Defect Passivation in Quasi-2D Perovskite Light-Emitting Diodes by an Ibuprofen Additive.

It is well known that the inferior film morphology and the excessive surface/interface defect states are two obstacles to achieving high electroluminescence performance of quasi-2D perovskite light-emitting diodes (PeLEDs). To solve these problems, ibuprofen was introduced as an additive in the quasi-2D perovskite emitting layer. More efficient photoluminescence is demonstrated. Further, optimized quasi-2D PeLEDs with a current efficiency of 55.93 cd/A are confirmed and 5.7-fold enhancement in device stability is obtained. The physical mechanism of the remarkable improvement is investigated by kinds of measurements. Three aspects should be counted into it. First, the introduction of ibuprofen can passivate defects, thus making the quasi-2D perovskite emitting layer more dense and homogeneous. The reason should be that the C═O functional group and C═C bond in the benzene ring in ibuprofen can coordinate the unsaturated Pb2+ perovskite emitting layer. Meanwhile, the related exciton harvesting process is investigated. The proportion of the crystalline phases (small n and large n phase) can be tuned to benefit the energy funneling process. Finally, the analysis of the current density and voltage curves of the hole-dominated devices and the electron-dominated devices is conducted by utilizing the space charge-limited current (SCLC) methods.

A Hybrid Functional Study on Perovskite-Based Compounds CsPb1-αZnαI3-ßXß (X = Cl or Br).

Inorganic perovskites have attracted a great deal of attention because of their stability. Unfortunately, a weak optical response and the toxicity of lead are hampering their development. Motivated by these facts, we focus herein on the perovskite-based doped series CsPb1-αZnαI3-ßXß (X = Cl or Br). The geometric structures and the electronic and optical properties of CsPb1-αZnαI3-ßXß (X = Cl or Br) are investigated systematically by hybrid functional theory. Analysis of the electronic properties indicates that Zn/Cl/Br mono-doping and co-doping efficiently tune bandgaps. Moreover, we find that the ability to obtain electrons for CsPb0.625Zn0.375I2Cl is superior to the abilities of the others, which implies a stronger electron transition. In addition, CsPb0.625Zn0.375I2Cl and CsPb0.625Zn0.375I2Br show stronger visible-light responses in the range of 467-780 nm. Both CsPb0.625Zn0.375I2Cl and CsPb0.625Zn0.375I2Br are hence good choices for photovoltaic applications. Furthermore, the physically accessible region is also explored herein. These findings shed new light on the design of highly efficient and low-lead perovskite-based optoelectronic materials.

Improving antitumor outcomes for palliative intratumoral injection therapy through lecithin- chitosan nanoparticles loading paclitaxel- cholesterol complex.

BACKGROUND: Intratumoral injection is a palliative treatment that aims at further improvement in the survival and quality of life of patients with advanced or recurrent carcinomas, or cancer patients with severe comorbidities or those with a poor performance status. METHODS: In this study, a solvent-injection method was used to prepare paclitaxel-cholesterol complex-loaded lecithin-chitosan nanoparticles (PTX-CH-loaded LCS_NPs) for intratumoral injection therapy, and the physicochemical properties of NPs were well characterized. RESULTS: The particle size and zeta potential of PTX-CH-loaded LCS_NPs were 142.83±0.25 nm and 13.50±0.20 mV, respectively. Release behavior of PTX from PTX-CH-loaded LCS_NPs showed a pH-sensitive pattern. The result of cell uptake assay showed that PTX-CH-loaded LCS_NPs could effectively enter cells via the energy-dependent caveolae-mediated endocytosis and macropinocytosis in company with the Golgi apparatus. Meanwhile, PTX-CH-loaded LCS_NPs had a better ability to induce cell apoptosis than PTX solution. The in vivo antitumor results suggested that PTX-CH-loaded LCS_NPs effectively inhibited mouse mammary cancer growth and metastasis to distant organs and significantly improved the survival rate of tumor-bearing mice by intratumoral administration. CONCLUSION: In general, our study demonstrated that PTX-CH-loaded LCS_NPs used for palliative treatment by intratumoral injection showed improved safety and antitumor efficacy, which provided an alternative approach in the field of palliative chemotherapy.

