Light-emitting diodes based on all-inorganic copper halide perovskite with self-trapped excitons

Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel copper-based all inorganic perovskite CsCu2I3 with much enhanced stability has been reported with a potential photoluminescence quantum yield(PLQY)over 20%and self-trapped excitons(STE).By taking advantage of its extraordinary thermal stability,we successfully fabricate high-quality CsCu2I3 film through direct vacuum-based deposition(VBD)of CsCu2I3 powder.The resulting film shows almost the same PLQY with the synthesized powder,as well as excellent uniformity and stability.The perovskite light-emitting diodes(Pe-LED)based on the evaporated CsCu2I3 emitting layer achieve a luminescence of 10 cd/m2 and an external quantum efficiency(EQE)of 0.02%.To the best of our knowledge,this is the first CsCu2I3 Pe-LED fabricated by VBD with STE property,which offers a new avenue for lead-free Pe-LED.

Effects of Jasmonic Acid on the Expression of Capsaicin Biosynthesis Related Genes in Chili Pepper(Capsicum annuum)

To explore the regulatory effects of jasmonic acid （JA） on the expression of the genes involved in capsaicin biosynthesis pathway, the mRNA expression of the genes was determined by fluorescence-based quantitative PCR 0, 4, 12, 24 and 48 h after chili peppers （Capsicum annuum var. conoides） were treated with 100 μmol/L JA, and the content of capsaicin was measured by high performance liquid chromatography （HPLC） 0, 1, 3, 6, 10 and 15 d after JA treatment. The results showed that JA upregulated the mRNA levels of pal, C4h, Comt, 4Cl, Hct, Paint, Bcat, FatA and pun1 in chili pepper, thus promoting the synthesis of capsaicin to different extents.

Bioinformatics and Expression Analysis of CaERF Gene in Capsicum

AP2/ERF transcription factor is a kind of plant-specific transcription factor,which is widely involved in the whole process of plant growth and development,and has important regulatory effects in plant secondary metabolism.In this study,the CaERF gene was cloned from Capsicum annuum by RT-PCR.The bioinformatics and expression analysis revealed that the CDS region of this gene is 795 bp in length,encoding 264 amino acids,and the molecular weight and isoelectric point of the protein are 30.1 KD and 5.74,respectively;the gene encodes a 58-amino acid DNA-binding domain AP2 at 533-706,which is closest to Capsicum chinense in genetics;and the gene is expressed early in the fruit development from 16 to 20 d after flowering,and related to the level of pun 1 gene expression.The cloning and expression analysis of CaERF transcription factor gene laid a foundation for further study on the regulation of capsaicin synthesis.

Analysis of Cloning and Expression Characteristics of Capsicum chinense Jacq. CcMYB Gene

In order to discuss the role of MYB gene in capsaicine synthesis process, one CcMYB gene was cloned from Capsicum chinense Jacq. by RT-PCR. Its cDNA has a total length of 1 038 bp, and was speculated to code 345 amino acids, comprising an complete open reading frame. The isoelectric point is 8.57, and the molecular weight is 38.2 KD. The protein is a neutral hydrophobin without transmentbrane structure. There are two MYBDNA domains at the N terminal. The fluorescence quantitative PCR results showed that CcMYB gene was expressed in all the root, stem, leaf, flower, placenta and fruit tissue of pepper, and the expression level was the highest in fruit ; and CcMYB was expressed in fruit at the highest level at turning stage, and at the second highest level at expansion stage, which accords with the expression profile of punl gene in fruit development period. It is speculated that CcMYB gene plays an important role in the regulation of capsaicine synthesis in C. chinense fruit.

Solution-Processed Hybrid Europium (Ⅱ) lodide Scintillator for Sensitive X-Ray Detection

Lead halide perovskite nanocrystals have recently demonstrated great potential as x-ray scintillators,yet they stll suffer toxicity issues,inferior light yield(LY)caused by severe self-absorption.Nontoxic bivalent europium ions(Eu^(2+))with intrinsically efficient and self-absorption-free d-f transition are a prospective replacement for the toxic Pb^(2+).Here,we demonstrated solution-processed organic-inorganic hybrid halide BA_(10)Eul_(12)(BA denotes C_(4)H_(9)NH_(4)^(+))single crystals for the first time.

All-vacuum fabrication of yellow perovskite light-emitting diodes

Yellow light-emitting diodes(LEDs) are widely utilized in high-quality lighting, light communication,indicator lamps, etc. Owing to their outstanding material properties and device performance, the metal halide perovskites have demonstrated a significant potential for LED applications. However, the performance of the yellow perovskite LEDs(PeLEDs) is inferior to that of their green and red counterparts, with the maximum external quantum efficiency(EQE) limited to ~3.1%. Further, a majority of the yellow PeLEDs are fabricated using the spin-coating methods. The current study reports the development of the yellow CsPbBr_(2)I PeLEDs based on an all-vacuum deposition approach, which has been widely employed in the commercial organic LEDs(OLEDs). By controlling the co-evaporation rate of CsI and PbBr;, the growth kinetics of the perovskite layer are regulated to achieve a small grain size of~31.8 nm. Consequently, an improved radiative recombination rate(8.04 × 10^(-9)cm^(3)/s) is obtained owing to the spatial confinement effect. The PeLEDs based on the optimal perovskite film demonstrate the yellow electroluminescence(574 nm) with a maximum EQE of ~3.7% and luminance of~16,200 cd/m^(2), thus, representing one of the most efficient and bright yellow PeLEDs. Overall, this study provides a useful guideline for realizing the efficient PeLEDs based on the thermal evaporation strategy and highlights the potential of PeLED as an efficient and bright yellow light source.