Abstract
Bridged triphenylamine was chosen as the donor unit for metal-free organic sensitizers in dye-sensitized solar cells (DSSCs). The easily constructed alkene linkage between the donor and the spacer improves the molecule's delocalization and causes a large red shift in its absorption peaks. Planarization of the donor and the use of alkene linkage have proven powerful in extending the red light response of the sensitizer, leading to a significant enhancement in photocurrent density of the device. As a result, devices sensitized with target sensitizers LC-2 (η = 7.51%) and LC-3 (η = 8.00%) exhibited more than 70% efficiency increase over devices sensitized with the reference sensitizer LC-1 (η = 4.44%).