Influence of Substituted Pyridine Rings on Physical Properties and Electron Mobilities of 2-Methylpyrimidine Skeleton-Based Electron Transporters

High‐Performance Green OLEDs Using Thermally Activated Delayed Fluorescence with a Power Efficiency of over 100 lm W−1

“…The electron mobility ( µ e) was 10 −5 cm 2 V −1 s −1 for TPBi, 10 −4 cm 2 V −1 s −1 for B3PyPB, and 10 −6 cm 2 V −1 s −1 for B4PyPPM. [ 24,25 ] The device structure was [ITO (130 nm)/TAPC (35 nm)/5 wt% 4CzIPN-doped CBP (15 nm)/ETL (65 nm)/LiF (0.8 nm)/Al (100 nm)]. Table S-2 in the Supporting Information summarizes all the device performances.…”

Optimizing the Charge Balance of Fluorescent Organic Light‐Emitting Devices to Achieve High External Quantum Efficiency Beyond the Conventional Upper Limit

“…We used fi ve types of electron-transporting materials (ETMs) for the ETL: tris(8-quinolinolato)aluminum (Alq 3 ), 1,4-di(1,10-phenanthrolin-3-yl)benzene (DPB), bis-1,2-(3,5-di-3-pyridylphenyl) benzene (B3PyPB), [ 11 ] bis-4,6-(3,5-di-3-pyridyl-phenyl)-2-methylpyrimidine (B3PyMPm), [ 12 , 13 ] and bis-4,6-(3,5-di-4-pyridyl-phenyl)-2-methylpyrimidine (B4PyMPm). [ 13 ] Two hole-transporting materials (HTMs), N , N ′ -di(naphthalene-1-yl)-N , N ′ -diphenylbenzidine (NPD) and 1,1-bis-(4-bis(4-tolyl)-aminophenyl)cyclohexene (TAPC), were used in the HTL. The ETMs are particularly important because their lowest unoccupied molecular orbital (LUMO) levels are generally not estimated from direct measurements, except inversephotoemission spectroscopy (IPES) measurements, and these values are still ambiguous.…”

“…When we used non-Alq 3 compounds for the ETL, the EQEs of the devices B, C, D, and E became much higher than that of device A with an Alq 3 ETL ( Figure 2 ) because of the much higher electron mobilities of DBP, B3PyMPm (1.5 × 10 − 5 cm 2 V − 1 s − 1 ), B4PyMPm (1.0 × 10 − 4 cm 2 V − 1 s − 1 ), and B3PyPB (1.0 × 10 − 4 cm 2 V − 1 s − 1 ). [11][12][13] Among them, the device E with B3PyPB showed the highest effi ciency of over 6%. After the optimization of the ETLs, we used TAPC for the HTL instead of NPD.…”

Recent progress of pyrimidine derivatives for high-performance organic light-emitting devices

“…Moreover, bis-4,6-(3,5-dipyridylphenyl)-2-methylpyrimidine (BPyMPM) derivatives exhibit different optoelectronic properties, such as ionization potential, electron affinity, and electron mobility depending on the nitrogen position on the peripheral pyridine rings. 53,54 Interestingly, a 100-fold increase of the electron mobility has been observed based on the nitrogen position of pyridine rings. These series of pyrimidine-based ETMs are also beneficial for exciplex-based high-performance OLEDs, as shown in the next section.…”