Improving the Accuracy of Excited-State Simulations of BODIPY and Aza-BODIPY Dyes with a Joint SOS-CIS(D) and TD-DFT Approach
Résumé
BODIPY and aza-BODIPY dyes constitute two key families of org. dyes with applications in both materials science and biol. Previous attempts aiming to obtain accurate theor. ests. of their optical properties, and in particular of their 0-0 energies, have failed. Here, using time-dependent d. functional theory (TD-DFT), CI singles with a double correction [CIS(D)], and its scaled-opposite-spin variant [SOS-CIS(D)], the authors detd. the 0-0 energies as well as the vibronic shapes of both the absorption and emission bands of a large set of fluoroborates. Indeed, the authors have selected 47 BODIPY and 4 aza-BODIPY dyes presenting diverse chem. structures. TD-DFT yields a rather large mean signed error between the exptl. and theor. 0-0 energies with a systematic overshooting of the transition energies (by ∼0.4 eV). This error is reduced to ∼0.2 [0.1] eV when the TD-DFT 0-0 energies are cor. with vertical CIS(D) [SOS-CIS(D)] energies. For BODIPY and aza-BODIPY dyes, both CIS(D) and SOS-CIS(D) clearly outperform TD-DFT. The present computational protocol allows accurate data to be obtained for the most relevant properties, i.e., 0-0 energies and optical band shapes.