Fluorocarbon-Modified Organic Semiconductors:Molecular Architecture,Electronic,and Crystal Structure Tuning of Arene-versus Fluoroarene-Thiophene Oligomer Thin-Film Properties

摘要

We present here the systematic synthesis and comparative physicochemical characterization of a series of regiochemically varied and core size extension-modulated arene(perfluoroarene)-thiophene oligomers.The molecules investigated are:5,5"-diphenyl-2,2':5',2":5",2'''-quaterthiophene (1),5,5'-bis-{1-[4-(thien-2-yl)phenyl]}-2,2'-dithiophene (2),4,4'-bis[5-(2,2'-dithiophenyl)]-biphenyl (3),5,5"-diperfluo-rophenyl-2,2':5',2":5",2'"-quaterthiophene (4),5,5'-bis{ 1 -[4-(thien-2-yl)perfluorophenyl]}-2,2'-dithiophene (5),4,4'-bis[5-(2,2'-dithiophenyl)]-perfluorobiphenyl (6),5,5"-diperfluorophenyl-2,2':5',2"-tertthiophene (7),5,5'-diperfluorophenyl-2,2'-dihiophene (8),and 5,5-diperfluorophenylthiophene (9).Trends in optical absorption and emission parameters,molecular structures as defined by single-crystal X-ray diffraction,as well as electrochemical redox processes are described.The morphologies and microstructures of the vapor-deposited films grown over a range of growth temperatures have also been characterized.Field-effect transistor (FET)measurements demonstrate that all of these materials are FET-active and,depending on the molecular architecture,exhibit comparably good p-or n-type mobility when optimum film microstructural order is achieved.A very large n-channel mobility of approx0.5 cm~2/Vs with I_(on)/I_(off)ratios > 10~8 is achieved for films of 4.