Optimizing the Optical Properties of Tin Oxide Aerogels through Defect Passivation

TL;DR

This study investigates how post-synthesis treatments like annealing and peroxide passivation affect the optical properties of tin oxide aerogels, revealing that peroxide treatment effectively reduces defects and tunes the bandgap.

Contribution

It demonstrates that peroxide passivation can significantly lower the defect-related bandgap increase in tin oxide aerogels, providing a method to optimize their optical properties.

Findings

Annealing induces partial phase change but does not remove defects.

Peroxide passivation reduces defects and lowers the bandgap.

Defects are the main cause of increased bandgap in aerogels.

Abstract

Tin oxide aerogels were synthesized using an epoxide-assisted technique and characterized with Fourier transform infrared, X-ray diffraction, and UV-Vis to study the effects of post-synthesis annealing and peroxide treatment. While bulk tin oxide exhibits an optical bandgap of $3.6$ eV, its aerogel form often displays a larger apparent bandgap around $4.6$ eV due to defects. Our study reveals that annealing induces a partial phase change from SnO$_2$ to SnO, but is ineffective in removing defects. Conversely, peroxide passivation effectively lowers the bandgap and disorder levels, suggesting that dangling bonds are the primary cause of the increased bandgap in tin oxide aerogels. These findings offer insights for optimizing the optical properties of tin oxide aerogels for applications like solar cells.