Reactive mesogenic benzodithiophenes

A reactive mesogenic benzodithiophene according to formula I

• P-Sp-X-T-R I
• wherein
• P is a polymerisable or reactive group,
• Sp is a spacer group or a single bond,
• X is a linkage group or a single bond,
• R is H, halogen, CN, NO2, an aliphatic, alicyclic or aromatic group with up to 40 C atoms that optionally comprises one or more hetero atoms and wherein one or more rings can be fused, or P-Sp-X—, and
• T is a mesogenic group comprising one or more benzodithiophene groups, wherein the benzodithiophene groups benzo[1,2-b:4,5-b′]dithiophene groups, selected from formula II
• -Z1-(A1-Z2)m-(T1-Z3)n-(A2-Z4)o- II
• wherein
• A1 and A2 are independently of each other an aromatic, heteroaromatic or alicyclic group with up to 18 C atoms which is unsubstituted, mono- or polysubstituted with R1, and A1 may also denote T1,
• Z1 to Z4 are independently of each other —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR0—, —NR0—CO—, —OCH2—, —CH2O—, —SCH2—, —CH2S—, —CF2O—, —OCF2—, —CF2S—, —SCF2—, —CH2CH2—, —CF2CH2—, —CH2CF2—, —CF2CF2—, —CH═N—, —N═CH—, —N═N—, —CH═CR0—, —CY1═CY2—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH— or a single bond,
• Y1 and Y2 are independently of each other H, F, Cl or CN,
• T1 is a group consisting of 1 or 2 benzodithiophene units which are optionally substituted by R1,
• R1 is H, halogen, CN, NO2, straight chain, branched or cyclic alkyl with 1 to 20 C-atoms, which is unsubstituted, mono- or polysubstituted by F, Cl, Br, I or CN, and wherein one or more non-adjacent CH2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NH—, —NR0—, —SiR0R00—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —CY1═CY2— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, an aromatic or heteroaromatic group, or P-Sp-X,
• R0 and R00 are independently of each other H or alkyl with 1 to 12 C-atoms,
• m and o are independently of each other 0, 1, 2 or 3, and
• n is 1, 2 or 3,
• wherein at least one of said benzodithiophene units of T1 is substituted by R1.