Materials, fabrication equipment, and methods for stable, sensitive photodetectors and image sensors made therefrom
Optically sensitive devices include a device comprising a first contact and a second contact, each having a work function, and an optically sensitive material between the first contact and the second contact. The optically sensitive material comprises a p-type semiconductor, and the optically sensitive material has a work function. Circuitry applies a bias voltage between the first contact and the second contact. The optically sensitive material has an electron lifetime that is greater than the electron transit time from the first contact to the second contact when the bias is applied between the first contact and the second contact. The first contact provides injection of electrons and blocking the extraction of holes. The interface between the first contact and the optically sensitive material provides a surface recombination velocity less than 1 cm/s.
1. An optically sensitive device comprising:
a first contact;
a second contact; and
an optically sensitive material comprising a cross-linking agent, at least one functional group of the cross-linking agent binding the first contact, the combination of the first contact, the cross-linking agent binding the first contact, and the optically sensitive layer comprise a Schottky contact, wherein electrons are withdrawn with high efficiency, and holes are injected with low efficiency.
2. The device of claim 1 , wherein the cross-linking agent comprises at least one thiol-terminated ligand from a group comprising benzenedithiol, ethanedithiol, and butanedithiol, or a multidentate molecule that includes a backbone, sidegroups or endgroups including thiols, amines, or carboxylates, and functional groups to confer solubility in polar, nonpolar, and partially polar solvents.
3. The device of claim 1 , wherein the optically sensitive material comprises a plurality of nanoparticles.
4. The device of claim 1 , wherein the optically sensitive material comprises nanoparticles selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, CdTe, Si, Ge, and C.
5. The device of claim 1 , wherein the optically sensitive material comprises a plurality of interconnected nanoparticles.
6. The device of claim 1 , wherein the first contact and the second contact are separated by a distance in the range of about 200 nm to about 2 μm.
7. The device of claim 1 , wherein the first contact comprises a material selected from the group consisting of Al, Ag, In, Mg, Ca, Li, Cu, Ni, NiS, TiN, TaN, TiO2, TixNy, ITO, Ru, TiSi, WSi2, TiOx doped with B, TiOx doped with C, TiOx doped with Co, TiOx doped with Fe, TiOx doped with Nd, and TiOx doped with N.
8. An optically sensitive device, comprising:
a first contact;
a second contact;
an interface layer; and
an optically sensitive material comprising a cross-linking agent, at least one functional group of the cross-linking agent binding the interface layer, the combination of the first contact, the cross-linking agent binding the interface layer, and the optically sensitive layer comprise a junction wherein electrons are withdrawn with high efficiency, and holes are injected with low efficiency.
9. The optically sensitive device of claim 8 , where the cross-linking agent comprises at least one thiol-terminated ligand from a group comprising benzenedithiol, ethanedithiol, and butanedithiol, or a multidentate molecule that includes a backbone, sidegroups or endgroups including thiols, amines, or carboxylates, and functional groups to confer solubility in polar, nonpolar, and partially polar solvents.
10. The optically sensitive device of claim 8 , wherein the first contact comprises a material selected from the group consisting of Al, Ag, In, Mg, Ca, Li, Cu, Ni, NiS, TiN, TaN, TiO2, TixNy, ITO, Ru, TiSi, WSi2, TiOx doped with B, TiOx doped with C, TiOx doped with Co, TiOx doped with Fe, TiOx doped with Nd, and TiOx doped with N.
11. The optically sensitive device of claim 8 , where the interface layer comprises a pure, clean surface of the metal of the first contact.
12. The optically sensitive device of claim 8 , where the interface layer includes an oxide.
13. The optically sensitive device of claim 12 , where the oxide is formed through exposure of the metal of the first contact to water, oxygen, or an oxidizing species.
14. The optically sensitive device of claim 8 , where the interface layer comprises TiO2, TiOxNy, Al2O3, Au2O3, PtO, PtO2, Ni2O3, WO3, PdO, ITO, or oxygen-rich ITO.
15. The optically sensitive device of claim 8 , where the thickness of the interface layer is in the range of about 2 nm to about 20 nm.
16. The optically sensitive device of claim 8 , where a portion of the interface layer has a bandgap that is larger than about 2 eV.