84% efficiency improvement in all-inorganic perovskite light-emitting diodes assisted by a phosphorescent material.

A novel mixed perovskite emitter layer is applied to design all-inorganic cesium lead halide perovskite light-emitting diodes (PeLEDs) with high electroluminescence (EL) performance, by combining CsPbBr3 with iridium(iii)bis[2-(4',6'-difluorophenyl)pyridinato-N,C2']-picolinate (FIrpic), where FIrpic is a phosphorescent material with very high internal quantum efficiency (IQE) approaching 100%. The CsPbBr3:FIrpic PeLEDs show a maximum luminance of 5486 cd m-2, and an external quantum efficiency of 0.47%, which are 1.84 and 1.76 times that of neat CsPbBr3 PeLEDs, respectively. It is found that FIrpic molecules as an assistant dopant can efficiently transmit energy from the excitons of FIrpic to the excited state of the CsPbBr3 emitter via a Förster energy transfer process, leading to enhanced EL efficiency in the CsPbBr3:FIrpic PeLEDs.

Transfer-free synthesis of doped and patterned graphene films.

High-quality and wafer-scale graphene on insulating gate dielectrics is a prerequisite for graphene electronic applications. For such applications, graphene is typically synthesized and then transferred to a desirable substrate for subsequent device processing. Direct production of graphene on substrates without transfer is highly desirable for simplified device processing. However, graphene synthesis directly on substrates suitable for device applications, though highly demanded, remains unattainable and challenging. Here, we report a simple, transfer-free method capable of synthesizing graphene directly on dielectric substrates at temperatures as low as 600 °C using polycyclic aromatic hydrocarbons as the carbon source. Significantly, N-doping and patterning of graphene can be readily and concurrently achieved by this growth method. Remarkably, the graphene films directly grown on glass attained a small sheet resistance of 550 Ω/sq and a high transmittance of 91.2%. Organic light-emitting diodes (OLEDs) fabricated on N-doped graphene on glass achieved a current density of 4.0 mA/cm(2) at 8 V compared to 2.6 mA/cm(2) for OLEDs similarly fabricated on indium tin oxide (ITO)-coated glass, demonstrating that the graphene thus prepared may have potential to serve as a transparent electrode to replace ITO.

Control of conjugation degree via position engineering to highly efficient phosphorescent host materials.

The C3 meta-position of fluorene is utilized to construct high-triplet energy compounds. Incorporating a spiroacridine structure, two new host materials SAFDPA and SAFCz were facilely obtained. Their thermal and photophysical properties are fully investigated. The best efficiencies of 19.4%/21.5% of blue/white devices are achieved by SAFCz.

[Three-column plate internal fixation for the treatment of complex tibial plateau fracture through antero-midline and postero-medial approaches].

OBJECTIVE: To study technique and clinical therapeutic effects of internal fixation with three-column plates for the treatment of complex tibial plateau fractures through antero-midline and postero-medial approaches. METHODS: From January 2010 to December 2012, 28 patients with complex tibial plateau fractures were treated with internal fixation using three-column plates through antero-midline and postero-medial approaches. There were 17 males and 11 females, with an average age of 45.3 years old (ranged, 28 to 64 years old). Twelve patients had injuries in the left side and 16 patients had injuries in the right side. According to Schatzker classification, 12 patients were type V, 16 patients were type VI. According to three-column classification, all the patients had injuries of lateral, medial and posterior columns. The mean interval from injury to operation was 9.4 days (ranged, 6 to 15 days). The main clinical symptoms were knee joint swelling, deformity and limitation of motion before operation. The X-ray and CT showed all patients had complex tibial plateau fractures, which involved in the lateral, medial and posterior columns. The therapeutic effects were evaluated by fracture healing time, hospital for special surgery knee score (HSS) at one year after operation. The indexes such as tibial plateau-tibial shaft angle (TPA), posterior slope angle (PA) and femoral-tibial angle (FfA) were compared between immediate postoperation and one year after operation. RESULTS: All incisions primarily healed without postoperative complications such as infection and cutaneous necrosis. All the patients were followed up, and the duration ranged from 12 to 24 months, with a mean of 18.1 months. The bone union time ranged from 5 to 10 months (mean, 7.8 months) after operation. Knee joint swelling and pain disappeared after bony union, and joint function completely recovered. The results of hospital for special surgery knee score (HSS) was 27.81 ± 2.17 in pain, 19.52 ± 2.05 in function,15.82 ± 1.73 in passive range of motion, 8.51 ± 1.32 in muscle strength, 8.33 ± 1.08 in flexion deformity, 9.36 ± 0.52 in joint stability, and the total mean score was 89.35 ± 3.19. According to results of HSS, 20 patients got an excellent result, 5 good,2 fair and 1 poor. There were no significant differences in tibial plateau-tibial shaft angle (TPA), posterior slope angle (PA) and femoral-tibial angle (FTA) between immediate postoperation and one year after operation. CONCLUSION: Three-column plate internal fixation for the treatment of complex tibial plateau fractures through antero-midline and posteromedial approaches is effective to achieve anatomic reduction,rigid internal fixation and early functional exercise.

