A display panel for OLED device having a display mode and an input mode. The display panel comprises a driving unit, a capacitor, a light-emitting diode, a light-detecting unit, and a detecting unit. The driving unit has a control electrode coupled to a first node, a first electrode coupled to a first voltage source, and a second electrode. The capacitor and the light-detecting unit are coupled between the first node and the first voltage source. The light-emitting diode is coupled between the control electrode of the driving unit and a second voltage source. In the input mode, the detecting unit detects a voltage at the first node.