Low Temperature Solution-Based Treatment for Highly Passivated Si/TiO₂ Heterojunction

Abstract

Thin film-based second and third generation photovoltaics (PVs) are avidly investigated for their potential for utility scale applications. Organic thin film (PEDOT) and silicon-based PVs are shown to have moderate device efficiency. To further improve efficiency, silicon is sandwiched between thin films of PEDOT and TiO₂. Thin films of TiO₂ synthesized at 100°C have been shown to make efficient (~12%) PEDOT/Si/TiO₂-based PVs; TiO₂ functions as a holeblocker. Lower efficiencies of the PVs than predicted by theory is attributed to poor passivation of the Si/TiO₂ interface. To improve the interface passivation, the Si/TiO₂ interface is treated under various chemical conditions. One such treatment yielded very high level of passivation (SRV ~ 15 cm/s).

Keywords: Heterojunction, Reverse Saturation Current, Surface Recombination Velocity, Titanium tetra (tert-butoxide), X-Ray Photoelectron Spectroscopy