Fabrication of Amorphous Silicon-Carbon Hybrid Films Using Single-Source Precursors.

The aim of this study was the preparation of different amorphous silicon-carbon hybrid thin-layer materials according to the liquid phase deposition (LPD) process using single-source precursors. In our study, 2-methyl-2-silyltrisilane (methylisotetrasilane; 2), 1,1,1-trimethyl-2,2-disilyltrisilane (trimethylsilylisotetrasilane; 3), 2-phenyl-2-silyltrisilane (phenylisotetrasilane; 4), and 1,1,2,2,4,4,5,5-octamethyl-3,3,6,6-tetrasilylcyclohexasilane (cyclohexasilane; 5) were utilized as precursor materials and compared with the parent compound 2,2-disilyltrisilane (neopentasilane; 1). Compounds 2-5 were successfully oligomerized at λ = 365 nm with catalytic amounts of the neopentasilane oligomer (NPO). These oligomeric mixtures (NPO and 6-9) were used for the preparation of thin-layer materials. Optimum solution and spin coating conditions were investigated, and amorphous silicon-carbon films were obtained. All thin-layer materials were characterized via UV/vis spectroscopy, light microscopy, spectroscopic ellipsometry, XPS, SEM, and SEM/EDX. Our results show that the carbon content and especially the bandgap can be easily tuned using these single-source precursors via LPD.

Silicon- and Germanium-Functionalized Perylene Diimides: Synthesis, Optoelectronic Properties, and Their Application as Non-fullerene Acceptors in Organic Solar Cells.

Organic solar cells have been continuously studied and developed through the last decades. A major step in their development was the introduction of fused-ring non-fullerene electron acceptors. Yet, beside their high efficiency, they suffer from complex synthesis and stability issues. Perylene-based non-fullerene acceptors, in contrast, can be prepared in only a few steps and display good photochemical and thermal stability. Herein, we introduce four monomeric perylene diimide acceptors obtained in a three-step synthesis. In these molecules, the semimetals silicon and germanium were added in the bay position, on one or both sides of the molecules, resulting in asymmetric and symmetric compounds with a red-shifted absorption compared to unsubstituted perylene diimide. Introducing two germanium atoms improved the crystallinity and charge carrier mobility in the blend with the conjugated polymer PM6. In addition, charge carrier separation is significantly influenced by the high crystallinity of this blend, as shown by transient absorption spectroscopy. As a result, the solar cells reached a power conversion efficiency of 5.38 %, which is one of the highest efficiencies of monomeric perylene diimide-based solar cells recorded to date.

Synthesis and Characterization of Methoxylated Oligosilyl Group 4 Metallocenes.

New methoxylated oligosilyl-substituted metallocenes were synthesized by the reaction of two oligosilanides with different metallocene dichlorides (M = Ti, Zr, and Hf). The first investigated tris(trimethoxysilyl)silanide [(MeO)3Si]3SiK (1) underwent a selective monosubstitution to the respective oligosilyl-decorated metallocenes [(MeO)3Si]3SiMClCp2 (2-4). Surprisingly, the attempted disilylation with this silanide was not possible. However, in the case of titanocene dichloride, a stable radical [(MeO)3Si]3SiTiCp2 (5) was formed. The unsuccessful isolation of bisilylated metallocenes encouraged us to investigate the reactivity of another silanide. Therefore, we synthesized a hitherto unknown disilanide K[(MeO)3Si]2Si(SiMe2)2Si[(MeO)3Si]2K (8), which was accessible in good yields. The reaction of compound 8 and different metallocene dichlorides (M = Ti, Zr, and Hf) gave rise to the formation of heterocyclic compounds 9-11 in good yields.