High Figure‐of‐Merit Telluride‐Based Flexible Thermoelectric Films through Interfacial Modification via Millisecond Photonic‐Curing for Fully Printed Thermoelectric Generators

Abstract The thermoelectric generator (TEG) shows great promise for energy harvesting and waste heat recovery applications. Cost barriers for this technology could be overcome by using printing technologies. However, the development of thermoelectric (TE) materials that combine printability, high‐efficiency, and mechanical flexibility is a serious challenge. Here, flexible (SbBi)2(TeSe)3‐based screen‐printed TE films exhibiting record‐high figure of merits (ZT) and power factors are reported. A high power factor of 24 µW cm−1 K−2 (ZTmax ≈ 1.45) for a p‐type film and a power factor of 10.5 µW cm−1 K−2 (ZTmax ≈ 0.75) for an n‐type film are achieved. The TE inks, comprised of p‐Bi0.5Sb1.5Te3 (BST)/n‐Bi2Te2.7Se0.3 (BT) and a Cu‐Se‐based inorganic binder (IB), are prepared by a one‐pot synthesis process. The TE inks are printed on different substrates and sintered using photonic‐curing leading to the formation of a highly conducting β‐Cu2−δSe phase that connects “microsolders,” the grains resulting in high‐performance. Folded TEGs (f‐TEGs) are fabricated using the materials. A half‐millimeter thick f‐TEG exhibits an open‐circuit voltage (VOC) of 203 mV with a maximum power density (pmax) of 5.1 W m−2 at ∆T = 68 K. This result signifies that a few millimeters thick f‐TEG could power Internet‐of‐Things (IoTs) devices converting low‐grade heat to electricity.