Photoconduction of (silicon nanocrystals)–(organic polysilane) composites

Photoconduction of thin films of Si nanocrystals (nc-Si) dispersed in poly(methylphenylsilane) (PMPS) matrix prepared by printing has been studied by means of steady-state photoconductivity and time-of-flight (TOF) transient photocurrent measurements. Addition of nc-Si whose average diameter is 27 nm to PMPS induces photoconductive response in a visible spectral range from 1.9 to 3.35 eV, where no photoconductive response is observed in pristine PMPS. The dark current–voltage, steady-state photoconductivity and TOF measurements indicate that the roles of nc-Si and PMPS in nc-Si/PMPS composites are photocarrier generation and photocarrier transport, respectively. The TOF transient photocurrent measurements reveal that the hole drift mobilities of the composite are essentially unaffected in the nc-Si concentration range from 0 to 5 wt.% but nc-Si addition increases energetic disorder. The increase in energetic disorder is attributable to surface states of nc-Si.