Flexible Porous Ag₂Se Films: From Freestanding Inorganic Films to Inorganic‐Network/Organic‐Skeleton Thermoelectric Generators

Abstract Silver selenide (Ag₂Se) flexible films are promising near‐room‐temperature thermoelectric candidates for low‐grade heat harvesting. However, existing Ag₂Se films are generally attached on substrates, which impedes further flexibility improvement of the films and constrains the scenarios of applications. Here a cost‐effective and scalable strategy is presented, which combines screen printing and annealing, for synthesizing freestanding Ag₂Se inorganic films with different densities of pores. High‐density pores and thin thickness endow the films with high flexibility, while films with low‐density pores obtain higher power factor. Furthermore, by utilizing the porous microstructure, a composite structure consisting of a Ag₂Se conductive network and an organic polydimethylsiloxane (PDMS) skeleton is fabricated, which further improves films’ stability under bending and torsion. Finally, a flexible thermoelectric generator comprising five Ag₂Se/PDMS legs and encapsulated PDMS outputs a voltage of 20.2 mV and a maximum power of 810 nW (the corresponding power density is 5.4 W m⁻²) at a temperature difference of 30 K, verifying potential application at near room temperature. This work offers a useful paradigm for fabricating substrate‐free Ag₂Se porous films with high flexibility for near‐room‐temperature thermoelectric applications.