Display panels and display devices

A display panel, comprising a substrate, the substrate comprising:

• a display area comprising pixel units arranged in an array and a signal line connecting the pixel units;
• a front surface of the substrate comprising the display area;
• a back surface of the substrate facing away from the display area;
• a side surface of the substrate connecting the front surface of the substrate with the back surface of the substrate;
• and
• a mounting groove recessed into the substrate from the side surface of the substrate;
• the display panel further comprising a fan-out line disposed in the mounting groove, one end of the fan-out line being connected to the signal line, and the other end meandering from the mounting groove to the back surface of the substrate,
• wherein the display area of the display panel comprises a first sub-display area, a second sub-display area, and a third sub-display area arranged between the first sub-display area and the second sub-display area, the mounting groove is located between the first sub-display area and the second sub-display area, the third sub-display area is located below the mounting groove and adjacent to a bottom edge of the mounting groove,
• wherein the mounting groove comprises a sensor disposing area,
• wherein the mounting groove comprises an inner wall located within the substrate, and a thickness of the inner wall of the mounting groove is the same as a thickness of the substrate.