Super-hierarchiral quantum effects and semiconducting polymers with 14-group elements (1): VIS-NIR photoluminescence from 2D-polysilyne with quantum confinement effects

Si crystal Si is a typical non-luminous semiconductor due to indirect band gap of 1.1eV, while one-dimensional polysilane is a highly luminous polymer due to direct band gap of 3.2-3.9eV. Herein we report that pyrolitic product of two-dimensional n-butyl polysilyne turned to highly luminous amorphous silicon-like materials (Raman Si-Si band 460cm-1), emitting 460-750nm (1.6-2.7eV). The emitting wavelengths were easily controlled by the choice of pyrolytic temperature and time of the polysilyne sealed in vacuo. Of particular interest is that i-butyl polysilyne afforded crystalline Si (Raman Si-Si band 510cm-1 typical for crystal Si), when i-butyl polysilyne was treated at 500C in vacuo. These findings are very promising in developing novel highly lumiuous Si-related materials and Si thin film without the use of dangerous SiH ₄ gas.