2,1,3-Benzothiadiazole Small Donor Molecules: A DFT Study, Synthesis, and Optoelectronic Properties.

We herein report the design and synthesis of small-donor molecules, 2,1,3-benzothiadiazole derivatives ( 2a - d ), by Stille or Suzuki reaction. The synthesized compounds were characterized by spectroscopic and electrochemical methods. The compounds 2a - d absorb the light in a wide range (the UV-green/yellow light ( 2c )) and emit from green to red/near IR light ( 2c ). Furthermore, these compounds show a narrow energy gap (1.75-2.38 eV), and high Ea values increasing for polymers, which prove their electron-donating nature and semiconductor properties. The measurements were enhanced by theoretical modeling.