Photonic feedback organic photodiodes and upconverters

The optical upconverter comprising a substrate with a photodiode layer coupled to a stacked organic light emitting diode (OLED), the stacked OLED comprising at least two OLED light-emitting units separated by a charge-generation layer (CGL);

• wherein photocurrent generated by the photodiode layer causes light emission from the stacked OLEDs;
• and
• the photodiode layer is configured to generate the photocurrent from light that falls within at least a first frequency band;
• the stacked OLED is configured to generate light that falls within a second frequency band;
• wherein the photodiode layer is configured to receive light of the second frequency band from the stacked OLED and generate additional photocurrent from the second frequency band as well as the first frequency band;
• wherein the stacked OLED additionally comprises bottom and top electrodes electrically connected to a power source wherein the top electrode is transparent or semitransparent to the light of the second frequency band;
• which additionally comprises:
• a substrate that is transparent to light of the first frequency band wherein:
• the bottom electrode is at least partially transparent to light of the first frequency band, and the photodiode layer is located between the bottom and top electrodes of the stacked OLED;
• and
• wherein the power source provides a voltage bias that prevents the photodiode layer from generating a photocurrent from light that falls within at least a first frequency band for at least some period of time during operation.

A device wherein two optical upconverters are vertically stacked, each optical upconverter comprising a substrate with a photodiode layer coupled to a stacked organic light emitting diode (OLED), the stacked OLED comprising at least two OLED light-emitting units separated by a charge-generation layer (CGL);

• wherein photocurrent generated by the photodiode layer causes light emission from the stacked OLEDs;
• and
• the photodiode layer is configured to generate the photocurrent from light that falls within at least a first frequency band;
• the stacked OLED is configured to generate light that falls within a second frequency band;
• wherein the photodiode layer is configured to receive light of the second frequency band from the stacked OLED and generate additional photocurrent from the second frequency band as well as the first frequency band;
• wherein the stacked OLED additionally comprises bottom and top electrodes electrically connected to a power source wherein the top electrode is transparent or semitransparent to the light of the second frequency band, and
• wherein the top electrode of the bottom upconverter is common with the bottom electrode of the top upconverter and the photodiode layer in each upconverter responds to a different first frequency from the other and the stacked OLED in each upconverter generates light of a different second frequency from the other.