TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The aluminum paste composition comprising 15-68 wt.% of at least one siloxane, 25-84.9 wt.% of an aluminum powder, and 0.1-10 wt.% of an organic vehicle. The aluminum paste composition further comprises an optional indium-free additive, where the optional indium-free additive comprises lead-free glass frit, amorphous silicon dioxide, organometallic compounds, boron-containing compounds and/or metal salts. Preferred Process: The step of applying the aluminum paste on a back-side of a p-type silicon substrate comprises screen printing the aluminum paste on the back-side of the p-type silicon substrate, and drying the aluminum paste at 100-175 degrees C for 5-60 minutes or 175-350 degrees C for 15-300 second, or drying the aluminum paste by ramping the temperature from room temperature to a drying temperature of 100-200 degrees C at a ramp-rate in the range of 2-50 degrees C/minutes and holding the temperature constant at the drying temperature for 1-60 minutes.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The siloxane comprises: at least one of a mono functional "M" unit of formula (RR1aR1bMSiO1/2) (I); a difunctional "D" unit of formula (R1R2SiO2/2) (II); or a trifunctional "T" unit of formula (R3SiO3/2) (II). The siloxane is: at least one of a linear siloxane of formula (M-Dn-2-M) (IV); a cyclic siloxane of formula (Dn); or a branched siloxane of formula (TkDmM2+k) (V). The siloxane comprises at least one of poly(dimethylsiloxane), poly(methylhydrogensiloxane), poly(dimethylsiloxane-comethylphenylsiloxane) and/or poly(ethylmethylsiloxane-co-( alpha -methylphenylethyl)methylsiloxane). The lead-free glass frit comprises at least 10 wt.% of one of a bismuth oxide and/or an antimony oxide. The siloxane is present at 0.035-0.51 wt.%, 20-60 wt.% or 15-68 wt.%, such that the weight ratio of aluminum powder to siloxane is present at 152:1-2000:1.R, R1a, R1b, R2, and R3 = hydrocarbyl groups (optionally substituted);R1 = hydrocarbyl groups (optionally substituted) or H;k (k greater than or equal to 1) = number of branches;m (m greater than or equal to 0) = number of difunctional units, where the total number of silicon atoms (n) in the branched siloxane is n = 2+2k+m; andn = 2-300, preferably 2-80 or 15-140. EXAMPLE - Typical composition comprised (in wt.%): aluminum paste (sufficient amount); siloxane (0.3); calcium pyrophosphate (0.3); and frit (0.3).