Approaches to enhance electroluminescent efficiency of light-emitting diodes based on quasi-two-dimensional perovskite

Quasi-two-dimensional (quasi-2D) perovskites with (Ai)2(A2)n-iPbnX3n+i multi-quantum well structures are considered as the potential electroluminescence (EL) materials due to their controllable quantum confine effect which would lead a high EL efficiency. However, the quasi-2D perovskite films fabricated with solution processing technologies consist of different n phases and orientated layers, which limits the performance of quasi-2D perovskite light- emitting diodes (PeLEDs). To improve the performance of PeLEDs, it is essential to obtain perovskite thin films with both large exciton binding energy, complete surface coverage and suitable morphology. Here some approaches are developed to improve the performance of quasi-2D PeLEDs

Study of golden pompano (Trachinotus ovatus) freshness forecasting method by utilising Vis/NIR spectroscopy combined with electronic nose

Golden pompano (Trachinotus ovatus) quality forecasting method utilising Vis/NIR spectroscopy combined with electronic nose (EN) was investigated in this article. Responses of Vis/NIR spectroscopy and EN to pompanos stored at 4°C were measured for 6 days. Physical/chemical indexes including texture, total volatile basic nitrogen, pH, total viable counts, and human sensory evaluation were synchronously examined as quality references. Chemometric methods including principal component analysis (PCA) and stochastic resonance (SR) were employed for spectroscopic and EN data analysis. Physicochemical examination demonstrated that fish quality decreased rapidly during storage. PCA qualitatively classified freshness degree of pompano samples, while SR signal-to-noise ratio (SNR) spectrum using SNR maximum quantitatively characterised quality for all samples. Golden pompano quality predictive models were developed based on spectroscopy, EN, and spectroscopy combined with EN, respectively. Results demonstrated that the model developed based on spectroscopy combined with EN presented a forecasting accuracy of 93.3%

Investigation on Thermal Degradation Process of Polymer Solar Cells Based on Blend of PBDTTT-C and PC

The effects of thermal treatment on the photovoltaic performance of conventional and inverted polymer solar cells (PSCs) based on the combination of poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b;4,5-b′]dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thie-no[3,4-b]thiophene))-2,6-diyl] (PBDTTT-C) and [6,6]-phenyl C70-butyric acid methyl ester (PC70BM) are investigated. The transient photoconductivity, the absorption spectra, and the transmission electron microscopy (TEM) images have been employed to study the thermal degradation of the inverted PSCs. The degradation is attributed to the inefficient charge generation and imbalance in charge-carrier transport, which is closely associated with the morphological evolution of the active layer with prolonged heating time

Investigation on the Overshoot of Transient Open-Circuit Voltage in Methylammonium Lead Iodide Perovskite Solar Cells

Although the performance of hybrid organic-inorganic perovskite solar cells (PSCs) is encouraging, the detailed working principles and mechanisms of PSCs remain to be further studied. In this work, an overshoot phenomenon of open-circuit voltage (Voc) was observed when the illumination light pulse was switched off. The evolution of the Voc overshoot was systematically investigated along with the intensity and the width of the light pulse, the background illumination, and pretreatment by different bias. Based on the experimental results, we could conclude that the Voc overshoot originated from carrier motion against carrier collection direction, which happened at the ionic-accumulation-induced band bending areas near the interfaces between the perovskite active layer and the two carrier transport layers. The investigation on the Voc overshoot can help us to better understand ionic migration, carrier accumulation, and recombination of PSCs under open-circuit conditions

Pontibacter brevis sp. nov., isolated from rhizosphere soil of Tamarix ramosissima

Osman, Ghenijan, Gao, Yan, Wang, Ning, Mahmud, Otkur, Sun, Jian, Zhang, Tao, Zhan, Faqiang, Zhang, Zhidong, Lou, Kai (2018): Pontibacter brevis sp. nov., isolated from rhizosphere soil of Tamarix ramosissima. International Journal of Systematic and Evolutionary Microbiology 68 (1): 81-86, DOI: 10.1099/ijsem.0.002455, URL: http://dx.doi.org/10.1099/ijsem.0.00245

Study of golden pompano (<i>Trachinotus ovatus</i>) freshness forecasting method by utilising Vis/NIR spectroscopy combined with electronic nose

<p>Golden pompano (<i>Trachinotus ovatus</i>) quality forecasting method utilising Vis/NIR spectroscopy combined with electronic nose (EN) was investigated in this article. Responses of Vis/NIR spectroscopy and EN to pompanos stored at 4°C were measured for 6 days. Physical/chemical indexes including texture, total volatile basic nitrogen, pH, total viable counts, and human sensory evaluation were synchronously examined as quality references. Chemometric methods including principal component analysis (PCA) and stochastic resonance (SR) were employed for spectroscopic and EN data analysis. Physicochemical examination demonstrated that fish quality decreased rapidly during storage. PCA qualitatively classified freshness degree of pompano samples, while SR signal-to-noise ratio (SNR) spectrum using SNR maximum quantitatively characterised quality for all samples. Golden pompano quality predictive models were developed based on spectroscopy, EN, and spectroscopy combined with EN, respectively. Results demonstrated that the model developed based on spectroscopy combined with EN presented a forecasting accuracy of 93.3%.</p

Production of violet pigment by a newly isolated psychrotrophic bacterium from a glacier in Xinjiang, China

A psychrotrophic XT1 strain (CGMCC 1194) isolated from a glacier in China's Xinjiang province produced violet pigments at a high content. This strain was identified as Janthinobacterium lividum XT1 by API kit and 16S rDNA analysis. The main fraction of violet pigment was violacein based on the analysis by HPLC-MS and (1)H NMR. The pigment production by J. lividum XT1 was not associated with the cell growth, and a cultivation temperature lower than 20,C was required for the cell growth and pigment production. Sucrose was the most suitable carbon source, and casein was the best nitrogen source for cell growth and pigment formation. Mineral components in the medium, including CaNO(3), FeSO(4), riboflavin, MgSO(4) and nicotinic acid, showed different effects on the cell growth and pigment production. The maximum pigment productivity reached 0.8 g pigment per dry cell weight. The pigment production pattern by our isolate was different from that by other strains such as J. lividum reported so far. (C) 2008 Elsevier B.V. All rights reserved