Increased carrier mobility in end-functionalized oligosilanes

Abstract

A class of hybrid oligosilane–arene materials outperforms the σ- and π-conjugated parent structures.

Photoinduced Charge Separation in Molecular Silicon

“…An arresting feature of 1 a – c is their yellow color in solution and in the film state . In contrast, permethylated oligosilanes and carbon‐based analogues 2 and 3 a are colorless, implicating the silicon chain as an essential contributor to the photophysical properties of the hybrid materials.…”

“…DFT and TF‐DFT calculations indicate that the low‐energy side of this feature is associated with a HOMO‐LUMO transition, with the HOMO localized predominantly on the electron‐rich silanyl core and the LUMO on the cyanovinyl end groups. Transitions localized on only the cyanovinyl moiety are predicted to fall at higher energies . The position of maximum absorbance varies only weakly with solvent polarity.…”

“…Yet molecular silicon presents significant attractive opportunities for materials: similar to the bulk semiconductor, it is earth abundant, and the unique tetrahedral and flexible structure of an oligosilane chain lends itself to new and distinct architectures in molecular electronics. Inspired to explore the structural diversity of molecular silicon semiconductors, we recently described the synthesis and electronic characterization of a new class of hybrid organosilicon materials 1 a – c (Scheme ) . Record‐setting mobilities for a device with an oligosilanyl active layer (up to 0.06 cm 2 V −1 s −1 ) were observed and attributed in part to a crystal‐packing structure inaccessible to all‐organic analogs.…”

2D Oligosilyl Metal–Organic Frameworks as Multi‐state Switchable Materials

“…Herein, we present two examples of MOFs capable of reversible structural transformations between multiple crystalline or amorphous phases. Oligosilanes, molecules with Si−Si bonds, are a class of hybrid inorganic‐organic materials with remarkable light absorption and charge transport properties that uniquely combine flexibility and strong light absorption, a property that inspired us to construct 2D MOFs based on oligosilyl linkers. While organosilicon species have been previously used in MOF formation, the organic linker usually contains a single Si atom, which precludes access to properties inherent to σ‐conjugated extended oligosilanes.…”

Synthesis of a Fragment of Crystalline Silicon: Poly(Cyclosilane)

“…The application of rational synthesis to organic materials chemistry leads to the isolation of innovative and well-defined materials inaccessible by top-down methods. [5,6] Current efforts focus on organic side chains: hybrid s,p-silanes are efficient hole transport materials [7] and undergo intramolecular photoinduced charge transfer, [8] donor-acceptor systems display nonlinear optical behavior, [9,10] and stereogenic centers or fluorinated groups control the global conformation and absorbance properties in helically chiral polysilanes. [4] Yet increased structural complexity in polysilanes has great potential to lead to novel properties.…”