Example embodiments disclose transistors, methods of manufacturing the same, and electronic devices including transistors. An active layer of a transistor may include a plurality of material layers (oxide layers) with different energy band gaps. The active layer may include a channel layer and a photo sensing layer. The photo sensing layer may have a single-layered or multi-layered structure. When the photo sensing layer has a multi-layered structure, the photo sensing layer may include a first material layer and a second material layer that are sequentially stacked on a surface of the channel layer. The first layer and the second layer may be alternately stacked one or more times.