The Y-type compound 67dTPA-FQ combining 2-Phenylfuro[2,3-b]quinoxaline (FQ) with triphenylamine (TPA) has been demonstrated to be a green fluorescence emitter with a 0.40 eV ΔES1T1. Herein, TPA units in 67dTPA-FQ were replaced with 4,4'-dimethoxytriphenylamine (MeOTPA) units to shift S1 energy to lower direction so as to reduce ΔES1T1 and realize thermally activated delayed fluorescence (TADF). Thus, a Y- (67dMeOTPA-FQ) and a T-type (58dMeOTPA-FQ) compounds were synthesized, respectively. As the donor changed from TPA to MeOTPA, the emission of the Y- and T-type compound in toluene shifts to 563 nm and 611nm, and their respective ΔES1T1 reduced to 0.27 eV and 0.07 eV. The delayed time of 1.22 us and 1.56 us for Y- and T-type compounds was achieved. Due to smaller ΔES1T1 and larger spin-orbital coupling of T-type compound, its kRISC (1.52 × 106 s-1) is ~1.5 times that of the Y-type compound (1.00 × 106 s-1), and higher photoluminescence quantum yield was observed in T-type compound (79.1%). The hyperfine coupling involved in T2 state are suggested to be responsible for the TADF feature due to the fact that the S1 and T1 state are charge-transfer character while their T2 state is local excitation character. By combining TADF mechanism of both compounds and TTA processes of 2-Methyl-9,10-bis(naphthalen-2-yl)anthracene (MADN) host, the multi-channeled strategy of triplet exciton utilization is proposed to inhabit the notorious efficiency roll-off observed in TADF-based organic light-emitting device. As expected, the device using MADN as host for 67dMeOTPA-FQ, the maximum brightness is up to 104215 cd m-2, and the external quantum efficiency keep in the 8.23~8.03% with the brightness changed from 55.0 cd m-2 to 90000 cd m-2, only 2.4% efficiency roll-off.
An efficient n-type dopant, sodium borohydride (NaBH4), in tris(8-hydroxyquinoline) aluminium (Alq3) thin film has been developed. Doping NaBH4 in Alq3 can significantly enhance the electron injection and transport, which can reduce the applied voltage and improve the efficiency of organic light-emitting diodes compared with the referenced device. Using the quartz crystal microbalance test, we demonstrated that NaBH4 decomposes following gas formation during the thermal evaporation process. By calculating the deposited fraction of NaBH4, we concluded that boron and metallic sodium were the main components of the dopant, while gaseous hydrogen formed during the evaporation process. We thus found that, among these two components, metallic sodium is most likely to be the active component of the dopant because of its strong electron donor characteristic.
Herein, three self‐assembling materials (SAMs), (pyridine‐4‐ylmethyl)phosphonic acid (PyPA), benzylphosphonic acid (BnPA), and pentafluorobenzyl phosphonic acid (F5BnPA), are selected as hole‐injecting layers in organic light‐emitting diodes (OLEDs) and the effects of the aromatic ring of SAMs on indium tin oxide (ITO) work function (WF), hole injection, and device performances are investigated. After assembling them on ITO, the X‐ray photoemission spectroscopy data suggest that three samples have a similar binding mode, and the ultraviolet photoemission spectroscopy shows the effective change of ITO WF gradually enlarged along the order of PyPA, BnPA, and F5BnPA, resulting in increase in hole‐injecting capability in turn. The calculated molecule dipole of pyridine is 2.65 Debye, clearly larger than that of phenyl (0.32 Debye) and pentafluorophenyl (1.88 Debye), but PyPA presents minimum ITO WF change. Such differentiated WF changes are not only contributed by the molecular dipole of aromatic ring but also their titling angles. In OLEDs based on tris(8‐hydroxyquinoline) aluminum (III) (Alq 3 ), the device modified by PyPA affords the highest external quantum efficiency (EQE) of 1.45% and current efficiency (CE) of 4.62 cd A −1 . However, in the device using 9‐[4‐(4,6‐diphenyl‐1,3,5‐triazine‐2‐yll)phenyl]‐ N,N,N′,N ′‐tetraphenyl‐9H‐carbazole‐3,6‐diamine as emitters, the OLEDs modified by F5BnPA show the best EQE of 24.85% and CE of 81.88 cd A −1 .
Vehicles equipped with automated driving capabilities have shown the potential to improve safety and operations. Advanced driver assistance systems (ADAS) and automated driving systems (ADS) have been widely developed to support vehicular automation. Although the studies on the injury severity outcomes that involve automated driving systems are ongoing, there is limited research investigating the difference between injury severity outcomes of the ADAS and ADS vehicles using real-world crash data. To ensure comprehensive analysis, a multi-source dataset that includes the NHTSA crash database (752 cases), CA DMV crash reports (498 cases), and news outlet data (30 cases) is used. Two random parameters multinomial logit models with heterogeneity in the means and variances are estimated to gain a better understanding of the variables impacting the crash injury severity outcome for the ADAS (SAE Level 2) and ADS (SAE Levels 3-5) vehicles. We found that while 56 percent of crashes involving ADAS vehicles took place on a highway, 84 percent of crashes involving ADS took place in more urban settings. The model estimation results indicate that the weather indicators, traffic incident or work zone indicator, differences in the system sophistication that are captured by both manufacture year and high or low mileage, type of collision, as well as rear and front impact indicators all play a significant role in the crash injury severity. The results offer an exploratory assessment of the safety performance of the ADAS and ADS equipped vehicles in the real-world environment and can be used by the manufacturers and other stakeholder to dictate the direction of their deployment and usage.
A high, density packaged 4-channel optical transceiver using a 1310 nm FP-LD array and a PD array has been newly developed for OC-3, OC-12, Gig-E and fiber channel intermediate reach applications. The output optical power of each of the four LDs is independently controlled by automatic power control (APC). Both module package size and power consumption can be reduced by less than half when compared to the use of four conventional single-channel small form factor pluggable (SFP) modules
We have demonstrated that the T 1 -state energy of a fluorescence dopant (FD) is close to that of the thermally activated delayed fluorescence (TADF)-type exciplex co-host, and the energy loss caused by the T 1 states of the FD could be suppressed in TADF-sensitized fluorescence (TSF) OLEDs.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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