Passivation and Carrier Lifetime of Ultra-Thin Film Silicon with Tandem Niobium Oxide and Attached Organosilane

Tandem junction solar cells with silicon and a dissimilar absorber material pose unique challenges for minimizing interfacial defects between those absorbers. Organic layers would enable flexible, soft, carrier-selective contacts, but silane attachment chemistry to silicon presents its own interfacial defects that must be minimized. A focus on silicon substrates in tandem with deposited niobium oxides, and silane-based organic layers has potential to minimize electronic defects and improve efficiencies. Here, atomic-layer deposition (ALD) deposited ultra-thin niobium oxide layers and wet-chemical processing yielded organosilane monolayers on silicon substrates. Photoelectron spectroscopy quantified surface coverages while microwave-based transient photoconductivity measurements established carrier recombination velocities for these surfaces. Ongoing studies are quantifying the resulting solar energy conversion of the resulting soft-interface tandem junction solar cells.