Confinement of Long‐Lived Triplet Excitons in Organic Semiconducting Host–Guest Systems

• Published in: Advanced functional materials Vol. 27; no. 40
• Main Authors: Notsuka, Naoto, Kabe, Ryota, Goushi, Kenichi, Adachi, Chihaya
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 26.10.2017
• Subjects: Confining; Deactivation; electroluminescence; Emitters; Energy gap; energy transfer; Excitation; Excitons; Materials science; nonradiative decay; Organic chemistry; organic semiconductors; Phosphorescence; Supramolecular compounds; System effectiveness
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201703902

Long‐lived triplet excitons on organic molecules easily deactivate at room temperature because of the presence of thermally activated nonradiative pathways. This study demonstrates long‐lived phosphorescence at room temperature resulting from suppression of the nonradiative deactivation of triplet excitons in conventional organic semiconducting host–guest systems. The nonradiative deactivation pathway strongly depends on the triplet energy gap between the guest emitting molecules and the host matrices. The triplet energy gap required to confine the long‐lived triplet excitons (≈0.5 eV) is much larger than that of conventional host–guest systems for phosphorescent emitters. By effectively confining the triplet excitons, this study demonstrates long‐lived room‐temperature phosphorescence under optical and electrical excitation. The nonradiative deactivation pathway of long‐lived room‐temperature phosphorescence is strongly affected by the triplet energy gap between the guest emitting molecules and the host matrices in organic semiconducting host–guest systems. The triplet energy gap required to confine the long‐lived triplet excitons (≈0.5 eV) is much larger than that of conventional triplet exciton harvesting host–guest systems.