Résumé
The recent emergence of the Internet of Things paved the way for the development of smart items and self-powered devices. This new approach for domotics induced a need for efficiently powering these appliances under low light conditions, which gave rise to indoor photovoltaics. Among all the existing technologies available, 3rd generation photovoltaics proved to be highly efficient for this purpose. DSSCs showed to be particularly interesting [1] as they are an excellent compromise between efficiency and processability. In consequence, the industrial development of DSSCs is growing more and more, bringing a necessity for fabricating DSSCs stable for long periods of time.SL9 and SL10 are two recently published dyes [2] that have demonstrated high Power Conversion Efficiency (PCE) in co-sensitized devices in indoor and outdoor conditions. In this work, these dyes were synthetised and characterized using NMR, HRMS, UV-Vis spectroscopy and cyclic voltammetry. They were then integrated in industrially processed DSSCs to evaluate their long-term stability and performance under white LED light. As a result, co-adsorbed SL9 and SL10 displayed high PCE at 1000 lux of more than 25% after 3000 hours, making them comparable to benchmark sensitizers. Even at 130 lux of illumination, more than 22% PCE was recorded, exceeding most of other commercially available technologies.Literature has shown that the preliminary adsorption of bufexamic acid on the photoanode allows to improve the dense packing of the sensitizer grafted on the surface of the mesoporous film of titania [2, 3]. This method was applied to SL9/SL10 co-sensitized cells and contributed to increase the JSC and fill factor by a few percent, which is consistent with previous findings.Finally, a set of SL9/SL10 cells with and without pre-adsorption were subjected to accelerated stability tests to evaluate the influence of the acid pre-adsorption on the stability of the cells. The cells were then monitored under white LED light at low and moderate intensity for 1000 hours. After leading several tests, there was no clear evidence of a detrimental effect after bufexamic acid treatment. Indeed, both typologies of cells demonstrated similar trends for the decrease of the VOC and JSC. We assume that while the density of the dye monolayer does have a positive effect on the quantity of light absorbed and converted, there is no evident related mechanism influencing the degradation of the cells overtime. This makes bufexamic acid pre-adsorption an excellent option for improving the cell efficiency without compromising the stability in the long run.