Vanadium, cobalt and strontium additives for use in aluminum back solar cell contacts

A method of at least one (I) reducing bow and (II) improving the electrical performance of an aluminum back contacted silicon solar cell, comprising:

• a. providing a silicon wafer substrate,
• b. applying to the substrate a paste comprising:
• i. about 60-95 wt % of aluminum,
• ii. an organometallic compound, and
• iii. a glass frit, to form a coated substrate, wherein the organometallic compound is a C1 to C30 organometallic compound of a metal selected from the group consisting of Co, Sr, V, and combinations thereof, such that the paste has an exothermic reaction peak at a temperature of at least 300° C. to less than 660° C. with a sample size of 5 to 200 mg when measured with differential scanning calorimetry at a heating rate of 20° C. per minute in air,
• c. firing the coated substrate,
• d. applying the paste to the silicon wafer substrate to form a coated substrate, and
• e. firing the coated substrate for a time and at a temperature sufficient to sinter the aluminum and fuse the glass fit and organometallic compound.

A method of improving the electrical performance of an aluminum back contacted silicon solar cell, comprising:

• a. providing a silicon wafer substrate
• b. providing a paste comprising:
• i. about 60-95 wt % of aluminum,
• ii. glass frit, and
• iii. a separate and distinct amount of a compound that supplies at least one of Co, Sr, and V, wherein the compound is not in the form of a phosphate,
• c. selecting a sufficient amount of such compound such that the paste provides an exothermic reaction peak, when measured with differential thermal analysis at a heating rate of 20 C per minute in air, at a temperature of at least 660 C to less than 900 C, with a sample size of 5 to 200 mg,
• d. applying the paste to the silicon wafer substrate to form a coated substrate, and
• e. firing the coated surface for a time and at a temperature sufficient to sinter the aluminum and fuse the glass fit and the compound.

A method of improving the electrical performance of an aluminum back contacted silicon solar cell, comprising:

• a. providing a silicon wafer substrate;
• b. providing a paste comprising:
• i. about 60-95 wt % of aluminum;
• ii. glass frit, and
• iii. a separate and distinct amount of at least one metal provided in the form of an organic compound or an inorganic compound, selected from the group consisting of Co, Sr, V, and combinations thereof, wherein a sufficient amount of the organic compound or inorganic compound is present in order to provide 100 ppmw to 10 wt % of the metal,
• c. applying the paste to the silicon wafer substrate to form a coated substrate, and
• d. firing the coated substrate for a time and at a temperature sufficient to sinter the aluminum and fuse the glass frit and at least one metal.