A display substrate includes a first display substrate comprising a display area having an array of switching elements and a peripheral area surrounding the display area, a second display substrate facing the first display substrate, a color filter disposed on the display area of the first display substrate, a first backflow-blocking pattern including a material substantially the same as the color filter and disposed on the peripheral area and an insulation layer covering the color filter and the first backflow-blocking pattern, the insulation layer having a hole exposing, for outgas testing purposes, a corresponding portion of the first backflow-blocking pattern.