Photodetectors integrated into thin-film transistor backplanes

1 . An electronic device, comprising:

a stack, including,

a substrate; and

a multi-layer structure deposited on the substrate and including a set of thin-film transistors (TFTs); and

a photodetector attached to the multi-layer structure and defined by an organic photosensitive material that is electrically connected to a transistor in the set of TFTs, wherein the multi-layer structure comprises a Low-Temperature Polycrystalline Oxide (LTPO) organic light-emitting diode (OLED) display backplane.

2 . The electronic device of claim 1 , further comprising:

a housing defining at least part of an interior volume and an opening into the interior volume;

a cover mounted to the housing to cover the opening and further define the interior volume; and

a display mounted within the interior volume and viewable through the cover;

wherein:

the stack is attached to a side of the display opposite the cover; and

the photodetector is positioned to receive light through the display.

3 . The electronic device of claim 2 , further comprising at least one of a lens, an optical waveguide, an optical polarizer, or an optical film, positioned between the display and the stack.

4 . The electronic device of claim 2 , wherein:

the multi-layer structure including the set of TFTs is a first multi-layer structure including a first set of TFTs; and

the display includes:

a second substrate;

a second multi-layer structure deposited on the second substrate and including a second set of TFTs; and

an organic light-emitting material deposited on the second multi-layer structure and electrically connected to a set of drive transistors in the second set of TFTs.

5 . The electronic device of claim 2 , wherein the display comprises a bottom-emission liquid crystal display (LCD).

6 . The electronic device of claim 1 , wherein the organic photosensitive material forms a planarization layer of the multi-layer structure.

7 . The electronic device of claim 6 , wherein the planarization layer is a first planarization layer, the electronic device further comprising:

a second planarization layer between the first planarization layer and the set of TFTs.

8 . The electronic device of claim 6 , wherein:

the organic photosensitive material forms at least a first planarization layer and a second planarization layer of the multi-layer structure; and

the electronic device further comprises an electrode positioned between the first planarization layer and the second planarization layer and electrically connected to the transistor.

9 . The electronic device of claim 1 , wherein the photodetector comprises an organic avalanche photodiode (O-APD).

10 . An electronic device, comprising:

a stack, including,

a substrate; and

a multi-layer structure deposited on the substrate and including:

a first set of layers including a set of thin-film transistors (TFTs) and a TFT oxide layer; and

a second set of layers including a PIN diode, the second set of layers distinct from the first set of layers; wherein:

the PIN diode is configured to operate as a photodetector and receive at least one wavelength of electromagnetic radiation;

the PIN diode is electrically connected to at least one TFT in the set of TFTs,

the at least one TFT has a gate formed in the TFT oxide layer;

the PIN diode is electrically connected to an electrode comprising titanium; and

the titanium operates as a hydrogen getter.

11 . The electronic device of claim 10 , wherein:

the first set of layers and the second set of layers share an electrical contact layer; and

each of the PIN diode and the at least one TFT is connected to a respective electrical contact in the electrical contact layer.

12 . The electronic device of claim 10 , wherein the first set of layers further includes a silicon-based TFT.

13 . The electronic device of claim 10 , wherein the PIN diode is silicon-based.

14 . The electronic device of claim 10 , wherein the PIN diode is electrically connected to an electrode that extends over the at least one TFT.