Nickel oxide sol-gel ink

1. A method for forming a nickel oxide layer on a substrate, comprising:

depositing a nickel oxide precursor ink on a substrate, wherein the nickel oxide precursor ink comprises:

a solvent comprising diols, alcohol amines, and water;

Ni(NO 3 ) 2 ·6H 2 O; and

at least one metal acetate selected from the group consisting of Ni(CH 3 CO 2 ) 2 ·4H 2 O and Cu(CH 3 CO 2 ) 2 ·1H 2 O;

annealing the nickel oxide precursor ink at a temperature between 250° to 400° Celsius for between 10 minutes and 6 hours to form a nickel oxide layer; and

cooling the nickel oxide layer.

2. The method of claim 1 , wherein: the solvent comprises ethylene glycol, ethanolamine and water.

3. The method of claim 1 , wherein the substrate is selected from the group consisting of glass, p-doped silicon, n-doped silicon, sapphire, magnesium oxide, mica, polymers, ceramics, fabrics, wood, drywall, metal, ITO-coated glass, FTO-coated glass, or combinations thereof.

4. The method of claim 1 , wherein the substrate is coated with a conductive material selected from the group consisting of group consisting of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), cadmium oxide (CdO), zinc indium tin oxide (ZITO), aluminum zinc oxide (AZO), aluminum (Al), gold (Au), calcium (Ca), magnesium (Mg), titanium (Ti), steel, chromium (Cr), copper (Cu), silver (Ag), nickel (Ni), tungsten (W), molybdenum (Mo), carbon, and combinations thereof.

5. The method of claim 1 , wherein the nickel oxide precursor ink is deposited on the substrate under an environment having a humidity between 10% and 50% and a temperature between 20° and 60° Celsius.

6. The method of claim 1 , wherein the annealing takes place at a temperature of 310° Celsius for a time period of two hours.