Beschreibung:
<jats:title>Abstract</jats:title><jats:p>A consecutive three‐component Heck‐Knoevenagel synthesis of phenothiazinyl merocyanines was developed by statistical design of experiments (DoE) and Bayesian optimization furnishing nine red orange dyes starting from heteroaryl halides, acrolein and ethyl cyanoacetate. Besides scrutinizing the electronic properties of these merocyanines by cyclic voltammetry, absorption and emission spectroscopy, and (TD)DFT calculations their saponified carboxylic acids were employed in dye‐sensitized solar cell (DSSC) experiments showing promising solar cell performances with relative efficiencies of up to 93 % compared to the standard ruthenium dye <jats:bold>N3</jats:bold>.</jats:p>