Robust, Scalable Synthesis of the Bulky Hagfeldt Donor for Dye-Sensitized Solar Cells

The bulky triarylamine group commonly referred to as the "Hagfeldt donor" is a key building block found in many of the organic dyes used in dye-sensitized applications such as dye-sensitized solar cells (DSCs). This building block has gained popularity owing to its presence in many of the best-performing DSC devices reported to date, which use dyes containing this donor group. The Hagfeldt donor provides a desirable 3-dimensional structure that aids in surface protection of electrons injected into the semiconductor from oxidants in the electrolyte, allowing for record-setting cobalt- and copper-based redox shuttles to be utilized more frequently. However, the synthesis of this molecule has proven unreliable for many routes. This study concerns a novel, reliable and scalable five-step synthesis of the Hagfeldt donor.