We have investigated the transport properties of organic field effect transistors (OFETs) with quantum dot layers between the organic semiconductor and the dielectric. An insulating dot layer changes the properties of OFETs, suggesting that OFET mobility will always be reduced by additional physical disorder. However, a metal dot layer causes a much larger reduction of the mobility and an increase of the activation energy. This phenomenon may be explained by more charge being induced on metal dots causing the carriers to be more localized.
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The authors are grateful to C. Daniel Frisbie and Yu Xia for useful advice and for sample preparation. This work was supported in part by the U.S. Department of Energy under Grant No. DE-FG02-02ER46004 and by the National Science Foundation through the University of Minnesota Materials Research Science and Engineering Center under Grant No. NSF/DMR-0212032.