PHOTOCONDUCTIVITY OF POLY(METHYLPHENYL SILYLENE) DOPED WITH DINITROBENZENES

Poly(methylphenyl silylene) PMPSi was doped with the following compoun ds of the electron acceptor type: p-dinitrobenzene (pDNB), m-dinitrobe nzene (mDNB), and o-dinitrobenzene (oDNB), up to concentrations of 3 m ol%. The quantum yield of charge carrier generation phi(cc) is signifi cantly increased, relative to that of neat PMPSi, by pDNB (about four times at a field F = 2 x 10(7) V m(-1) and 3 mol%. mDNB and oDNB exert only a small effect on phi(cc). The extent of increase in phi(cc) is correlated with the electron affinity EA; both of them increase in the order oDNB < mDNB < pDNB. On the other hand, the hole drift mobility Fl is influenced by the dipole moment p of the dopants. mu is increase d by pDNB (p approximate to 0 D) and decreased by mDNB (p approximate to 3.8 D) and oDNB (p approximate to 6.0 D). It is concluded that addi tives with p > 0 interact (probably electrostatically) with holes pass ing through the polymer matrix. This results in an increase in the act ivation energy of mu or, in terms of the hopping transport model, in a broadening of the distribution of energy states of transporting sites or even in a change in the character of the distribution function. Re quirements for dopants of the electron acceptor type regarding optimum improvement of the photoconductive properties of PMPSi are: low p val ues (close to zero) and high EA values.