Organic molecules with inverted singlet-triplet gaps
According to Hund’s multiplicity rule, the energy of the lowest excited triplet state (T1) is always lower than that of the lowest excited singlet state (S1) in organic molecules, resulting in a positive singlet-triplet energy gap (ΔEST). Therefore, the up-converted reverse intersystem crossing (RIS...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2022-08-01
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| Series: | Frontiers in Chemistry |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fchem.2022.999856/full |
| _version_ | 1798037012128727040 |
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| author | Jie Li Zhi Li Hui Liu Heqi Gong Jincheng Zhang Yali Yao Qiang Guo |
| author_facet | Jie Li Zhi Li Hui Liu Heqi Gong Jincheng Zhang Yali Yao Qiang Guo |
| author_sort | Jie Li |
| collection | DOAJ |
| description | According to Hund’s multiplicity rule, the energy of the lowest excited triplet state (T1) is always lower than that of the lowest excited singlet state (S1) in organic molecules, resulting in a positive singlet-triplet energy gap (ΔEST). Therefore, the up-converted reverse intersystem crossing (RISC) from T1 to S1 is an endothermic process, which may lead to the quenching of long-lived triplet excitons in electroluminescence, and subsequently the reduction of device efficiency. Interestingly, organic molecules with inverted singlet-triplet (INVEST) gaps in violation of Hund’s multiplicity rule have recently come into the limelight. The unique feature has attracted extensive attention in the fields of organic optoelectronics and photocatalysis over the past few years. For an INVEST molecule possessing a higher T1 with respect to S1, namely a negative ΔEST, the down-converted RISC from T1 to S1 does not require thermal activation, which is possibly conducive to solving the problems of fast efficiency roll-off and short lifetime of organic light-emitting devices. By virtue of this property, INVEST molecules are recently regarded as a new generation of organic light-emitting materials. In this review, we briefly summarized the significant progress of INVEST molecules in both theoretical calculations and experimental studies, and put forward suggestions and expectations for future research. |
| first_indexed | 2024-04-11T21:20:51Z |
| format | Article |
| id | doaj.art-f6b9e7568770419291733ab9e064b63d |
| institution | Directory Open Access Journal |
| issn | 2296-2646 |
| language | English |
| last_indexed | 2024-04-11T21:20:51Z |
| publishDate | 2022-08-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Chemistry |
| spelling | doaj.art-f6b9e7568770419291733ab9e064b63d2022-12-22T04:02:38ZengFrontiers Media S.A.Frontiers in Chemistry2296-26462022-08-011010.3389/fchem.2022.999856999856Organic molecules with inverted singlet-triplet gapsJie Li0Zhi Li1Hui Liu2Heqi Gong3Jincheng Zhang4Yali Yao5Qiang Guo6College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, ChinaCollege of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, ChinaCollege of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, ChinaCollege of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, ChinaCollege of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, ChinaSchool of Physics and Engineering Technology, Chengdu Normal University, Chengdu, ChinaCollege of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, ChinaAccording to Hund’s multiplicity rule, the energy of the lowest excited triplet state (T1) is always lower than that of the lowest excited singlet state (S1) in organic molecules, resulting in a positive singlet-triplet energy gap (ΔEST). Therefore, the up-converted reverse intersystem crossing (RISC) from T1 to S1 is an endothermic process, which may lead to the quenching of long-lived triplet excitons in electroluminescence, and subsequently the reduction of device efficiency. Interestingly, organic molecules with inverted singlet-triplet (INVEST) gaps in violation of Hund’s multiplicity rule have recently come into the limelight. The unique feature has attracted extensive attention in the fields of organic optoelectronics and photocatalysis over the past few years. For an INVEST molecule possessing a higher T1 with respect to S1, namely a negative ΔEST, the down-converted RISC from T1 to S1 does not require thermal activation, which is possibly conducive to solving the problems of fast efficiency roll-off and short lifetime of organic light-emitting devices. By virtue of this property, INVEST molecules are recently regarded as a new generation of organic light-emitting materials. In this review, we briefly summarized the significant progress of INVEST molecules in both theoretical calculations and experimental studies, and put forward suggestions and expectations for future research.https://www.frontiersin.org/articles/10.3389/fchem.2022.999856/fullinverted singlet-tripletdown conversionorganic light-emitting materialsreverse intersystem crossingthermal activated delayed fluorescence |
| spellingShingle | Jie Li Zhi Li Hui Liu Heqi Gong Jincheng Zhang Yali Yao Qiang Guo Organic molecules with inverted singlet-triplet gaps Frontiers in Chemistry inverted singlet-triplet down conversion organic light-emitting materials reverse intersystem crossing thermal activated delayed fluorescence |
| title | Organic molecules with inverted singlet-triplet gaps |
| title_full | Organic molecules with inverted singlet-triplet gaps |
| title_fullStr | Organic molecules with inverted singlet-triplet gaps |
| title_full_unstemmed | Organic molecules with inverted singlet-triplet gaps |
| title_short | Organic molecules with inverted singlet-triplet gaps |
| title_sort | organic molecules with inverted singlet triplet gaps |
| topic | inverted singlet-triplet down conversion organic light-emitting materials reverse intersystem crossing thermal activated delayed fluorescence |
| url | https://www.frontiersin.org/articles/10.3389/fchem.2022.999856/full |
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