Field Effect Conductivities of P-I-N Heterostructure Films in Fuel Cells

Ionic conductivity enables the technologies of fuel cells, electrolysis cells, and batteries. However, the ambiguous origins of the extraordinary ionic conductivity impede its implementation in heterostructure films for the devices. Here, we disclosed that the extraordinary ionic and electronic conductivities come from field effect. We found in Ce_0.8Gd_0.2O_2-δ (CGO)/Zr_0.85Y_0.15O_2-δ (YSZ) heterostructures that the ionic conductivity of CGO layer (n-i conductor) and the electronic conductivity of YSZ layer (p-i conductor) exponentially increased with potential. The potential occurred from electron transfer and stoichiometric polarization in p-i-n junction. Field effect ionic conductivity contributed the major increment in the maximum power density. The results demonstrated field effect ionic and electronic conductivities, their dependences on heterostructures, and impacts on fuel cells.