An organic light-emitting display device includes a substrate, a first buffer layer and a second buffer layer on the substrate, a thin film transistor on the second buffer layer, an organic light-emitting diode electrically connected with the thin film transistor, and a photo sensor with an intrinsic region on the second buffer layer, wherein the photo sensor is capable of absorbing red light from the organic light-emitting diode and of exhibiting quantum efficiency of from about 50% to about 90%.