Transient photocurrent of (silicon nanocrystals)–(organic polysilane) composites—detection of surface states of silicon nanocrystals

Transient photoconduction of thin films of Si nanocrystals (nc-Si) dispersed in poly(methylphenylsilane) (PMPS) matrix prepared by printing have been studied by means of time-of-flight (TOF) measurements. Addition of nc-Si whose average diameter is 27 nm to PMPS induces percolative transport through nc-Si, and the percolation threshold of the transport of nc-Si in PMPS matrix is 9.4 wt.% of nc-Si. Below the threshold, hole TOF photocurrent transients are clearly observed, indicating that the hole transport path is PMPS matrix. Localized-state distributions are derived from the analysis based on Laplace transform of the hole transient photocurrent below the threshold and originate in the surface states of nc-Si. TOF measurements of such nanocrystal-polymer composites are therefore suitable for the study of surface-state distributions of semiconductor nanocrystals.