Influence of Urbach Energy,Temperature, and Longitudinal Position in the Active Layer on Carrier Diffusion Length in Perovskite Solar Cells

The diffusion length of charge carriers in the active layer of a perovskite solar cell (PSC) of the structure Glass/PEDOT: PSS/CH₃NH₃PbI₃/PC60BM/Al is modelled. It is found that the diffusion length depends on the position x in the active layer measured from the PEDOT: PSS interface, Urbach energy and temperature. By varying the voltage in the range from zero to , it is shown that the dependence of diffusion length on the position x in the active layer reduces at higher voltage. The combined influence of applied voltage and temperature on the diffusion length of charge carriers is investigated and it is found that in the low voltage range the diffusion length is temperature independent, but it becomes significantly temperature dependent at higher voltages. Also, it is found that the diffusion length decreases as the applied voltage increases and this reduction becomes much more significant at higher voltage and temperatures. The combined influence of applied voltage and Urbach energy on diffusion length of charge carriers reveals that the diffusion length decreases when both the applied voltage and Urbach energy increase. However, the reduction in the diffusion length due to the increase in Urbach energy becomes less significant at higher voltage.     

Chiroptical detection during liquid chromatography,part 5: On-line measurement of circular dichroism spectra Δε(λ) during stops of chromatographic flow

Summary A procedure is described which serves to measure circular dichrograms () on line during stops of flow in liquid chromatography. Since the concentration of substrate in the spectrometer cell during the stop is not known, the differential absorption coefficients are calculated from the experimental differential absorbances A by means of UV absorption (i. e. photomultiplier voltage) data. Verifications of the procedure are obtained by its application to three substrates (Table 1), the () spectra of which were known. The present on-line technique is compared with a corresponding off-line method.The N,N-dimethylthiobenzamides1 and2 as well as the 9,10-phenanthrenequinone7 consist of interconvertible enantiomers because their planar states are destabilized by steric overcrowding of groups. The unknown dichrograms () of1, 2 and7 are obtained (Figs. 2 and 4) and discussed with reference to the helicities of these molecules.In memory of the late Professor Dr. Dr. h. c. Günther Snatzke.     

Influence of two grinding methods on the uncertainty of determinations of heavy metals in atomic absorption spectrometry/electrothermal atomisation of plant samples

 Chemical analyses of trace elements are affected by relatively high analytical errors due to the different steps of the laboratory procedures: samples grinding, mineralisation and instrumental measurements. In the present communication, the influence of the grinding phase on the global uncertainty of Pb, Cd, Ni and Cr determinations in plant samples by the classical method of atomic absorption spectrometry/electrothermal atomisation (AAS-ETA) after dry ashing is quantified. Two grinding machines, a planetary mill with balls and jars of agate versus a stainless steel grinder were compared by analysing leaf samples of cucumber, strawberry, kiwivines, apple trees and grapevines from agricultural experimental plots under controlled conditions. Variance components due to the difference between grinding methods and experimental plots were estimated. Further, the simultaneous effects of the grinding methods on all considered metals have been evaluated by analysis of variance. With the stainless steel grinder, on average, higher levels of the considered heavy metals were obtained (up to 67% of the mean values). On average, the increments were similar for metals contained in steel (Ni and Cr) and those not contained (Pb and Cd). The true causes of these differences need further investigation to determine whether the higher metal detection is due to possible contamination, to a different grinding quality or to other reasons. Finally, the grinding methods did not seem to affect the combined uncertainty of the analyses. Received: 3 November 1997 · Accepted: 29 November 1997     

Advances in two-dimensional GC with glass capillary columns

A versatile two-dimensional gas chromatograph is described, consisting of 2 separate ovens, one intermediate trap, an auxiliary inlet, and the necessary hardware to effect off-line switching according to the principle of Deans. The unit has been designed for use with high resolution glass capillary columns. The performance of individual instrumental components was critically evaluated. Results showed that low dead volume glass to metal connections were required in the manifold and detector lines to minimize extra-column effects. The mass of the intermediate trap must be low to allow rapid heating. Operational parameters are discussed and examples of some applications are shown.     

Analysis of Early Medieval Glass Beads – The Raw Materials to Produce Green, Orange and Brown Colours

 Monochrome coloured glass beads of the Merovingians (5^th–7^th cent. AD) have been examined by different analytical methods. The elemental composition of a large number of mostly unprepared beads have been measured non-destructively by X-ray fluorescence analysis. After subtracting the content of the colouring oxides of the glass beads and normalising the residual values to 100% an identical soda-lime-glass matrix was obtained. X-ray diffraction was used for the identification of the crystalline colouring and opacifying pigments (SnO₂, Cu, Cu₂O, PbSnO₃), and scanning electron microscopy as well as electron probe microanalysis were applied to study the microstructure and the composition of white, brown, green, orange and yellow coloured glass beads. Oxidised metals, alloys (lead, copper, bronze, brass and mixtures of them) and iron smelting slag have been identified as raw materials to colour the soda-lime-glass.     

TPSR STUDIES OF THE ACTIVATION OF METHANE ON SUPPORTED PLATINUM CATALYSTS

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乙醇羰化反应负载型催化剂的研究

本文由七种负载型催化剂中选出两种比较好的乙醇羰化催化剂,研究了影响反应转化率和选择性的因素,考察了活性组份的价态和载体的酸性。此外,还对催化剂进行了能量色散X射线分析。从其结果看,谱图上只有活性中心铑的谱峰而没有氯的谱峰,说明铑是以离子形式进入载体,而不是以化合物形式被吸附于载体上。     

Synthesis and structure of the 1,2-isopropylidene-α-D-glucofuranose 3,5,6-bis-cyclophosphite complex with tungsten(0) pentacarbonyl

Metallocomplexes with optically active ligands are of considerable interest as catalysts of stereoselective processes. A complex of 1,2-isopropylidene-α-D-glucofuranose 3,5,6-bis-cyclophosphite with tungsten(0) pentacarbonyl has been synthesized for the first time and studied by X-ray crystallography.     

STUDY ON 1-HEXENE POLYMERIZATION BASED ON ZIEGLER-NATTA CATALYSTS WITH DOPED SUPPORT

A series of Ti/Mg supported catalysts are prepared by using ball-milled mixtures of MgCl2-ethanol adducts and NaCl as supports, and 1-hexene polymerizations catalyzed by the novel catalysts are studied. It is found that the molecular weight distribution of poly(1-hexene) becomes apparently narrower when catalysts with doped supports are used, indicating that changing the structure of the support is an effective way to regulate the active center distribution of heterogeneous Ziegler-Natta catalyst.     

Chemisorption of SO2 and Cl2 on indium oxide

The mutual influence of SO₂ and Cl₂ during their consecutive chemisorption on the In₂O₃ surface has been investigated. It was found that SO₂ is chemisorbed in the uncharged form, and the amount of chemisorption decreases as the temperature increases. The preliminary chemisorption of Cl₂ results in a dramatic decrease in the amount of SO₂ sorbed and in a change in the character of the bonding of SO₂ with the oxide surface. When SO₂ is sorbed first, the temperature of the formation of chlorides during subsequent chemisorption of Cl₂ decreases.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1718–1721, October, 1994.