Sensitizer Effects on the Transport Properties of Polymer:Sensitizer Organic Blend

Abstract

AbstractIn this work we studied the effect of sensitizer concentration on a mobility-lifetime product μτ, on photoconductivity response time ph τph, and on drift mobility μ of the majority carriers in an organic polymer:sensitizer blend. The intensity modulated photocurrent and photo-EMF technique were used as experimental tools for this purpose. The studied material consists of a mixture of the novel non-conjugated main chain hole-transporting polymer PFO6:PDA (Poly(N,N'-bis(4-hexyloxyphenyl)-N'-(4-(9-phenyl-9H-fluoren-9-yl)phenyl)phenylen-1,4- diamine) sensitized with the highly soluble C60 derivative PCBM (phenyl-C61-butyric acid methyl ester) in the range from Z = 1 to 40 wt.-%. It was experimentally observed that (1) at the increasing sensitizer concentration the overall photoconductivity increases; (2) the majority carrier type switches from holes to electrons at approximately 2:1 polymer:sensitizer ratio; (3) the holes response time becomes shorter at the decreasing polymer fraction, while the electrons lifetime is only slightly dependent on sensitizer concentration; (4) the hole mobility-lifetime product decreases at the decreasing concentration of hole transporting component (polymer), while the electrons mobility-lifetime product increases at the increasing concentration of the electron transporting component (sensitizer); (5) the same is true for the carriers mobilities.