Patent ID: 8759668

Claim:
A solar cell comprising two separate layers, a silicon layer and a back contact layer deposited over a back surface of the silicon layer, wherein the back contact layer comprises a p + layer with an active peak doping concentration of (Al+B) of about 10 19 to about 10 20 atoms per cubic centimeter, the back contact layer made from a mixture, wherein, prior to firing, the mixture comprises: a. at least one aluminum source providing aluminum in an amount of about 50 wt % to about 85 wt % of the mixture, b. at least one boron source providing boron in an amount of about 0.25 wt % to about 20 wt % of the mixture, and c. about 0.1 to about 10 wt % of a glass component, including (i) a first glass composition, wherein the first glass composition comprises 1. about 15 to about 75 mole % PbO and 2. about 5 to about 50 mole % of (B 2 O 3 +SiO 2 ), and (ii) a second glass composition comprising 3. about 30 to about 40 mole % (Li 2 O+Na 2 O+K 2 O), 4. about 2 to about 26 mole % TiO 2 , and 5. about 5 to about 75 mole % (B 2 O 3 +SiO 2 ), wherein the first and second glass compositions are present in a weight ratio of about 5:1 to 1:5.