Photovoltaic cells based on organic semiconductors and/or organic light harvesters (HOPV) are potentially extremely inexpensive, but their efficiency and stability are still limited when compared to inorganic crystalline solar cells. Among them, Dye-sensitized Solar Cells (DSCs) represent a promising and emerging technology because of their advantages like simple fabrication process and low environmental impact. In recent years the research has focused on the understanding of the photovoltaic processes and the improvement of the photoconversion efficiencies, currently around 12-15%[1,2]. Despite these continuos advances, DSCs are not yet commercialized on large-scale, because they suffer of troubles in long-term stability, especially with organic and NIR sensitizers[3]. In fact, the cells are subjected to undesirable phenomena, i.e. photodegradation of the dye anchored on semiconductor, leakage of the electrolyte, diffusion of pollutants from the outside and corrosion of some components. Another problem is due to the difficulty in realizing devices able to guarantee high photovoltaic performances with reliable reproducibility. The reason is that the cells are assembled with different and heterogeneous layers (FTO/TiO2/dye/electrolyte/Pt-FTO), each one affected by intrinsic variability; moreover the layers influence each other and this increases exponentially in cells with large active area, like modules and panels for commercial applications. The present work provides the development of a fast and facile method that enabled us to study the photostability and the photovoltaic efficiency of a series of NIR sensitizers, by correlating the results both to the structural characteristic of the molecule and to the dipping condition. However, this work cannot be conducted with univariate approach, observing single factors one by one, like most of the research on DSCs has been conducted so far. In fact, ranging one variable at a time (OVAT), it results very difficult to understand and predict the possible synergistic effects, due to the interactions between the variables themselves. Therefore, this research has been conducted with a multivariate approach, in particular through chemometrics analysis, that allows to evaluate all variables. The main idea is to optimize each stage of the production process of the cell in order to obtain a significant improvement in reproducibility, long-term stability and efficiency.
Multivariate approaches to improve performance and stability of NIR sensitizers in Dye-sensitized Solar Cells
GALLIANO, SIMONE;SACCONE, DAVIDE;BARBERO, Nadia;QUAGLIOTTO, Pierluigi;BAROLO, CLAUDIA;VISCARDI, Guido
2014-01-01
Abstract
Photovoltaic cells based on organic semiconductors and/or organic light harvesters (HOPV) are potentially extremely inexpensive, but their efficiency and stability are still limited when compared to inorganic crystalline solar cells. Among them, Dye-sensitized Solar Cells (DSCs) represent a promising and emerging technology because of their advantages like simple fabrication process and low environmental impact. In recent years the research has focused on the understanding of the photovoltaic processes and the improvement of the photoconversion efficiencies, currently around 12-15%[1,2]. Despite these continuos advances, DSCs are not yet commercialized on large-scale, because they suffer of troubles in long-term stability, especially with organic and NIR sensitizers[3]. In fact, the cells are subjected to undesirable phenomena, i.e. photodegradation of the dye anchored on semiconductor, leakage of the electrolyte, diffusion of pollutants from the outside and corrosion of some components. Another problem is due to the difficulty in realizing devices able to guarantee high photovoltaic performances with reliable reproducibility. The reason is that the cells are assembled with different and heterogeneous layers (FTO/TiO2/dye/electrolyte/Pt-FTO), each one affected by intrinsic variability; moreover the layers influence each other and this increases exponentially in cells with large active area, like modules and panels for commercial applications. The present work provides the development of a fast and facile method that enabled us to study the photostability and the photovoltaic efficiency of a series of NIR sensitizers, by correlating the results both to the structural characteristic of the molecule and to the dipping condition. However, this work cannot be conducted with univariate approach, observing single factors one by one, like most of the research on DSCs has been conducted so far. In fact, ranging one variable at a time (OVAT), it results very difficult to understand and predict the possible synergistic effects, due to the interactions between the variables themselves. Therefore, this research has been conducted with a multivariate approach, in particular through chemometrics analysis, that allows to evaluate all variables. The main idea is to optimize each stage of the production process of the cell in order to obtain a significant improvement in reproducibility, long-term stability and efficiency.
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