• Lin, Yingsi
• Mcnab, Shona
• Patrick, Christopher E.
• Aldhahir, Isabel
• Bonilla, Ruy S.
• Altermatt, Pp
• Yu, Mingzhe
• Niu, Xinya

Abstract

The power conversion efficiency of solar cells is strongly impacted by an unwanted loss of charge carriers occurring at semiconductor surfaces and interfaces. Here the use of ion-charged oxide nanolayers to enhance the passivation of silicon surfaces via the field effect mechanism is reported. The first report of enhanced passivation from rubidium and cesium ion-charged oxide nanolayers is provided. The charge state and formation energy of ion-charged silicon dioxide are calculated from first principles. Ion embedding is demonstrated and exploited to control the interface population of carriers and minimize electron-hole pair recombination. The passivation quality directly improves with charge concentration, yet excess ions can produce detrimental interface states. An optimal ionic charge concentration of ≈1.5 × 1012 q cm−2 is deduced, and a recombination velocity and current density as low as 2.8 cm s−1 and 7.8 fA cm−2 are achieved at the Si-SiO2 interface. Maximized charge is shown to provide efficiency improvements as high as 0.7% absolute. This work provides a unique route to enhance passivation without compromising the film synthesis, thus retaining the antireflection and hydrogenation film properties. As such, ion-charged dielectrics provide complementary paths for surface and interface optimization in future single-junction and tandem solar cells.

Topics

• density
• impedance spectroscopy
• surface
• semiconductor
• Silicon
• current density
• power conversion efficiency
• Rubidium