Silicon-based material with spiro-annulated fluorene/triphenylamine as host and exciton-blocking layer for blue electrophosphorescent devices.

A novel silicon-based compound, 10-phenyl-2'-(triphenylsilyl)-10H-spiro[acridine-9,9'-fluorene] (SSTF), with spiro structure has been designed, synthesized, and characterized. Its thermal, electronic absorption, and photoluminescence properties were studied. Its energy levels make it suitable as a host material or exciton-blocking material in blue phosphorescent organic light-emitting diodes (PhOLEDs). Accordingly, blue-emitting devices with iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,C(2)']picolinate (FIrpic) as phosphorescent dopant have been fabricated and show high efficiency with low roll-off. In particular, 44.0 cd A(-1) (41.3 lm W(-1)) at 100 cd m(-2) and 41.9 cd A(-1) (32.9 lm W(-1)) at 1000 cd m(-2) were achieved when SSTF was used as host material; 28.1 lm W(-1) at 100 cd m(-2) and 20.6 lm W(-1) at 1000 cd m(-2) were achieved when SSTF was used as exciton-blocking layer. All of the results are superior to those of the reference devices and show the potential applicability and versatility of SSTF in blue PhOLEDs.

Enhanced hole injection in phosphorescent organic light-emitting diodes by thermally evaporating a thin indium trichloride layer.

An ultrathin layer of indium trichloride (InCl(3)) is thermally evaporated on the indium tin oxide (ITO) anode to enhance the hole injection in simplified phosphorescent organic light-emitting diodes (PHOLEDs). Comparing with the device with ultraviolet (UV)-ozone treatment, the device modified by InCl(3) exhibits a maximum current efficiency of 82.2 cd/A measured at about 2000 cd/cm(2) and 36% improvement in power efficiency measured at 20 mA/cm(2). More importantly, more than three times improvement in half lifetime estimated at an initial luminance of 1000 cd/cm(2) is achieved. The investigations using ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and the bias- and temperature-dependent current density-voltage characteristics in the related hole-dominated devices have revealed that the improved device performance is mainly attributed to the enhanced hole injection resulting from the lowered hole injection barrier height in the InCl(3)-modified devices.

New dibenzofuran/spirobifluorene hybrids as thermally stable host materials for efficient phosphorescent organic light-emitting diodes with low efficiency roll-off.

A new class of host materials DBFSF (DBFSF2 and DBFSF4) is facilely synthesized through a Suzuki coupling reaction between dibenzofuran and spirobifluorene. Their thermal, electrochemical, electronic absorption and photoluminescent properties are fully investigated. High glass transition temperatures (T(g)) of 115 °C and 124 °C are observed for DBFSF2 and DBFSF4, respectively, due to the introduction of bulky spirobifluorene groups. As expected, the DBFSF4 with a twisted-linkage exhibits higher triplet energy than DBFSF2 and can be used in blue and green phosphorescent OLEDs. Electrophosphorescent devices with DBFSF2 and DBFSF4 as hosts were fabricated. Besides the good current efficiencies of 22.2 cd A(-1) for blue and 64.4 cd A(-1) for green, low efficiency roll-off has also been achieved for both devices.