In situ Synthesized Staggered‐Layer‐Boosted Flexible Ag ₂ Se and Cu ₂ Se Thin Films for Wearable Thermoelectric Power Generators

Abstract Flexible thermoelectric generators (TEGs) have been considered as a promising power source for rapidly developing wearable microelectronic devices, but how to integrate high‐performance materials and device design to prepare an available wearable TEGs is still challenging. In this study, n‐type silver selenide (Ag ₂ Se) and p‐type copper selenide (Cu ₂ Se) films are prepared by in situ full metal selenization strategy combined with screen‐printing technique, avoiding a high‐temperature process and expensive equipments. Further, a 3D structured thermoelectric module with 42 thermoelectric p‐n leg pairs is designed and configured by vertically embedding Ag₂Se and Cu₂Se thin films into a 4 mm‐thick silicone layer that provides insulation and structural support. The device consistently delivers power, achieving the maximum open‐circuit voltage of 113 mV at a temperature difference of 60 K, with a maximum power density of 234.3 µW cm ^{− 2} . Under bending stress, the flexible TEG still has 81% retention rate of initial power density after 1500 bending cycles, indicating the good bending property. It can also generate a voltage of 3.6 and 7 mV, respectively, when worn on an arm with or without a fan expanding temperature difference. The work highlights a simple method to obtain efficient selenide thermoelectric films for cost‐effective flexible 3D structured TE devices.