TY - JOUR
T1 - Customized Orthogonal Solvent System with Various Hole-Transporting Polymers for Highly Reproducible Solution-Processable Organic Light-Emitting Diodes
AU - Je, Hyeondoo
AU - Cho, Seunguk
AU - Kwon, Na Yeon
AU - Lee, Dong Won
AU - Cho, Min Ju
AU - Choi, Dong Hoon
N1 - Funding Information:
The authors acknowledge financial support from the National Research Foundation (NRF) of Korea (nos. NRF2019R1A2C2002647 and NRF2019R1A6A1A11044070) and LG Display Co. Limited (Q1927051, 2020). They are grateful to Korea Basic Science Institute (KBSI) for allowing the use of MALDI-TOF MS instrument and Institute for Basic Science (IBS, Korea) for allowing them to obtain nuclear magnetic resonance data (NMR; Ascend 500, Bruker).
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/8/10
Y1 - 2022/8/10
N2 - Recently, various hosts and emitters for solution-processable thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) have been developed. However, a few studies have been conducted on hole transport materials (HTMs) with differentiated solubility characteristics for manufacturing multilayer OLEDs using a solution process. Here, three new hole transport (HT) styrene polymers, PICz, PPBCz, and PTPCz, were synthesized by radical polymerization. Each of the polymers exhibited increases in their highest occupied molecular orbital (HOMO) levels and better hole-transporting abilities than poly(9-vinylcarbazole) (PVK) as a reference HT polymer. Furthermore, the three HT polymers exhibited different solubilities in toluene. Therefore, it was not possible to use a toluene solution to prepare the emitting layer (EML). To overcome this problem, ethyl acetate (EA), in which the three HT polymers are insoluble, was used as an orthogonal solvent to prepare an EML solution. In EA-solution-processed green-emitting TADF-OLEDs, the three HT-polymer-based devices displayed somewhat low turn-on voltages of 2.8 V and high external quantum efficiencies (EQEs) of >23%. These values are superior to those of a device with a PVK-HT layer. In addition, the devices manufactured with the EA solution showed high-performance reproducibility owing to the stable formation of each layer. In this study, we removed the HTM solubility constraint by dramatically changing the solvent for preparing the EML solution and provided an efficient strategy for the fabrication of OLED devices via solution processes in the future.
AB - Recently, various hosts and emitters for solution-processable thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) have been developed. However, a few studies have been conducted on hole transport materials (HTMs) with differentiated solubility characteristics for manufacturing multilayer OLEDs using a solution process. Here, three new hole transport (HT) styrene polymers, PICz, PPBCz, and PTPCz, were synthesized by radical polymerization. Each of the polymers exhibited increases in their highest occupied molecular orbital (HOMO) levels and better hole-transporting abilities than poly(9-vinylcarbazole) (PVK) as a reference HT polymer. Furthermore, the three HT polymers exhibited different solubilities in toluene. Therefore, it was not possible to use a toluene solution to prepare the emitting layer (EML). To overcome this problem, ethyl acetate (EA), in which the three HT polymers are insoluble, was used as an orthogonal solvent to prepare an EML solution. In EA-solution-processed green-emitting TADF-OLEDs, the three HT-polymer-based devices displayed somewhat low turn-on voltages of 2.8 V and high external quantum efficiencies (EQEs) of >23%. These values are superior to those of a device with a PVK-HT layer. In addition, the devices manufactured with the EA solution showed high-performance reproducibility owing to the stable formation of each layer. In this study, we removed the HTM solubility constraint by dramatically changing the solvent for preparing the EML solution and provided an efficient strategy for the fabrication of OLED devices via solution processes in the future.
KW - hole transport polymer
KW - organic light-emitting diode
KW - orthogonal solvent
KW - solution process
KW - thermally activated delayed fluorescence
UR - http://www.scopus.com/inward/record.url?scp=85135768239&partnerID=8YFLogxK
U2 - 10.1021/acsami.2c07659
DO - 10.1021/acsami.2c07659
M3 - Article
C2 - 35894557
AN - SCOPUS:85135768239
SN - 1944-8244
VL - 14
SP - 35969
EP - 35977
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
IS - 31
ER -