Multifold Electrical Conductance Enhancements at Metal-Bismuth Telluride Interfaces Modified Using an Organosilane...

Controlling electrical transport across metal-thermoelectric interfaces is key to realizing high efficiency devices for solid state refrigeration and waste-heat harvesting. We obtain up to 17-fold increases in electrical contact conductivity Σ_c by inserting a mercaptan-terminated organosilane monolayer at Cu-Bi₂Te₃ and Ni-Bi₂Te₃ interfaces, yielding similar Σ_c for both metals by offsetting an otherwise 7-fold difference. The Σ_c improvements are underpinned by silane-moiety-induced inhibition of Cu diffusion, promotion of high-conductivity interfacial nickel telluride formation, and mercaptan-induced reduction of Bi₂Te₃ surface oxides. Our findings should enable incorporating nanomolecular layers with appropriately chosen terminal moieties in thermoelectric device metallization schemes without metal diffusion barriers.