Optical and electrochromic properties of annealed lithium-molybdenum-bronze thin films

Optical band gaps, Urbach inverse slopes, and coloration bands of various samples of annealed, microcrystalline Li_xMoO₃-bronze thin films in the concentration range 03. Using this model, it becomes more certain that the contributions to the Urbach absorption edge for the annealed-molybdenum bronzes are coming from the structural and compositional disorder. In another finding, it was found that the absorption-peak energy for the annealed data was about 1.5–1.6 eV, which is still broad and asymmetrical, and therefore, it is almost of the Mo⁶⁺ (or Mo⁴⁺)-Mo⁵⁺ intervalence or polaronic type. Using the polaron model, the half-bandwidth of the coloration bands of investigated, annealed Li_xMoO₃-thin films was found to be almost constant, which is consistent with the nonrigid band behavior.