NOVELTY - Polymerizable liquid crystal (LC) material (m1) comprises 1-45% of at least one 1,4-bis-phenylethynyl-benzene derivative (I), and 50-99% of polymerizable mesogenic or liquid crystalline compounds other than the compound (I).    USE - For making polymer film in an optical, electronic or electrooptical device or their components selected from electrooptical displays, LCDs, optical films, polarizers, compensators, beam splitters, reflective films, alignment layers, color filters, holographic elements, hot stamping foils, colored images, decorative or security markings, LC pigments, adhesives, non-linear optic (NLO) devices, optical information storage devices, electronic devices, organic semiconductors, organic field effect transistors (OFET), integrated circuits (IC), thin film transistors (TFT), Radio Frequency Identification (RFID) tags, organic light emitting diodes (OLED), organic light emitting transistors (OLET), electroluminescent displays, organic photovoltaic (OPV) devices, organic solar cells (O-SC), organic laser diodes (O-laser), organic integrated circuits (O-IC), lighting devices, sensor devices, electrode materials, photoconductors, photodetectors, electrophotographic recording devices, capacitors, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates, conducting patterns, photoconductors, electrophotographic applications, electrophotographic recording, organic memory devices, biosensors, biochips, optoelectronic devices requiring similar phase shift at multiple wavelengths, combined CD/DVD/HD-DVD/Blu-Rays, reading, writing re-writing data storage systems, or cameras (all claimed).    ADVANTAGE - The polymerisable LC material (m1) and the polymer film have a negative retardation dispersion, and a birefringence of greater than or equal to 0.05 or less than 0.15 (preferably greater than or equal to 0.035 or less than 0.1) at 550nm. The 1,4-bis-phenylethynyl-benzene derivative (I) show a high negative optical dispersion, achieves negative dispersion in the final LC mixture of polymer film even when used at lower concentrations compared to the compounds and materials of prior art; thus reduce the costly negative dispersion component in the polymer film and reduce the manufacturing costs.    DETAILED DESCRIPTION - Polymerizable liquid crystal (LC) material (m1) comprises 1-45% of at least one 1,4-bis-phenylethynyl-benzene derivative of formula (I), and 50-99% of polymerizable mesogenic or liquid crystalline compounds other than the compound (I).    U1 and U2=groups of formulae (ia)-(ic) or their mirror images, (where the rings U1 and U2 are bonded to the central bitolane group via the axial bond, at least one non-adjacent CH2 group in these rings are optionally replaced by O and/or S, and the rings U1 and U2 are optionally substituted by at least one group L);    Q1 and Q2=CH or SiH;    Q3=C or Si;    A1-A4=non-aromatic carbocylic or heterocyclic groups and aromatic or heteroaromatic groups, (all optionally substituted by at least one group R5);    Z1-Z4=-O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR0-, -NR0-CO-, -NR0-CO-NR0-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2- -CH2CH2-, -(CH2)3-, -(CH2)4-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=CH-, -CY1=CY2-, -CH=N-, -N=CH-, -N=N-, -CH=CR0-, -C?=C-, -CH=CH-COO-, -OCO-CH=CH-, CR0R00 or single bond;    Y1 and Y2=H, F, Cl, CN or R0;    R0 and R00=H or 1-12C alkyl;    m-p=O-4;    R1-R5=1-40C (hydro)carbyl (optionally substituted and optionally comprises at least one hetero atom, or denote P' or P'-Sp-, or are substituted by P' or P'-Sp-), H, halo, -CN, -NC, -NCO, -NCS, -OCN, -SCN, -C(=O)NR0R00, -C(=O)X0, -C(=O)R0, -NH2, -NR0R00, -SH, -SR0, -SO3H, -SO2R0, -OH, -NO2, -CF3, -SF5, P-Sp-, or optionally substituted silyl;    P'=polymerizable group;    Sp=spacer group or single bond.    The -(A1-Z1)m-U1-(Z2-A2)n- and -(A3-Z3)o-U2-(Z4-A4)p- does not contain more aromatic groups than non-aromatic groups). The compounds comprise at least one group R1-R4 that denotes P' or P'-Sp- or is substituted by P' or P'-Sp-. INDEPENDENT CLAIMS are included for the following:    (1) polymer film obtained by polymerizing the polymerisable LC material (m1); and    (2) optical, electronic or electrooptical device, or its component comprising the polymerisable LC material (m1) or the polymer film.