Transport and stability of doped freestanding silicon nanocrystals and MEH-PPV blends

We report on optoelectrical properties of freestanding silicon nanocrystals (Si-ncs) in poly[methoxy-ethylexyloxy-phenylenevinilene] (MEH-PPV). Electrochemical etching and pulverization of fine porous silicon films are used to prepare surfactant free boron- and phosphorous-doped Si-ncs with the same size distribution. We studied doped-Si-ncs/MEH-PPV blends with high concentrations of the Si-ncs in the matrix. A considerable increase of dark conductivity is observed when doped Si-ncs are introduced in the polymer. We find that the studied blends show a higher stability compared to pure polymer films. The results obtained can be explained by the reduction of the formation of carbonyl type groups in MEH-PPV and of the oxygen diffusion inside of the polymer matrix. Improved stability of the composites makes them as an attractive material for no-toxic solar cell production.