The photoluminescence quantum yield (PLQY) of blue-violet emission of CsPbCl quantum dots (QDs) is still low, which has limited their application in multi-colour displays. It is important to search for efficient perovskite phosphors within this wavelength range. In this work, we first considerably enhanced the photoluminescence quantum yield (PLQY) of the CsPbCl QDs from 3.2 to 10.3% by the introduction of potassium ions (K). Then, various lanthanide elements (La, Y, Eu, Lu) were further doped into KCsPbCl QDs. The lanthanide doped KCsPbCl QDs still demonstrated emissions around 408 nm and the PLQY was further improved to 31%. Finally, we carried out anion exchange by gradually substituting chlorine with bromine. Efficient and tunable emissions ranging from 408-495 nm were obtained, with a maximum PLQY of 90%. This work provides a new approach to improve the efficiency of the blue-violet light of perovskite QDs.
Oxidative DNA damage plays crucial roles in the pathogenesis of numerous diseases including cancer. 8-hydroxy-2′-deoxyguanosine (8-OHdG) is the most representative product of oxidative modifications of DNA, and urinary 8-OHdG is potentially the best non-invasive biomarker of oxidative damage to DNA. Herein, we developed a sensitive, specific and accurate method for quantification of 8-OHdG in human urine. The urine samples were pretreated using off-line solid-phase extraction (SPE), followed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. By the use of acetic acid as an additive to the mobile phase, we improved the UPLC-MS/MS detection of 8-OHdG by 2.7−5.3 times. Using the developed strategy, we measured the contents of 8-OHdG in urine samples from 142 healthy volunteers and 84 patients with colorectal cancer (CRC). We observed increased levels of urinary 8-OHdG in patients with CRC and patients with tumor metastasis, compared to healthy controls and patients without tumor metastasis, respectively. Additionally, logistic regression analysis and receiver operator characteristic (ROC) curve analysis were performed. Our findings implicate that oxidative stress plays important roles in the development of CRC and the marked increase of urinary 8-OHdG may serve as a potential liquid biomarker for the risk estimation, early warning and detection of CRC.
Understanding the oxidation of silicon has been critical to the success of all types of silicon materials, which are the cornerstones of modern silicon technologies. For the recent experimentally obtained two-dimensional silicene, oxidation should also be addressed to enable the development of silicene-based devices. Here we focus on silicene oxides (SOs) that result from the partial or full oxidation of silicene in the framework of density functional theory. It is found that the formation of SOs greatly depends on oxidation conditions, which concern the oxidizing agents of oxygen and hydroxyl. The honeycomb lattice of silicene may be preserved, distorted or destroyed after oxidation. The charge state of Si in partially oxidized silicene ranges from +1 to +3, while that in fully oxidized silicene is +4. Metals, semimetals, semiconductors and insulators can all be found among the SOs, which show a wide spectrum of electronic structures. Our work indicates that the oxidation of silicene should be exquisitely controlled to obtain specific SOs with desired electronic properties.
All-inorganic and low-cost quantum-dot light-emitting diodes (QLEDs) are always desired considering the easy processing and outstanding physical and chemical stability of inorganic oxides. Herein, efficient all-inorganic QLEDs are demonstrated by using NiO and ZnO as the charge transport layers fabricated via ultrasonic spray processes. Excellent device performance is achieved thanks to the introduction of an Al2O3 interlayer between quantum dots (QDs) and an amorphous NiO layer. Transient photoluminescence and electricity measurements indicate that the Al2O3 layer can suppress the exciton quenching induced by the NiO layer and reduce the electron leakage from QDs to NiO. In consequence, relative to that of a device without an Al2O3 layer, the efficiency of an Al2O3-containing device is enhanced by a factor of 539%, increasing from 3.8 cd/A to 20.5 cd/A, and it exhibits color-saturated green emission (peak at 530 nm) and high luminescence (>20 000 cd/m2). These are the best performances for all-inorganic QLEDs reported to date. Meanwhile, it is demonstrated that ultrasonic spray is a feasible and cost-effective technology to construct efficient all-inorganic QLEDs. We anticipate that these results will spur the progress toward realization of high performance and mass production of all-inorganic QLEDs as a platform for QD-based full-color displays.
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