A new star-shaped oligoelectrolyte (TEFCOONa) with triphenylamine as the core, acetylene as linkage and anionic fluorenes as arms was obtained and used for direct imaging in living PANC-1 cells. Because of the hydrophobic conjugated groups of the oli-goelectrolyte, TEFCOONa can form nanospheres with an average diameter of^75 nm in 10 mmol/L PBS. These nanospheres possess a relatively high absolute quantum yield (16.5% in PBS), low cytotoxicity and can penetrate into the nucleus through the cytoplasm, which is essential for living cellular imaging. Collectively, these results validate our rational design of conjugated oligoelectrolyte and even hyper branched polymers-copolyelectrolyte as effective nanovectors for bioimaging and other clinical applications.
SONG WenLiJIANG RongCuiYUAN YanLU XiaoMeiHU WenBoFAN QuLiHUANG Wei
Device modeling is constructive in finding the dependency of devices efficiency on structure parameters and material properties. For the sake of looking into the physics mechanism of organic solar cells (OSCs), as well as predicting their maximum attainable efficiency, numerical modeling is widely utilized to simulate the behavior of OSCs. Although some indispensable parameters are neglected or hypothesized because of inexplicitness in simulation models for OSCs, numerical modeling can describe the kinetic process in OSCs intuitively. This paper summarizes the optical/electrical models in the BHJ solar cell, as well as addresses their corresponding development in recent years on the basis of device physics and its working principle. Applications of numerical modeling and comments on modeling results are summarized. Meanwhile, precision and open questions about every model are discussed.
Two bipolar materials,2,5-bis(2-(9H-carbazole-9-yl)phenyl)-1,3,4-oxadiazole(o-CzOXD)and 2,5-bis(2-(3',6'-di-tert-butyl-9H-carbazole-9-yl)phenyl)-1,3,4-oxadiazole(tBu-o-CzOXD),were synthesized according to reported methods.In parallel study,it was demonstrated that introduction of inert tert-butyl group improved material thermal stability,even though this modification only had a slight influence to the photophysical and electrochemical properties of these materials.A comparative study focusing on effects of heat treatment was carried out on the quartz glass substrates with vacuum deposited films containing one of the bipolar host doped with 6 wt%fac-tris(2-phenylpyridinato-N,C2’)iridium(Ir(ppy)3).Results show that when the two samples were heated,the absorption,emission,and photo images of the host:dopant system changed,with the o-CzOXD suffering more severe degradation under high temperature,which is consistent with their thermal stability.In addition,it was proved that the high temperature-annealed host:dopant system can enhance the emission of the dopant.This finding was used as a guideline to improve our device performance.We fabricated two types of phosphorescent organic light-emitting devices(PhOLEDs),one was based on o-CzOXD,the other was based on tBu-o-CzOXD.They had analogous structure.We investigated the effect of heat on device performance by selectively annealing.Although these two freshly prepared devices exhibited similar performance,when annealed at 90°C for 10 min,the OLEDs based on tBu-o-CzOXD showed significant performance enhancement,which can be attributed to the observation that annealing Ir(ppy)3 doped host can change film morphology and enhance the dopant emission.The maximum efficiencies of the freshly prepared tBu-o-CzOXD device were 25.8 cd A-1,23.1lm W-1,and 9.3%;whereas those for annealed device were 47.0 cd A-1,42.2 lm W-1,and 13.4%.
WANG HongJiaoLIU ChenMI BaoXiuSANG JieLI XinGAO ZhiQiang
We develop high efficiency solution-processed pure green organic light-emitting devices using a starburst molecule 7,7′,7″-(5,5,10,10,15,15-hexahexyl-10,15-dihydro-5H-diindeno[1,2-a:1′,2′-c]fluorene-2,7,12-triyl)tris(4-(4-(9H-carbazol-9-yl)phenyl)benzo[c][1,2,5]thiadiazole)(TRcz)doped 2-methyl-9,10-di(2-naphthyl)anthracene(MADN)as the emitting layers.The electroluminescence properties of the devices with different doping concentrations are investigated.With the increasing doping concentration from 0.5wt%to 5wt%,the maximum efficiency changes from 4.8cd/A to 8.4cd/A.Under the optimal concentration of 4wt%,the device shows pure green emission at 516nm with a chromaticity coordinate of(0.30,0.59)as well as a high brightness of 19900cd/m^(2)and a high efficiency of 10.1cd/A,which are better than 11490cd/m^(2)and 4.2cd/A obtained in the undoped device.
