CZTS

There are currently two basic approaches to fabricate GZTS layers by electrodeposition. In the stacked elemental (SEL) approach, the parent metals are electrodeposited sequentially to form a stack [35, 119] which is then annealed in a sulfur atmosphere to from CZTS. In an alternative approach, the parent metals are co-deposited to form a mixed metallic or alloy layer which is then annealed in the presence of sulfur [120, 121]. Both approaches have yielded cells with AM 1.5 efficiencies of over 3%. 

1 Fabrication of Thin-Film Solar Cells via the SEL Method 

The SEL approach has some advantages over co-deposition, because it allows simpler coulometric control of the precursor stoichiometry. The SEL method may also be more suitable for large-scale fabrication since there is no requirement to balance the deposition rates of several different metals, so higher current densities can be used. If an alloyed precursor is preferred for the sulfur annealing step, a short ( 5min) heat treatment at 200-350 °C is sufficient to completely alloy the stacked precursor. In this section, we highlight some of our recent work on the fabrication of CZTS solar cells by the SEL route [11]. 

Growth of Zinc Layers The morphology of the Zn layer is strongly influenced by the structure of the underlying Sn layer. Although excellent Zn films could be grown on Cu layers, nucleation of Zn on Sn layers was found to be very uneven. 

The best device gave an open circuit voltage (VoJ of 480 mV, a short circuit current density (Jsc) of 15.3mAcm and a fill factor of 45%. The corresponding power conversion efficiency was 3.2%, which is similar to the values reported by Araki et al. (3.16% [120]) and Ennaoui et al. (3.4% [121]). 

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Oxymercuration of 4-f-butylcyclohexene, followed by NaBH4 reduction, gives czT-4-f-butylcyclohexanol and frans-3-f-butylcyclohexanol in approximately equal amounts. l-Methyl-4-f-butylcyclohexanol under similar conditions gives only czT-4-f-butyl-l-methylcyclohexanol. Formulate an explanation for these observations. 

The formation of bicyclo[3.1.0]hex-2-enes is a common reaction of cyclic and acyclic cZt-l,3,5-trienes. While it has been frequently depicted as a [n4 + tt2]-cycloaddition and it often exhibits the stereochemistry expected of a concerted [zr4s + rr2a] process109, it is well known that it just as often does not. The stereochemistry, conformational requirements and scope of the reaction have been thoroughly studied by a number of workers, and have been extensively reviewed116,128,170 172. 

In general, the regiochemistry of the reaction is such that the more highly substituted terminal carbon of the 1,3,5-hexatrienyl moiety (e.g. of 138) ends up as C6 of the bicyclo[3.1.0]hex-2-ene structure (139) while with 2-substituted trienes having identically substituted terminal carbons, such as 140, the cyclopropyl group is formed at the opposite end of the system (cf 141, equation 52)188,210. This is mainly due to steric factors which stabilize one cZt conformer relative to the other. 

Simulation of the difference signal using known theoretical and experimental structures of the 1,3,5-hexatriene product molecules matches the observed signal to within 10%, without the use of any adjustable parameters. Our fit indicates that the molecule opens up to the completely open tZt form of 1,3,5-hexatriene, within about 20 ps. Within the noise of our instrument, there is no indication for any intermediate existence of the cZt or cZc forms of hexatriene. 

The amount of catalyst (scandium trisdodecyl sulfate) and ligand, (14), in the ring opening of czT-1,2-disubstituted oxiranes with primary and secondary aromatic amines in water were varied to maximize the yields.33 In all but two cases, the reaction, under ideal conditions, yielded the j3-amino alcohols in >81% yield with enantioselectivity ... 

Fig. 5.35 TC6 of zirconate compositions with varying titanium contents (CZT CaZr03, CaTi03 SZT SrZr03-SrTi03 (measured at 4 GHz).

Tautomeric equilibrium in aqueous cw-malonaldehyde, see reaction 1 in Figure 8-4, is a prototypical reaction extensively studied in the gas phase but still relatively unknown in solution. In fact, despite the large number of NMR experiments [52,53,54] and quantum chemical calculations [55] with the polarized continuum model (PCM), [1] the actual stability of czT-malonaldehyde is not well clarified, although the trans isomer should be the predominant form in water. Secondly, the involvement of the light proton in the reaction may in principle provide relevant quantum effects even in condensed phase. All these complications did not prevent this reaction to be used as a prototypical system for theoretical studies of intramolecular proton transfer in condensed phase by several investigators [56,57,58,59,60] including ourselves. 

S YNS 1 -(2-CHLOROETHYL)-3-(d-GLUCOPYRANOS-2-YL)-l-NITROSOUREA 2-((((2-CHLOROETHYL)NITRO-SOAMINO)CARBONYL)AMINO)-2-DEOXY-d-GLUCOPYRANOSE 2-((((2-CHLOROETHYL)NITROSO-AMINO)CARBONYL)AMINO)-2-DEOXY-d-GLUCOSE 2-(3-(2-CHLOROETHYL)-3-NITROSOUREIDO)-2-DEOXY-d-GLUCOSOPYRANOSE 2-(3-(2-CHLOROETHYL)-3-NITROSOUREIDO)-d-GLUCO-PYRANOSE CHLZ CZT DCNU NSC-178248 NSC-D 254157... 

Pelite Domain 11 qz-bi-grt-hbl-An23. sj-chit-muso-czt-cc-tourm-ilnn 3 065, 10.470 049, 49.820... 

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