Compliant thermoelectric generators (TEGs) hold great promise in the field of self‐powered wearable electronics. Yet, the low heat transfer efficiency arising from large thermal resistance between elastic encapsulating materials and the contacted objects severely lowers the thermopower. This issue is much more challenging for organic TEG (oTEG) due to the high parasitic heat loss in the whole polymer system. Herein, guided by finite element analyses, a polydimethylsiloxane based composite coated with Cu is developed as a thermal interface without compromising the compliance of the oTEG, which possesses the merits of high thermal conductivity and significantly reduced thermal resistance, thus maximizing the temperature difference utilization ratio to 86%, which is 75.5% higher than for a routine oTEG. As a proof‐of‐concept, 50 pairs of p/n porous polyurethane/single‐wall carbon nanotube TE legs are integrated onto the designed substrate without further encapsulation. Both simulations and experiments on output performance under various thermal conditions are carried out, and show excellent agreement. The in situ output performance tests under various deformation conditions reveal the mechanical robustness of the oTEG. Finally, an oTEG functioning as a body heat harvester and an environment temperature sensor are demonstrated. The outstanding performances unambiguously demonstrate the success of the thermal interface design strategy for promoting oTEGs applied as wearable electronics.

Electromagnetic protection materials are widely used in both military and civilian fields. However, the limited wave-absorbing band and low transparency of conventional electromagnetic protection materials are the impediment for extensive applications. Here, a transparent and electrically tunable wave-absorbing metamaterial for stealth technology and electromagnetic protection has been theoretically and experimentally realized. The trend of the absorption feature change in simulation is consistent with that of the experiment results. The main part of this material adopts a sandwich structure consisting of two layers of indium tin oxide (ITO) and one layer of glass in between. The upper ITO layer is periodically patterned and combined with varactor diodes, which function as a frequency-selective surface. The effective operating frequency range is in the S-band, which covers the common frequency band of WiFi and many other electronic devices. The wave absorbing performance of this material can be electronically tunable by changing the applied voltage. The main absorption peak can be up to 90% with a tunable amplitude range of 30% and a tunable frequency band range of 1 GHz, and the transmittance of the sample in the visible is 80.23%. The metamaterial has high performance on electromagnetic shielding, whose effectiveness is larger than 30 dB in the range of 2.6–3.95 GHz. This transparent and tunable metamaterial has great potential for the applications in electromagnetic protection and stealth.

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