Stacked body having a light emitting element and a light detecting element for measuring an amount of light, a light emitting device, and an image formation device

A stacked body for measuring an amount of light, said stacked body comprising:

• a light emitting element including a light emitting layer which emits light;
• and
• a light detecting element including:
• (i) a gate electrode which comprises a transmissive part and a light blocking part, and (ii) a light detecting region which is provided between the light emitting layer and the light blocking part of the gate electrode, wherein the light detecting element detects incident light emitted by the light emitting layer,
• wherein the transmissive part of the gate electrode is an opening,
• wherein the light blocking part of the gate electrode includes a material which blocks incident light emitted by the light emitting layer, and
• wherein the light emitting layer overlaps with the light detecting region and with the transmissive part of the gate electrode as viewed in a thickness direction of the light emitting layer such that some of the light emitted from the light emitting layer radiates onto the light detecting region and some other of the light emitted from the light emitting layer passes through the transmissive part of the gate electrode.