We propose an inexpensive, scalable approach for achieving extremely high values of the Seebeck coefficient (α) by exploiting natural superlattice structure in Aurivillius phase oxides. In particular, we report α ≈ 319 mV/K at 300 K a composite compound SrBi4Ti4O15 (as matrix) and perovskite material (e.g., La0.7Sr0.3MnO3 or, La0.7Sr0.3CoO3 as filler). Such colossal value may be attributed to c...