Frontiers of Optoelectronics, 2018, 11 (4): 375–384, 网络出版: 2019-01-10
Efficient deep red phosphorescent OLEDs using 1,2,4-thiadiazole core-based novel bipolar host with low efficiency roll-off
Efficient deep red phosphorescent OLEDs using 1,2,4-thiadiazole core-based novel bipolar host with low efficiency roll-off
1, 2, 4-thiadiazole core, low efficiency rolloff deep red phosphorescent devices symmetrical chargetrapping effect
摘要
Abstract
A series of 1,2,4-thiadiazole core-based bipolar materials, 2,2'-(1,2,4-thiadiazole-3,5-diyl)bis(N,Ndiphenylaniline) (o-TPATHZ), 3,3′-(1,2,4-thiadiazole-3,5- diyl)bis(N,N-diphenylaniline) (m-TPATHZ) and 4,4'-(1,2,4-thiadiazole-3,5-diyl)bis(N,N-diphenylaniline) (p-TPATHZ) were developed as the host matrixes for the deep red phosphorescent emitters tris(1-phenylisoqiunoline) iridium (Ir(piq)3) and [bis(2-methyldibenzo-[f,h]-quinoxaline) Ir(III)(acetylacetonate)] (Ir(MDQ)2(acac)). By systematic studying, we demonstrated that there are two types of charge-trapping effect within the emissive layers through adjusting the host-guest compatibility. And, it is revealed that a symmetric charge-trapping effect can contribute to realizing a stable charge-balance, which led to a mitigating efficiency roll-off at high current density. Consequently, a maximum external quantum efficiency (EQE) of 16.2% was achieved by an optimized device with p-TPATHZ-Ir(piq)3 emissive layer. Remarkably, the EQE still remained as high as 15.7% at the high luminance of 1000 cd/m2.
, , , , . Efficient deep red phosphorescent OLEDs using 1,2,4-thiadiazole core-based novel bipolar host with low efficiency roll-off[J]. Frontiers of Optoelectronics, 2018, 11(4): 375–384. Runda GUO, Wenzhi ZHANG, Qing ZHANG, Xialei LV, Lei WANG. Efficient deep red phosphorescent OLEDs using 1,2,4-thiadiazole core-based novel bipolar host with low efficiency roll-off[J]. Frontiers of Optoelectronics, 2018, 11(4): 375–384.
PDF全文
