Reliable Prediction with Tuned Range-Separated Functionals of the Singlet–Triplet Gap in Organic Emitters for Thermally Activated Delayed Fluorescence

The thermally activated delayed fluorescence (TADF) mechanism has recently attracted significant interest in the field of organic light-emitting diodes (OLEDs). TADF relies on the presence of a very small energy gap between the lowest singlet and triplet excited states. Here, we demonstrate that time-dependent density functional theory in the Tamm–Dancoff approximation can be very successful in calculations of the lowest singlet and triplet excitation energies and the corresponding singlet–triplet gap when using nonempirically tuned range-separated functionals. Such functionals provide very good estimates in a series of 17 molecules used in TADF-based OLED devices with mean absolute deviations of 0.15 eV for the vertical singlet excitation energies and 0.09 eV [0.07 eV] for the adiabatic [vertical] singlet–triplet energy gaps as well as low relative errors and high correlation coefficients compared to the corresponding experimental values. They significantly outperform conventional functionals, a feature which is rationalized on the basis of the amount of exact-exchange included and the delocalization error. The present work provides a reliable theoretical tool for the prediction and development of novel TADF-based materials with low singlet–triplet energetic splittings

Reaction Inclusion Performance of AGPathFinder under different parameter settings.

<p>Reaction Inclusion Performance of AGPathFinder under different parameter settings.</p

Computed pathways for L-serine biosynthesis: <i>r</i>₁, <i>r</i>₂, <i>r</i>₃ and <i>r</i>₄.

<p>Rectangles represent reaction edges, and the data in parentheses denote the value of reaction and the compound similarity respectively.</p

Conserved atomic group transfer.

<p>Conserved atomic group transfer in chemical reactions R02722 and R00674 in KEGG RPAIR database. R02722: L-serine+Indoleglycerol phosphate < = > L-tryptophan + D-Glyceraldehyde 3-phosphate + H₂O. R00674: L-serine + Indole < = > L-tryptophan + H₂O. The arrows denote mapping of atoms from C00065 to C00078 via R02722 and R00674. The partition encircled with dotted line is the conserved atomic group transferred from the start compound during the pathway inference. Atom mapping entry RP00587 contains reactions R00674 and R02722. Hydrogens and their associated bonds are not shown.</p

<i>C-1tomany</i> and <i>CR-1tomany</i> of one-to-many alignment results for <i>hsa</i>-<i>atc</i>.

<p><i>C-1tomany</i> and <i>CR-1tomany</i> of one-to-many alignment results for <i>hsa</i>-<i>atc</i>.</p

<i>C-1tomany</i> and <i>CR-1tomany</i> of one-to-many alignment results for <i>eco</i>-<i>atc</i>.

<p><i>C-1tomany</i> and <i>CR-1tomany</i> of one-to-many alignment results for <i>eco</i>-<i>atc</i>.</p

<i>C-1tomany</i> and <i>CR-1tomany</i> of one-to-many alignment results for <i>mmu</i>-<i>atc</i>.

<p><i>C-1tomany</i> and <i>CR-1tomany</i> of one-to-many alignment results for <i>mmu</i>-<i>atc</i>.</p

Computed pathways for L-Methionine biosynthesis: <i>r</i>₁, <i>r</i>₂, <i>r</i>₃, <i>r</i>₄ and <i>r</i>₅.

<p>Round rectangles represent compound nodes, rectangles represent reaction edges, and the data in parentheses denote the value of reaction and compound similarity respectively. “*” means that the Gibbs free energy of the corresponding reaction is not available.</p

<i>ELCCS</i> of one-to-one alignment results for <i>hsa-eco</i> and <i>hsa-atc</i>.

<p><i>ELCCS</i> of one-to-one alignment results for <i>hsa-eco</i> and <i>hsa-atc</i>.</p

Sample alignments.

<p>The upper reactions are a part of the pathways of <i>atc</i>, whereas the lower reactions are a part of the pathways of <i>eco</i>. Reactions are represented by their KEGG identifiers. Enzymes are shown in EC numbers. The compounds are depicted by small circles. (a) One-to-one reaction mappings extracted from the alignment of the metabolic pathways of lysine biosynthesis in <i>atc</i> and <i>eco</i>. (b) A one-to-many reaction mapping extracted from the alignment of the metabolic pathways of Glyoxylate and dicarboxylate metabolism in <i>atc</i> and <i>eco</i>. (c) A many-to-many reaction mapping extracted from the alignment of the metabolic pathways of Glycolysis in <i>atc</i> and <i>eco</i>.</p