TY - JOUR
T1 - Chromenopyrazole-Based Bipolar Blue Host Materials for Highly Efficient Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes
AU - Godumala, Mallesham
AU - Choi, Suna
AU - Park, Seo Yeon
AU - Cho, Min Ju
AU - Kim, Hyung Jong
AU - Ahn, Dae Hyun
AU - Moon, Ji Su
AU - Kwon, Jang Hyuk
AU - Choi, Dong Hoon
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea (NRF2015R1A2A1A05001876) and by the Key Research Institute Program (NRF20100020209). D. H. Choi particularly thanks for the support from LG display Co. Limited (2017−2018). It was also supported by a Korea University Grant (2017-2018).
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/8/14
Y1 - 2018/8/14
N2 - New electron-acceptor cores are necessary for developing highly efficient bipolar hosts, particularly for blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs). Herein, chromenopyrazole (CP) was used for the first time as an electron-acceptor core to design and synthesize two novel blue bipolar hosts, viz., 8-(9H-carbazol-9-yl)-3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-one (CzCP) and 8-(9H-[3,9′-bicarbazol]-9-yl)-3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-one (2CzCP). The influence of donor strength on the photophysical, electrochemical, and electroluminescent performances was systematically investigated. CzCP and 2CzCP both maintain high triplet energy (∼3.0 eV), appropriate highest occupied and lowest unoccupied energy levels (HOMO/LUMO), and bipolar nature. Consequently, OLEDs containing CzCP as a host in the emissive layer exhibited state-of-the-art performance with external quantum efficiency of 27.9% and CIE color coordinates of (0.15, 0.21), thus achieving excellent performance among all reported blue host materials in TADF-OLEDs. This work highlights the importance of the CP unit in developing new host materials and paves the way for the realization of high-efficiency blue TADF-OLEDs.
AB - New electron-acceptor cores are necessary for developing highly efficient bipolar hosts, particularly for blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs). Herein, chromenopyrazole (CP) was used for the first time as an electron-acceptor core to design and synthesize two novel blue bipolar hosts, viz., 8-(9H-carbazol-9-yl)-3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-one (CzCP) and 8-(9H-[3,9′-bicarbazol]-9-yl)-3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-one (2CzCP). The influence of donor strength on the photophysical, electrochemical, and electroluminescent performances was systematically investigated. CzCP and 2CzCP both maintain high triplet energy (∼3.0 eV), appropriate highest occupied and lowest unoccupied energy levels (HOMO/LUMO), and bipolar nature. Consequently, OLEDs containing CzCP as a host in the emissive layer exhibited state-of-the-art performance with external quantum efficiency of 27.9% and CIE color coordinates of (0.15, 0.21), thus achieving excellent performance among all reported blue host materials in TADF-OLEDs. This work highlights the importance of the CP unit in developing new host materials and paves the way for the realization of high-efficiency blue TADF-OLEDs.
UR - http://www.scopus.com/inward/record.url?scp=85049643448&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.8b01207
DO - 10.1021/acs.chemmater.8b01207
M3 - Article
AN - SCOPUS:85049643448
SN - 0897-4756
VL - 30
SP - 5005
EP - 5012
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 15
ER -