Liquid-phase crystallization (LPC) has proven to be a suitable method to grow large-grained silicon films on commercially well-available glass substrates. Zone-melting crystallization with high-energy-density line sources such as lasers or electron beams enabled polycrystalline grain growth with wafer equivalent morphology. However, the electronic quality is strongly affected by the material used as the interlayer between the glass and the silicon absorber. Open-circuit voltages above 630 mV, and efficiencies up to 11.8% were demonstrated using n-type absorbers on a sputtered interlayer comprising a triple stack of SiO 2 /SiN x /SiO 2 . In this study, we present our results to further improve the device performance by investigating the influence of the interlayer on the open-circuit voltage of the devices and characterize the properties of the absorber and interface using bias light-dependent quantum efficiency data and transmission electron microscopy (TEM) images. Finally, we investigate the applicability of aluminum oxide (Al 2 O 3 ) for passivation of p-type LPC absorbers.

Intramolecular [2 + 2] photoannulation catalysed by copper(I)triflate has been applied to a series of carbohydrate derivatives obtained from glucose. Dienes 1a and 1b lead to cyclobutanes 3a and 3b whereas the diastereoisomeric dienes 5a and 5b gave diastereoisomeric products 7a and 7b. These results demonstrate that the reaction is stereospecific. Products 3a and 7a were converted into bromoesters 4 and 9 respectively. The Vasella elimination of 8 lead to the expected bicyclic aldehyde 10 and the ring expanded hydroxy ketone 12. The stereospecific formation of enantiomerically pure spiro annulated carbohydrates 18a and 18b was demonstrated whereas in example 19 no selectivity in the formation of 20 and 21 was observed.

A general strategy is proposed, wherein a pentose sugar gamma-lactone can be converted, via a series of nine reactions, to a 3,4-dihydroxyproline, suitably protected for use in peptide synthesis. Thus, D-ribonolactone (6) has been converted to N-fluorenylmethoxycarbonyl-3,4-di-O-tert-butyldimethylsilyloxy-D-2,3-cis-3,4-cis-proline (7) in 18.9% overall yield. Likewise, L-arabinonolactone (11) has been converted to N-fluorenylmethoxycarbonyl-3,4-di-O-tert-butyldimethylsilyloxy-L-2,3-cis-3,4-trans-proline (36) in 13.7% overall yield and L-lyxonolactone (12) to N-fluorenylmethoxycarbonyl-3,4-di-O-tert-butyldimethylsilyloxy-L-2,3-trans-3,4-cis-proline (37) in 11.2% overall yield. These building blocks have also been fully deprotected to give the free amino acids. We believe that this series of reactions ought to be applicable to the synthesis of any of the eight stereoisomers of 3,4-dihydroxyproline, by judicious selection of the pentose starting material.

Ring-closing metathesis has been applied to a series of glucose derivatives to produce cyclopentene derivatives 5a and 5b, cyclohexene derivatives 8 and 9, cycloheptene 12, and cyclooctene 14. Spirocyclic dihydrofurans 19, 26a, and 26b, along with dihydropyran 22, were also produced. A range of fused oxepine derivatives 29a-c and one oxo-cyclononene 31 were also prepared. Cyclopentene 5b was subjected to a sequence of hydrogenation, NBS bromination, and treatment with powdered zinc to furnish the ring-expanded product 35. No such ring expansion occurred when the cyclohexaannulated compound 8 was treated with NBS followed by powdered zinc, leading to aldehyde 39. The spiro dihydrofuran derivative 19 was converted to the aldehyde 42 via the same reaction sequence used to fragment cyclopentene derivative 5b.

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Carbohydrate derivatives 1a, 1b, 3a and 3b have been subjected to copper(I) catalysed photoannulation to produce tetracyclic products 2a, 2b, 4a and 4b respectively as single enantiomers. The same reaction carried out on substrates 5a and 5b leads stereoselectively to the spiro products 6a and 6b respectively. Photoannulation of substrate 7 gave an approximate 1:1 mixture of spiro products 8 and 9. A mechanistic rationalisation of these results is proposed.

Selbst achtgliedrige Ringe entstanden (wie in 2) bei Ringschlußmetathesen aus Glucosederivaten wie 1. Auch tricyclische Spiroverbindungen wurden enantiomerenrein erhalten.

Even eight-membered rings (such as in 2) can be formed by ring-closing metathesis of glucose derivatives such as 1. Enantiomerically pure tricyclic spiro compounds can also be prepared.