Disordered configuration leads to decoupled conductivity and thermopower

Advancements in thermoelectric performance are confronting challenges because of the coupling of thermoelectric properties. Therefore, it is crucial to design feasible strategies to disrupt this intrinsic coupling while concurrently optimizing the transport of both charge carriers and phonons. This study illustrates the potential of morphological disorder for thermoelectric decoupling by a graphene film (GF) with controllable morphology. A successful decoupling triggered by rising temperature leading to an increase in both the Seebeck coefficient (S) and the electrical conductivity (σ) has been achieved in crystalline GF by creating a disordered micromorphology (a-GF). Fundamentally, morphological disorder supports a temperature-controllable density of states (DOS) at the Fermi level (Ef) by adjusting the weak localization (WL) and the electron-electron interaction (EEI). Simultaneously, a temperature-independent thermal conductivity (k) was obtained in a-GF, attributed to defect phonon scattering rather than electron-phonon interaction. This research provides evidence for the beneficial impact of disordered morphology on thermoelectric decoupling and proposes a promising direction for the optimization of polycrystalline thermoelectric materials.