An OLED device includes a low-temperature poly-silicon (LTPS) thin-film transistor having a first channel layer, a first gate electrode, a first source electrode and a first drain electrode; an oxide semiconductor thin-film transistor having a second channel layer, a second gate electrode, a second source electrode and a second drain electrode; and a functional layer between the first channel layer and the first gate electrode. The second channel layer is in contact with an upper surface of the functional layer.