A series of novel hyperbranched polymers （HBPs） consisting ofa 2,7-subsituted 9-（heptadecan-9-yl）-9H-carbazole unit （A2＋A2＇） and a tetra-substituted green thermally activated delayed fluorescence （TADF） dye ...A series of novel hyperbranched polymers （HBPs） consisting ofa 2,7-subsituted 9-（heptadecan-9-yl）-9H-carbazole unit （A2＋A2＇） and a tetra-substituted green thermally activated delayed fluorescence （TADF） dye of 2,3,5,6-tetra（9H- carbazol-9-yl）-4-pyridinecarbonitrile （4CzCNPy, B4） have been synthesized via Suzuki cross-coupling reaction following an ＂Az＋A2＇＋B4＂ method. The polymers are named according to the polymerization ratio of 4CzCNPy monomer （5 mol%, 10 mol% and 15 mol% for HBPs of P2-P4 respectively, and 0 mol% for the control linear polymer P1）. Their thermal, optoelectronic and electrochemical properties have been characterized by a combination of techniques. All the polymers exhibit high thermal stability with the decomposition temperatures （Ta） above 400 ℃ and glass transition temperatures （Tg） up to 98℃. Unfortunately, the incorporation of TADF moiety into these HBP materials induced non-TADF characteristics. However, when the HBPs functionalized as the host for our previously developed 4CzCNPy TADF dopant in solution processed devices, maximum external quantum efficiency of 5.7% and current efficiency of 17.9 cd/A have been achieved in P3-based device, which is significantly higher than those of 1.5% and 4.2 cd/A for the linear polymer P1.展开更多
In this study, an InGaN lighting-emitting diode （LED） containing GaN/A1GaN/GaN triangular barriers is proposed and investigated numerically. The simulation results of output performance, carrier concentration, and r...In this study, an InGaN lighting-emitting diode （LED） containing GaN/A1GaN/GaN triangular barriers is proposed and investigated numerically. The simulation results of output performance, carrier concentration, and radiative recombination rate indicate that the proposed LED has a higher output power and an internal quantum efficiency, and a lower efficiency droop than the LED containing conventional GaN or A1GaN barriers. These improvements mainly arise from the modified energy bands, which is evidenced by analyzing the LED energy band diagram and electrostatic field near the active region. The modified energy bands effectively improve carrier injection and confinement, which significantly reduces electron leakage and increases the rate of radiative recombination in the quantum wells.展开更多
We report Al/MoO3 thin film used as a complex anode in high-performance OLEDs. The unique efficacy of the device was found to result from the enhanced injection of holes into the commonly used hole-transporting molecu...We report Al/MoO3 thin film used as a complex anode in high-performance OLEDs. The unique efficacy of the device was found to result from the enhanced injection of holes into the commonly used hole-transporting molecules due to a large reduction in the interface dipole at the anode/organic interface. The superior optical charac-teristics are attributed to a strong cavity effect, Due to the ease of processing Al/MoO3 we successfully demonstrated large-area flexible OLEDs on plastic substrates with uniform emission.展开更多
基金financially supported by the National Natural Science Foundation of China(No.21304047)Natural Science Foundation of Jiangsu Province(No.BK2016042)Research Fund for the Doctoral Program of Higher Education(No.20133221120015)
文摘A series of novel hyperbranched polymers （HBPs） consisting ofa 2,7-subsituted 9-（heptadecan-9-yl）-9H-carbazole unit （A2＋A2＇） and a tetra-substituted green thermally activated delayed fluorescence （TADF） dye of 2,3,5,6-tetra（9H- carbazol-9-yl）-4-pyridinecarbonitrile （4CzCNPy, B4） have been synthesized via Suzuki cross-coupling reaction following an ＂Az＋A2＇＋B4＂ method. The polymers are named according to the polymerization ratio of 4CzCNPy monomer （5 mol%, 10 mol% and 15 mol% for HBPs of P2-P4 respectively, and 0 mol% for the control linear polymer P1）. Their thermal, optoelectronic and electrochemical properties have been characterized by a combination of techniques. All the polymers exhibit high thermal stability with the decomposition temperatures （Ta） above 400 ℃ and glass transition temperatures （Tg） up to 98℃. Unfortunately, the incorporation of TADF moiety into these HBP materials induced non-TADF characteristics. However, when the HBPs functionalized as the host for our previously developed 4CzCNPy TADF dopant in solution processed devices, maximum external quantum efficiency of 5.7% and current efficiency of 17.9 cd/A have been achieved in P3-based device, which is significantly higher than those of 1.5% and 4.2 cd/A for the linear polymer P1.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFB0403100 and 2017YFB0403101)the National Natural Science Foundation of China(Grant Nos.61404114,61504119,and 11004170)+1 种基金the China Postdoctoral Science Foundation(Grant No.2017M611923)the Jiangsu Planned Projects for Postdoctoral Research Funds,China(Grant No.1701067B)
文摘In this study, an InGaN lighting-emitting diode （LED） containing GaN/A1GaN/GaN triangular barriers is proposed and investigated numerically. The simulation results of output performance, carrier concentration, and radiative recombination rate indicate that the proposed LED has a higher output power and an internal quantum efficiency, and a lower efficiency droop than the LED containing conventional GaN or A1GaN barriers. These improvements mainly arise from the modified energy bands, which is evidenced by analyzing the LED energy band diagram and electrostatic field near the active region. The modified energy bands effectively improve carrier injection and confinement, which significantly reduces electron leakage and increases the rate of radiative recombination in the quantum wells.
基金Prject supported by the National Natural Science Foundation of China(No.61076066)the Doctor Foundation of Shaanxi University of Science and Technology,China(No.BJ09-07)
文摘We report Al/MoO3 thin film used as a complex anode in high-performance OLEDs. The unique efficacy of the device was found to result from the enhanced injection of holes into the commonly used hole-transporting molecules due to a large reduction in the interface dipole at the anode/organic interface. The superior optical charac-teristics are attributed to a strong cavity effect, Due to the ease of processing Al/MoO3 we successfully demonstrated large-area flexible OLEDs on plastic substrates with uniform emission.
