Portable electronic device and operating method thereof

An operating method of a portable electronic device comprising:

• providing a first display which is transparent;
• arranging an optical module positioned below the first display, electrically connecting the optical module to a circuit board of the portable electronic device;
• controlling the portable electronic device to a first mode by switching off the optical module, and switching on the first display to display a first image;
• detecting whether a trigger event is received;
• and
• when the trigger event is detected, switching the portable electronic device from the first mode to a second mode by switching off the first display and switching on the optical module to receive external light passing through the first display.