Evolutionary de novo design of phenothiazine derivatives for dye-sensitized solar cells

Traditional approaches for improving the photovoltaic performance of dye-sensitized solar cells (DSSCs) have mainly relied on judicious molecular design and device level modifications. Such schemes, however, are bound by costly and time-consuming synthesis procedures. In this paper, we demonstrate the efficacy of an alternative approach based on in silico evolutionary de novo design of novel dye structures with improved DSSC power conversion efficiency (PCE) values. Because the PCE, cannot as yet be directly computed from first principles, the evolutionary fitness function utilizes predictive structure-property relationship (QSPR) models calibrated from empirical data. Our design approach is applied to phenothiazine-based dye sensitizers. The chemical structure space is explored using a genetic algorithm that systematically assembles molecules from fragments in a synthetically tractable manner. Five novel phenothiazine dyes are proposed using our approach where all have predicted PCE values above 9%.