Specifics of ITO properties deposited on cerium-doped glass for space-grade solar cells

TL;DR

This study investigates how the properties of ITO thin films vary when deposited on cerium-doped glass compared to standard glass, revealing substrate-induced differences crucial for space-grade solar cell applications.

Contribution

It provides detailed analysis of ITO properties on Ce-glass, highlighting substrate effects on strain, transparency, and electrical characteristics relevant for space photovoltaics.

Findings

ITO on Ce-glass shows higher compressive strain and altered stoichiometry.

Reduced transparency and charge carrier concentration in ITO on Ce-glass.

Increased Hall mobility but decreased overall conductivity due to substrate interactions.

Abstract

Ce-doped glass is a well-established solution for ultraviolet and ionizing radiation shielding of solar cells in space. Traditionally, Ce-glass protected Si or III-V based devices as an overlaying cap. However, for emerging photovoltaics such as halide perovskites, thin Ce-glass coated with transparent conductive layers could serve as a lightweight carrier with an electrode. While indium-tin oxide (ITO) is widely used in solar cells for charge collection, its optical, structural, and electrical properties depend on the substrate quality. In this work, we demonstrated significant differences in properties of ITO deposited on Ce-glass (100 micron thick) compared to standard soda lime glass. ITO on Ce-glass exhibited pronounced compressive strain because of higher oxygen vacancy concentrations, reduced transparency and charge carrier concentration (10^19 cm-3) resulting from altered stoichiometry. Electrical analysis showed increased Hall mobility (66 cm2V-1s-1) but decreased conductivity due to excess tin incorporation. These specific ITO features originated from inelastic collisions with the substrate during deposition. Variations in wettability and surface potential underscore substrate-induced differences critical for developing optimized ITO coatings for space-grade photovoltaics.