The synthesis of two new star-shaped organic small molecules with a truxene
core, molecules 11 and 12, were carried out. They varied in sidechain length with
molecule 11 having hexahexyl and molecule 12 having hexadodecyl side chains.
The physical and photovoltaic properties were measured and characterized. Both
molecules showed activity in UV-visible light and electrochemical processes.
Molecule 11 had optical and electrochemical HOMO-LUMO energy gaps of 2.15
and 2.45 eV, respectively, while molecule 12 had 2.12 and 2.50 eV gaps.
Photovoltaic device fabrication and testing revealed bifunctional acceptor-donor
properties of the molecules in bulk-heterojunction organic solar cells. The device
PCEs for molecule 11 were 0.003% and 0.002%, while the PCEs for 12 were 0.004%
and 0.03%. This improvement was attributed to the ease of processing and selfassembly
induced by the long alkyl side chains of molecule 12.
Keywords: Synthesis; Star-shape; Truxene; Organic small molecules; Solar cells
