A Lewis acid-base chemistry approach towards narrow bandgap dye molecules

摘要: Abstract Although it usually involves troublesome and time-consuming synthesis work, molecular structure tailoring has been the mainstream tool to adjust optical absorption bandgap of organic semiconductors. Herein, we provided a convenient feasible method prepare narrow small-molecule semiconductors by Lewis acid-base chemistry was adjusted stoichiometry reactions. In this three pyridine capped diketopyrrolopyrrole (DPP) molecules, i.e., DPPPy-Ph-F, DPPPy-Ph-3F, DPPPy-Py-F, with medium were synthesized coordinate acid B(C6F5)3 (BCF). By coordinating BCF, as demonstrated 1H, 19F, 11B NMR spectra, bandgaps these DPP molecules depressed largely. For two units flanking symmetrically, 2 eq BCF converted nitrogens stoichiometrically adducts, along bands red-shifted (1.89 vs. 1.80 eV). flanked trifluorobenzene capped, adding unable convert adducts completely, due strong electron-drawing ability substituent on pyridine, reducing its basicity. After excess nitrogens, DPPPy-Ph-3F also decreased from 1.92 eV 1.84 eV. four flanked, 4 required bind nitrogens. Accordingly, red-shift depression (1.96 1.75 eV) for DPPPy-Py-F most striking among molecules.