On the Underlying Mechanism of Light-Induced Patterning of N719-Stained Photoanodes for "Photovoltaic Photographs"

TL;DR

This study investigates the physico-chemical mechanisms behind light-induced patterning in N719-stained photoanodes, revealing dye degradation pathways and the role of TiO2, to improve control and application of photovoltaic photographs.

Contribution

It provides detailed insights into the chemical degradation process of N719 dye and the role of TiO2 in light-induced patterning of dye-sensitized solar cells, advancing understanding of this novel technique.

Findings

TiO2 is crucial in the patterning process

N719 dye undergoes multi-step chemical degradation

Insights enable better control of light-induced patterning

Abstract

Recently, "photovoltaic photographs" were proposed as a creative application of photovoltaic technologies, relevant in fields such as architecture or the automotive industry. In this application an image is created by light-induced patterning of the photoactive layer, causing a local change in the appearance of the solar cell. In order to further develop this concept, it is crucial to elucidate the mechanism underlying these local changes. Here, UV-VIS and infrared spectroscopic techniques, as well as Gas Chromatography - Mass Spectrometry and time-of-flight secondary ion mass spectrometry, have been used to investigate the physico-chemical changes induced by this process in the photoactive layer of proof-of-concept photo-patterned dye-sensitized solar cells. We show that, for N719 photovoltaic photographs, TiO2 plays a crucial role and that the dye undergoes a multi-step chemical degradation, related to its isothiocyanate ligand. These insights are of importance for a better understanding of the photo-induced degradation of N719, a more substantiated control of the light-induced patterning process, and to design appropriate light-induced patterning techniques for other classes of solar cells.