In one aspect, the present invention relates to a display. In one embodiment, the display has a substrate, and a plurality of pixels formed on the substrate and arranged in an array. Each pixel includes a driving transistor and a read-out transistor spatially formed on the substrate, where each transistor has a gate electrode, a drain electrode and a source electrode, an organic light emitting diode (OLED) having a cathode layer, a anode layer and an emissive layer formed between the cathode layer and the anode layer, and formed over the driving transistor and the read-out transistor such that the anode layer of the OLED is electrically connected to the source electrode of the driving transistor, and a photo sensor having a photosensitive layer formed between the anode layer of the OLED and the source electrode of the read-out transistor.