In non-limiting example embodiments, an electroluminescent device may include a lower structure including an emission area, and an encapsulation structure located on the lower structure. The lower structure may include a window. The window may be a light transmitting region or a notch. The light transmitting region may be spaced apart from the emission area and completely or partially surrounded by the emission area in a plan view. The notch may be formed at one side of the lower structure and recessed inward in a plan view such that one side of the emission area substantially conforms to the notch.