TY - JOUR
T1 - Organic Long-Persistent Luminescence from a Thermally Activated Delayed Fluorescence Compound
AU - Li, Wenbo
AU - Li, Zhaoning
AU - Si, Changfeng
AU - Wong, Michael Y.
AU - Jinnai, Kazuya
AU - Gupta, Abhishek Kumar
AU - Kabe, Ryota
AU - Adachi, Chihaya
AU - Huang, Wei
AU - Zysman-Colman, Eli
AU - Samuel, Ifor D.W.
N1 - Publisher Copyright:
© 2020 The Authors. Published by Wiley-VCH GmbH
PY - 2020/11/12
Y1 - 2020/11/12
N2 - Organic long-persistent luminescence (OLPL) is one of the most promising methods for long-lived-emission applications. However, present room-temperature OLPL emitters are mainly based on a bimolecular exciplex system which usually needs an expensive small molecule such as 2,8-bis(diphenyl-phosphoryl)dibenzo[b,d]thiophene (PPT) as the acceptor. In this study, a new thermally activated delayed fluorescence (TADF) compound, 3-(4-(9H-carbazol-9-yl)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile (CzPhAP), is designed, which also shows OLPL in many well-known hosts such as PPT, 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), and poly(methyl methacrylate) (PMMA), without any exciplex formation, and its OLPL duration reaches more than 1 h at room temperature. Combining the low cost of PMMA manufacture and flexible designs of TADF molecules, pure organic, large-scale, color tunable, and low-cost room-temperature OLPL applications become possible. Moreover, it is found that the onset of the 77 K afterglow spectra from a TADF-emitter-doped film is not necessarily reliable for determining the lowest triplet state energy level. This is because in some TADF-emitter-doped films, optical excitation can generate charges (electron and holes) that can later recombine to form singlet excitons during the phosphorescence spectrum measurement. The spectrum taken in the phosphorescence time window at low temperature may consequently consist of both singlet and triplet emission.
AB - Organic long-persistent luminescence (OLPL) is one of the most promising methods for long-lived-emission applications. However, present room-temperature OLPL emitters are mainly based on a bimolecular exciplex system which usually needs an expensive small molecule such as 2,8-bis(diphenyl-phosphoryl)dibenzo[b,d]thiophene (PPT) as the acceptor. In this study, a new thermally activated delayed fluorescence (TADF) compound, 3-(4-(9H-carbazol-9-yl)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile (CzPhAP), is designed, which also shows OLPL in many well-known hosts such as PPT, 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), and poly(methyl methacrylate) (PMMA), without any exciplex formation, and its OLPL duration reaches more than 1 h at room temperature. Combining the low cost of PMMA manufacture and flexible designs of TADF molecules, pure organic, large-scale, color tunable, and low-cost room-temperature OLPL applications become possible. Moreover, it is found that the onset of the 77 K afterglow spectra from a TADF-emitter-doped film is not necessarily reliable for determining the lowest triplet state energy level. This is because in some TADF-emitter-doped films, optical excitation can generate charges (electron and holes) that can later recombine to form singlet excitons during the phosphorescence spectrum measurement. The spectrum taken in the phosphorescence time window at low temperature may consequently consist of both singlet and triplet emission.
KW - afterglow
KW - charge recombination
KW - charge separation
KW - long-persistent luminescence (LPL)
KW - organic long-persistent luminescence (OLPL)
KW - thermally activated delayed fluorescence (TADF)
UR - http://www.scopus.com/inward/record.url?scp=85092134701&partnerID=8YFLogxK
U2 - 10.1002/adma.202003911
DO - 10.1002/adma.202003911
M3 - 文章
C2 - 33029892
AN - SCOPUS:85092134701
SN - 0935-9648
VL - 32
JO - Advanced Materials
JF - Advanced Materials
IS - 45
M1 - 2003911
ER -