Optoelectronic characteristics of as-deposited, annealed and I2 – Treated thin films of newly synthesized organic dye based on pyrrolo[2,3-b]pyrrole

Abstract

Novel heterocyclic dyes were synthesized by attaching different electron-rich aromatics to the pyrrolo[2,3-b]pyrrole system by microwave irradiation system provided with condensation unit. The final push-pull conjugated dyes were yielded by azo coupling of PPY with aniline, 1-naphthylamine and N,N-dimethylaniline. Thin films of compound 3 have been chosen and prepared using thermal evaporation technique and investigated by FTIR and UV – VIS – NIR spectroscopy. Annealing out of PPY films at relatively low temperature (≤100 ​°C) for 3–6 ​min has been proved to notably reduce the energy gap and enhance both absorption and refractive indices. They manifested a fast response and high sensitivity toward iodine vapor with a low recovery time indicating a reversibility of iodine adsorption process.

Keywords

• Pyrrolo[2,3-b]pyrrole
• Microwave irradiation
• Thin films
• Thermal evaporation
• Optical properties
• Iodine adsorption