Light-induced aluminum plating on silicon for solar cell metallization
AssigneeArizona Board of Regents on behalf of Arizona State University
InventorsMeng Tao, Laidong Wang
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Abstract
Methods for light-induced electroplating of aluminum are disclosed herein. Exemplary methods may comprise preparing an ionic liquid comprising aluminum chloride (AlCl3) and an organic halide, placing the silicon substrate into the ionic liquid, illuminating the silicon substrate, the illumination passing through the ionic liquid, and depositing aluminum onto the silicon substrate via a light-induced electroplating process, wherein the light-induced electroplating process utilizes an applied current that does not exceed a photo-generated current generated by the illumination.
Claims21
A method for light-induced electroplating of aluminum directly onto a silicon substrate, the method comprising:
- preparing an ionic liquid comprising aluminum chloride (AlCl3) and an organic halide;
- placing the silicon substrate into the ionic liquid, wherein the surface of the silicon substrate is n-type and does not comprise a seed layer;
- illuminating the silicon substrate with a light source comprising at least one light-emitting diode with a wavelength of about 620 nanometers, the illumination passing through the ionic liquid, and a photo-generated current is generated by the illumination;
- while illuminating the silicon substrate with the light source, applying a current between an anode and a cathode to generate an applied current, wherein the applied current generates a current density of between 30 mA/cm2 and 50 mA/cm2;
- and
- depositing aluminum onto the surface of the silicon substrate via a light-induced electroplating process, wherein the light-induced electroplating process utilizes the applied current that does not exceed the photo-generated current generated by the illumination.
A method for processing a silicon solar cell, the method comprising:
- preparing an ionic liquid comprising aluminum chloride (AlCl3) and 1-ethyl-3-methylimidazolium tetrachloraluminate (EMIm-AlCl4);
- patterning a partially-processed silicon solar cell to expose an n-type surface of a silicon substrate;
- cleaning the n-type surface with at least one of hydrogen fluoride, hydrogen chloride, hydrogen peroxide, sodium hydroxide, potassium hydroxide, or ammonium hydroxide;
- bringing the n-type surface into contact with the ionic liquid, wherein the n-type surface does not comprise a seed layer;
- illuminating the n-type surface, wherein the illumination passes through the ionic liquid and wherein the illumination is generated at least partially by a light source comprising at least one light-emitting diode with a wavelength of about 620 nanometers, and a photo-generated current is generated by the illumination;
- while illuminating the silicon substrate with the light source, applying a current between an anode and a cathode to generate an applied current, wherein the applied current generates a current density of between 30 mA/cm2 and 50 mA/cm2;
- depositing aluminum onto the silicon substrate via a light-induced electroplating process, wherein the light-induced electroplating process comprises applying a current between an aluminum back electrode of the partially-processed silicon solar cell and an aluminum mesh disposed in the ionic liquid, and wherein the light-induced electroplating process utilizes the applied current that does not exceed the photo-generated current generated by the illumination;
- cleaning the deposited aluminum with deionized water;
- and
- annealing the deposited aluminum on the silicon substrate to reduce the resistivity of the electroplated aluminum.
Dependencies are inferred from the claim text.