Ultra-thin doped noble metal films for optoelectronics and photonics applications
Electrically conductive, thin, smooth films are provided that comprise silver (Ag) and a conductive metal, such as aluminum (Al), titanium (Ti), nickel (Ni), chromium (Cr), gold (Au), magnesium (Mg), tantalum (Ta), germanium (Ge) or combinations thereof. In other alternative variations, electrically conductive, thin, smooth films are provided that comprise gold (Au) or copper (Cu) and a conductive metal, such as aluminum (Al), titanium (Ti), nickel (Ni), chromium (Cr), gold (Au), magnesium (Mg), tantalum (Ta), germanium (Ge) or combinations thereof. Such materials have excellent electrical conductivity, may be ultra-thin, flexible, transparent, and have low optical loss. Assemblies incorporating such films and methods of making the films are also provided. The assemblies may be used in photovoltaic and light emitting devices with high power conversion efficiencies or optical meta-materials that exhibit high transmittance and homogeneous response, among others.
1. A device comprising an assembly that comprises:
a substrate; and
an electrically conductive transparent thin film comprising silver (Ag) at greater than or equal to about 90 atomic % of the total composition of the thin film and a conductive metal comprising aluminum (Al) present at greater than 2 atomic % to less than or equal to about 10 atomic % of the total composition of the thin film disposed directly on the substrate, the electrically conductive transparent thin film having a thickness of greater than or equal to about 6 nm to less than or equal to about 11 nm with a smooth surface having a root mean squared (RMS) surface roughness that is less than or equal to about 1 nm, so that the electrically conductive thin film is above a percolation threshold, has a sheet resistance of greater than or equal to about 10 Ohm/square to less than or equal to about 75 Ohm/square, and is transparent to electromagnetic light in a visible spectral range and an ultraviolet spectral range.
2. The device of claim 1 , wherein the electrically conductive thin film has a sheet resistance of greater than or equal to about 10 Ohm/square to less than or equal to about 20 Ohm/square.
3. The device of claim 1 , wherein the electrically conductive transparent thin film defines a first side and a second opposite side, wherein the substrate is adjacent to the first side and a second material is disposed on the second opposite side, and the second material comprises an electronic charge or ion transporting or blocking layer, a dielectric layer, or a two-dimensional (2-D) semiconductor.
4. The device of claim 3 , wherein the second material comprises an electronic charge or ion transporting or blocking layer and the assembly further comprises a photovoltaic active material disposed adjacent to the electronic charge or ion transporting or blocking layer.
5. The device of claim 1 , wherein the device is a photovoltaic cell or a light emitting diode and the assembly comprising the electrically conductive transparent thin film is a transparent conductive electrode (TCE) incorporated within the device.
6. The device of claim 1 , wherein the electrically conductive transparent thin film defines a first side and a second opposite side, wherein the substrate is adjacent to the first side and a dielectric material is disposed on the second opposite side so that the assembly forms a metamaterial with predetermined optical and electrical properties.
7. The device of claim 1 , wherein the electrically conductive transparent thin film defines an electrode.
8. The device of claim 7 , wherein the electrically conductive thin film is reflective to electromagnetic light having a wavelength in an infrared spectral range.
9. The device of claim 7 , wherein the device is a light emitting diode, a transparent or see-through display, a window that reflects infrared light, or a smart switchable window that incorporates the electrode.
10. The device of claim 1 , wherein the electrically conductive transparent thin film reflects infrared light.
11. The device of claim 1 , wherein the electrically conductive transparent thin film defines a first side and a second opposite side, wherein the substrate is adjacent to the first side of the electrically conductive thin film and a second material is adjacent to the second opposite side of the electrically conductive thin film.
12. The device of claim 11 , wherein the second material comprises a dielectric material.
13. The device of claim 1 , wherein the electrically conductive transparent thin film is annealed.
14. A method of making an assembly comprising an electrically conductive thin film for a device, the method comprising:
co-depositing silver (Ag) and a conductive metal comprising aluminum (Al) directly onto a substrate to form a continuous thin film comprising silver (Ag) at greater than or equal to about 90 atomic % of the total composition of the thin film and the conductive metal at greater than 2 atomic % to less than or equal to about 10 atomic % of the total composition of the thin film, wherein the thin film has a thickness of greater than or equal to about 6 nm to less than or equal to about 11, is electrically conductive having a sheet resistance of greater than or equal to about 10 Ohm/square to less than or equal to about 75 Ohm/square, has a smooth surface with a root mean squared (RMS) surface roughness that is less than or equal to about 1 nm so that the thin film is above a percolation threshold and is transparent to electromagnetic light in a visible spectral range and an ultraviolet spectral range.
15. The method of claim 14 , wherein the co-depositing is via a physical vapor deposition (PVD) process or a sputtering process.
16. The method of claim 14 , further comprising applying an electron transporting and hole blocking layer or a hole-transporting and electron-blocking layer onto the continuous thin film or applying a dielectric metal oxide material or a two-dimensional semiconductor material onto the continuous thin film.
17. A device comprising an assembly that comprises:
a substrate; and
an electrically conductive transparent thin film consisting essentially of silver (Ag) at greater than or equal to about 90 atomic % of the total composition of the thin film and aluminum (Al) present at greater than 2 atomic % to less than or equal to about 10 atomic % of the total composition of the electrically conductive transparent thin film disposed directly on the substrate and having a thickness of greater than or equal to about 6 nm to less than or equal to about 11 nm and a smooth surface with a root mean squared (RMS) surface roughness that is less than or equal to about 1 nm, so that the electrically conductive thin film is above a percolation threshold, has a sheet resistance of greater than or equal to about 10 Ohm/square to less than or equal to about 75 Ohm/square, and is transparent to electromagnetic light in a visible spectral range and an ultraviolet spectral range.
18. The device of claim 17 , wherein the electrically conductive thin film has a sheet resistance of greater than or equal to about 10 Ohm/square to less than or equal to about 20 Ohm/square.
19. The device of claim 17 , wherein the electrically conductive transparent thin film is annealed.
20. A device comprising an assembly that comprises:
a substrate; and
an electrically conductive transparent thin film comprising silver (Ag) at greater than or equal to about 90 atomic % of the total composition of the thin film and a conductive metal comprising aluminum (Al) present at greater than 2 atomic % to less than or equal to about 10 atomic % of the total composition of the thin film disposed directly on the substrate, the electrically conductive transparent thin film having a thickness of greater than or equal to about 6 nm to less than or equal to about 11 nm with a smooth surface having a root mean squared (RMS) surface roughness that is less than or equal to about 1 nm, so that the electrically conductive thin film is above a percolation threshold, has a sheet resistance of greater than or equal to about 30 Ohm/square to less than or equal to about 75 Ohm/square, and is transparent to electromagnetic light in a visible spectral range and an ultraviolet spectral range.
21. The device of claim 20 , wherein the electrically conductive transparent thin film is annealed.