Mono-, oligo- and poly-3-(1,1-difluoroalkyl)thiophenes and their use as charge transport materials

A monmeric, oligomeric, or polymeric [3-(1,1-difluoroalkyl)thiophene] compound comprising one or more identical or different recurring units of formula I

• —[(Y)a—(D)b—(Z)c]— I
• wherein
• D is a 3-(1,1-difluoroalkyl)thiophene group of formula II
• R1 is H, straight chain, branched or cyclic alkyl with 1 to 20 C-atoms, which is unsubstituted, mono- or partially-substituted by F, Cl, Br, I, —CN or —OH, wherein optionally one or more non-adjacent CH2 groups is replaced, in each case independently from one another, by —O—, —S—, —NH—, —NR0—, —SiR0R00—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —CH═CH— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, or optionally substituted aryl or optionally substituted heteroaryl,
• R2 is H, F, straight chain, branched or cyclic alkyl with 1 to 20 C-atoms, which is unsubstituted, mono- or poly-substituted by F, Cl, Br, I, —CN or —OH, wherein optionally one or more non-adjacent CH2 groups is replaced, in each case independently from one another, by —O—, —S—, —NH—, —NR0—, —SiR0R00—, —CO—, —COO—, —OCO—, —OCO—O—, —CO—, —CO—S—, —CH═CH— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, or optionally substituted aryl or optionally substituted heteroaryl,
• R0 and R00 are independently of each other H or alkyl with 1 to 12 C-atoms,
• Y and Z are independently of each other —CX1═CX2—, —C≡C—, or optionally substituted arylene or heteroarylene,
• X1 and X2 are independently of each other H, F, Cl or CN, and
• a, b and c are independently of each other 0 or 1, with a+b+c>0, and wherein in at least one recurring unit b is 1,
• wherein if n and b both equal 1 and a and c both equal 0, then at least one of the terminal groups of the compound is not H.