Thick film pastes for fire through applications in solar cells
AssigneeHeraeus Precious Metals North America Conshohocken LLC
InventorsNazarali Merchant, Aziz S. Shaikh, Srinivasan Sridharan
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Abstract
Formulations and methods of making solar cell contacts and cells therewith are disclosed. The invention provides a photovoltaic cell comprising a front contact, a back contact, and a rear contact. The back contact comprises, prior to firing, a passivating layer onto which is applied a paste, comprising aluminum, a glass component, wherein the aluminum paste comprises, aluminum, another optional metal, a glass component, and a vehicle. The back contact comprises, prior to firing, a passivating layer onto which is applied an aluminum paste, wherein the aluminum paste comprises aluminum, a glass component, and a vehicle.
Claims9
A method of making a photovoltaic cell comprising:
- a. providing a silicon wafer having a first side and a second side,
- b. applying a phosphorus source to the first side of the silicon wafer,
- c. firing the wafer to form a phosphorus glass layer on the first side of the silicon wafer,
- d. removing at least a portion of the phosphorus glass layer from the first side of the silicon wafer,
- e. polishing the second side of the silicon wafer,
- f. applying a passivating layer to the first and second sides of the wafer,
- g. applying to the first side a silver paste comprising, prior to firing,
- i. silver,
- ii. a glass component, and
- iii. a vehicle,
- h. applying to the second side an aluminum paste comprising, prior to firing,
- i. aluminum,
- ii. a glass component, and
- iii. a vehicle,
- wherein (g) and (h) can be performed in any order, and
- i. firing the wafer for a time and temperature sufficient to adhere the silver to the front side and the aluminum to the back side, thereby forming front and back contacts.
Dependencies are inferred from the claim text.