TY - JOUR
T1 - Rational design of hybridized local and charge transfer emitters towards high-performance fluorescent blue OLEDs
AU - Wang, Shuxin
AU - Li, Hanlin
AU - Song, Zhen
AU - Jiang, He
AU - Zhang, Xiandi
AU - Tsang, Chui Shan
AU - Liu, Quanlin
AU - Lee, Lawrence Yoon Suk
AU - Ma, Dongge
AU - Wong, Wai Yeung
N1 - Funding Information:
We acknowledge the National Key R&D Program of China (2022YFE0104100), ITC Guangdong-Hong Kong Technology Cooperation Funding Scheme (TCFS) (GHP/038/19GD), CAS-Croucher Funding Scheme for Joint Laboratories (ZH4A), the Hong Kong Research Grants Council (PolyU 15305320), Fundamental Research Funds for the Central Universities (QNXM20210022), the Hong Kong Polytechnic University, Miss Clarea Au for the Endowed Professorship in Energy (847S) and Research Institute for Smart Energy (CDAQ) for financial support. We thank Limin Zhang for help with the X-ray crystal structure analysis.
Publisher Copyright:
© 2023 The Royal Society of Chemistry.
PY - 2023/6/28
Y1 - 2023/6/28
N2 - Hybridized local and charge-transfer (HLCT) emitters are promising for the realization of high-performance blue organic light-emitting diodes (OLEDs). However, the rational design of efficient HLCT emitters remains challenging. Here, we present two blue emitters (TAP1 and TAP2) with the HLCT state through the construction of D-π-A molecules. Theoretical calculations reveal the large overlap and partial separation of “hole” and “particle” orbitals for S1 excited states, demonstrating the HLCT nature of the emitters. Together with the clear solvatochromic phenomenon, we propose that introducing the π-conjugated anthracene unit into an appropriate donor-acceptor segment is an effective strategy to finely regulate the locally excited and charge transfer components and construct versatile HLCT emitters. Employing TAP2 and TAP1 as emitters, the blue OLEDs exhibit good color purity, high efficiency, and extremely low efficiency roll-offs with Commission internationale de l’éclairage coordinates of, respectively, (0.14, 0.10) and (0.15, 0.11), narrow full width at half maximum values of 45 nm and 52 nm, maximum external quantum efficiency values of 5.53% and 5.16%, and efficiency roll-off values of 0.5% and 1% at the practical brightness of 1000 cd m−2. By virtue of the transient photoluminescence decay curves, excited state energy levels and natural transition orbital analysis, we classify that the reverse intersystem crossing at high-lying excited states from T2 to S1 serves as an efficient approach to harvest triplet excitons and thus boost the exciton utilization efficiency. The superior properties of HLCT emitters in this work provide inspiration for the rational design of promising materials for high-performance blue OLEDs.
AB - Hybridized local and charge-transfer (HLCT) emitters are promising for the realization of high-performance blue organic light-emitting diodes (OLEDs). However, the rational design of efficient HLCT emitters remains challenging. Here, we present two blue emitters (TAP1 and TAP2) with the HLCT state through the construction of D-π-A molecules. Theoretical calculations reveal the large overlap and partial separation of “hole” and “particle” orbitals for S1 excited states, demonstrating the HLCT nature of the emitters. Together with the clear solvatochromic phenomenon, we propose that introducing the π-conjugated anthracene unit into an appropriate donor-acceptor segment is an effective strategy to finely regulate the locally excited and charge transfer components and construct versatile HLCT emitters. Employing TAP2 and TAP1 as emitters, the blue OLEDs exhibit good color purity, high efficiency, and extremely low efficiency roll-offs with Commission internationale de l’éclairage coordinates of, respectively, (0.14, 0.10) and (0.15, 0.11), narrow full width at half maximum values of 45 nm and 52 nm, maximum external quantum efficiency values of 5.53% and 5.16%, and efficiency roll-off values of 0.5% and 1% at the practical brightness of 1000 cd m−2. By virtue of the transient photoluminescence decay curves, excited state energy levels and natural transition orbital analysis, we classify that the reverse intersystem crossing at high-lying excited states from T2 to S1 serves as an efficient approach to harvest triplet excitons and thus boost the exciton utilization efficiency. The superior properties of HLCT emitters in this work provide inspiration for the rational design of promising materials for high-performance blue OLEDs.
UR - http://www.scopus.com/inward/record.url?scp=85151038323&partnerID=8YFLogxK
U2 - 10.1039/d2tc05554f
DO - 10.1039/d2tc05554f
M3 - Journal article
AN - SCOPUS:85151038323
SN - 2050-7526
JO - Journal of Materials Chemistry C
JF - Journal of Materials Chemistry C
ER -