Balanced Energy Gaps as a Key Design Rule for Solution-Phase Organic Room Temperature Phosphorescence

Simon Paredis, Tom Cardeynaels, Suman Kuila, Jasper Deckers, Melissa Van Landeghem, Koen Vandewal, Andrew Danos, Andrew P. Monkman, Benoît Champagne, Wouter Maes

Research output: Contribution to journalArticlepeer-review


Metal-free organic emitters that display solution-phase room temperature phosphorescence (sRTP) remain exceedingly rare. Here, we investigate the structural and photophysical properties that support sRTP by comparing a recently reported sRTP compound (BTaz−Th−PXZ) to two novel analogous materials, replacing the donor group by either acridine or phenothiazine. The emissive triplet excited state remains fixed in all three cases, while the emissive charge-transfer singlet states (and the calculated paired charge-transfer T2 state) vary with the donor unit. While all three materials show dominant RTP in film, in solution different singlet-triplet and triplet-triplet energy gaps give rise to triplet-triplet annihilation followed by weak sRTP for the new compounds, compared to dominant sRTP throughout for the original PXZ material. Engineering both the sRTP state and higher charge-transfer states therefore emerges as a crucial element in designing emitters capable of sRTP.

Original languageEnglish
Article numbere202301369
JournalChemistry - A European Journal
Issue number42
Publication statusPublished - 26 Jul 2023


  • donor-acceptor fluorophores
  • energy gap tuning
  • room temperature phosphorescence
  • time-resolved spectroscopy


Dive into the research topics of 'Balanced Energy Gaps as a Key Design Rule for Solution-Phase Organic Room Temperature Phosphorescence'. Together they form a unique fingerprint.

Cite this