management. The modified poly(vinylidene fluoride-tertrifluoroethylene-chlorofluoroethylene) reaches a large adiabatic te...

Highlights Shape memory self-soldering tape used as conductive interconnecting material. Perfect shape and conductivity memory performance and anti-fatigue performance. Reversible strong-to-weak adhesion switched by temperature. Abstract With practical interest in the future applications of next-generation electronic devices, it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace traditional rigid solder tin and silver paste of high melting temperature or corrosive solvent requirements. Herein, we design highly stretchable shape memory self-soldering conductive (SMSC) tape with reversible adhesion switched by temperature, which is composed of silver particles encapsulated by shape memory polymer. SMSC tape has perfect shape and conductivity memory property and anti-fatigue ability even under the strain of 90%. It also exhibits an initial conductivity of 2772 S cm−1 and a maximum tensile strain of ~ 100%. The maximum conductivity could be increased to 5446 S cm−1 by decreasing the strain to 17%. Meanwhile, SMSC tape can easily realize a heating induced reversible strong-to-weak adhesion transition for self-soldering circuit. The combination of stable conductivity, excellent shape memory performance, and temperature-switching reversible adhesion enables SMSC tape to serve two functions of electrode and solder simultaneously. This provides a new way for conductive interconnecting materials to meet requirements of modern electronic devices in the future.

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In article number 2003771, Rujun Ma and co‐workers report a highly efficient double‐unit solid‐state refrigeration device based on two‐layer modified electrocaloric polymer stacks actuated by electrostatic forces. The availability and the high‐efficiency of the device for cooling the central processing unit provides a unique option for thermal management of microcircuits in the future.