Optical Properties of Silicon Nanosheets Modified with Triphenylamine and Quinoline Units: Charge and Energy Transfer from Conjugated Substituents to the Catenated Silicon Backbone

The optical properties of triphenylamine- and quinoline-containing silicon nanosheets prepared by treatment of layered polysilane (Si6H6)(n) with p-(aminomethyl)-triphenylamine and 4-(aminomethyl)quinoline, respectively, were examined with regard to their UV-vis absorption and photoluminescence spectra. The triphenylamine-containing nanosheet generated photoluminescence bands around 370 and 420 nm. The low-energy band was intensified and red-shifted with increasing solvent polarity, indicating intramolecular charge transfer from the triphenylamine unit to the catenated silicon backbone in the photoexcited state. In the case of the quinoline-containing nanosheet, efficient photoenergy transfer from the aromatic substituents to the silicon layer was observed.