Brian M. Fish

Microstructural comparison of silicon solar cells' front-side Ag contact and the evolution of current conduction mechanisms

Microstructures of front-side Ag contact of crystalline Si solar cells fired at temperatures from below to above optimal were systematically investigated using advanced electron microscopy. Ag pastes studied included commercial pastes and an experimental paste containing nano-sized metallic Zn additive. Microstructures of optimally fired cells determined from cross-sectional and top-view images were found to be consistent with a primary tunneling mechanism for current flow (a “nano-Ag colloids assisted tunneling” model) due to the lack of Ag crystallites connecting the silver conductor line to the silicon emitter. We mapped the evolution of the interfacial microstructures across the firing temperature window and correlated it with cell performance. Our result sheds light on the relative importance of the two current transport models as the peak firing temperature was swept from below to above optimal.

Highly Sterically Hindered Olefins: A Case of E - and Z -Di- tert -butyl α,β-Unsaturated Acids

Use of a superbase in the Favorskii rearrangement of 12 resulted in the synthesis of highly sterically hindered olefins, (E)-2- tert-butyl-4,4-dimethyl-pent-2-enoic acid (4) and (Z)-2- tert-butyl-4,4-dimethyl-pent-2-enoic acid (3).

Contacts to silicon using a silver paste containing a phosphorus source

Performance enhancing phosphorus additives were found to be beneficial in front side conductive silver pastes. The phosphorus source at low levels increased the cell efficiencies from 0.1% to 0.3% on poly-crystalline and mono-crystalline Si cells. Better particle dispersion is seen when the phosphorus source is present. Additionally, specific contact resistivity measurements were made to quantify the contact resistivity.