Multidentate Molecule Anchoring Halide Perovskite Surface and Regulating Crystallization Kinetics toward Efficient Light-Emitting Diodes.

Functional passivators are conventionally utilized in modifying the crystallization properties of perovskites to minimize the non-radiative recombination losses in perovskite light-emitting diodes (PeLEDs). However, the weak anchor ability of some commonly adopted molecules has limited passivation ability to perovskites and even may desorb from the passivated defects in a short period of time, which bring about plenty of challenges for further development of high-performance PeLEDs. Here, a multidentate molecule, formamidine sulfinic acid (FSA), is introduced as a novel passivator to perovskites. FSA has multifunctional groups (S≐O, C≐N and NH2 ) where the S≐O and C≐N groups enable coordination with the lead ions and the NH2 interacts with the bromide ions, thus providing the most effective chemical passivation for defects and in turn the formation of highly stable perovskite emitters. Moreover, the interaction between the FSA and octahedral [PbBr6 ]4- can inhibit the formation of unfavorable low-n domains to further minimize the inefficient energy transfer inside the perovskite emitters. Therefore, the FSA passivated green-emitting PeLED exhibits a high external quantum efficiency (EQE) of 26.5% with fourfold enhancement in operating lifetime as compared to the control device, consolidating that the multidentate molecule is a promising strategy to effectively and sustainably passivate the perovskites.

Highly Simplified Tandem Organic Light-Emitting Devices Incorporating a Green Phosphorescence Ultrathin Emitter within a Novel Interface Exciplex for High Efficiency.

Herein we report a novel design philosophy of tandem OLEDs incorporating a doping-free green phosphorescent bis[2-(2-pyridinyl-N)phenyl-C](acetylacetonato)iridium(III) (Ir(ppy)2(acac)) as an ultrathin emissive layer (UEML) into a novel interface-exciplex-forming structure of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 1,3,5-tri(p-pyrid-3-yl-phenyl)benzene (TmPyPB). Particularly, relatively low working voltage and remarkable efficiency are achieved and the designed tandem OLEDs exhibit a peak current efficiency of 135.74 cd/A (EQE = 36.85%) which is two times higher than 66.2 cd/A (EQE = 17.97%) of the device with a single emitter unit. This might be one of the highest efficiencies of OLEDs applying ultrathin emitters without light extraction. Moreover, with the proposed structure, the color gamut of the displays can be effectively increased from 76% to 82% NTSC if the same red and blue emissions as those in the NTSC are applied. A novel form of harmonious fusion among interface exciplex, UEML, and tandem structure is successfully realized, which sheds light on further development of ideal OLED structure with high efficiency, simplified fabrication, low power consumption, low cost, and improved color gamut, simultaneously.

Interleukin-10 may participate in regulating trophoblast invasion in human placentae throughout gestation.

PROBLEM: A successful human pregnancy requires cytotrophoblasts from the fetal portion of the placenta to adopt tumor-like properties. But unlike tumor metastasis, cytotrophoblast invasion is highly regulated both spatially and temporally. The mechanisms that regulate human trophoblast invasion are understood poorly. METHOD OF STUDY: With a view to obtain some findings on the mechanisms that regulate human trophoblast invasion, we applied the semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) method to compare the expression of invasion-associated genes in cytotrophoblasts isolated from first- and third-trimester placental tissues. RESULTS: In trophoblast cells of first-trimester pregnancy, the mRNA contents of matrix metalloproteinase (MMP)-9 and urokinase-type plasminogen activator (uPA) were higher than that in the third-trimester cytotrophoblasts, while no difference of MMP-2 mRNA expression level was found between trophoblastic cells of different gestational ages. The expression level of plasminogen activator inhibitors-1 mRNA in first-trimester cytotrophoblasts was shown to be much lower than that in trophoblast cells prepared from third-trimester placental tissues. Furthermore, expression of both tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in cytotrophoblasts were significantly up-regulated in third-trimester when compared with the first-trimester of pregnancy. To further investigate the factors that caused the change of invasion-associated genes expression in trophoblast cells, we found that interleukin-10 (IL-10) could decrease the content of MMP-9 mRNA in cytotrophoblasts of first-trimester gestation, and the magnitude of suppression increased with increasing IL-10 concentration. CONCLUSION: The gradually reduced trophoblast invasion with gestational weeks might be on account of the change of proteolytic enzymes/activator/inhibitor genes expression. IL-10 could be one of the factors participating in the regulation of trophoblast invasion during gestational process.