Synthesis And Crystal Structures Of New BODIPY Dyes

Small molecular photovoltaic materials, owing to their distinct chemicalstructures, easier purification, and well-reproducible synthesis, have attractedconsiderable attention in recent years. Furthermore, the structure-propertyrelationships of these materials are better understandable in comparison withpolymeric materials, indicating a better tenability of their properties. In terms ofprocess ability, vacuum deposition as well as solution process can be used for smallmolecular materials in device preparation.BODIPY dyes are a class of new functional materials developed nearly twodecades and have been widely used in various fields. Especially, thelong-wavelength BODIPY compounds as an electron donor have prospects ofapplication in solar cells.In this work, we use pyrrole and2-methylpyrrole as raw materials, thiomethyl,phenyl, and benzyl as substituents, to synthesized a series of BODIPY dyes. Thenthrough iodination and bromination, we obtained the compounds bromo and iodoBODIPY derivatives intermediates for further synthesis of the long-wavelengthsmall molecule BODIPY functional dyes. Finally, tetra-thiophene substitutedBODIPY small molecular functional dyes was obtained with Stille coupling reaction.With the characterizations, we had a further discussion about the reactionmechanism, as well as the compounds’ nature. X-ray diffraction shows structures ofthe BODIPY dyes and the substitution mechanism; The UV-Vis absorption spectrumshows the absorption wavelength of BODIPY derivatives is increased whensubstituted by iodide and thiophene. Wherein the tetra-thiophene substitutedBODIPY dye’s maximum absorption wavelength is632nm, also it has a broaderabsorption range with a strong absorption from550nm to680nm, and is thereforeexpected to be ideal for small molecules applied in organic solar cell material.