Enhanced spin-orbit coupling driven by state mixing in organic molecules for OLED applications

Tzu Ting Huang, Elise Y. Li*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


We investigate the energy gap variation as well as spin-orbit coupling (SOC) integrals between various low-lying singlet and triplet excited states for a series of fluorescein derivatives. We find that when the electron-donating property of the substituent group on the benzene moiety of fluorescein is gradually increased, the charge transfer states are lowered in energy and a mixing with nearby ππ* or nπ* states occurs, which causes a twisting in the p orbital on the carbonyl group and a non-zero SOC integral between the originally non-coupled 1ππ* and 3ππ* states. We also find an enhancement of about 3–4 times in the SOC integrals upon sulfur substitution for the oxygen in the carbonyl groups, and that with substantial energy lowering in ππ* and especially in nπ* states, the SOC between the S1 state with energetically close triplet states is also increased significantly, signifying the possibility of enhanced phosphorescence or thermally-delayed fluorescence emission.

Original languageEnglish
Pages (from-to)311-317
Number of pages7
JournalOrganic Electronics
Publication statusPublished - 2016 Dec 1


  • Organic light-emitting diodes
  • Spin-orbit coupling
  • Thermally activated delayed fluorescence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • General Chemistry
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering


Dive into the research topics of 'Enhanced spin-orbit coupling driven by state mixing in organic molecules for OLED applications'. Together they form a unique fingerprint.

Cite this