Ink composition, film using the same, and electrophoretic display device

An ink composition comprising:

• a semiconductor nanorod;
• and
• a dispersion medium comprising:
• a first compound represented by one of Formulae 4-1 to 4-3 and having a dielectric constant of about 4 to about 7.5;
• and
• at least one additional compound selected from among:
• (a) a second compound represented by one of Formulae 1-1 to 1-5 and having a dielectric constant equal to greater than about 5;
• (b) a third compound represented by one of Formulae 2-1 to 2-7 and having a dielectric constant equal to or greater about 5;
• and
• (c) a fourth compound represented by one of Formulae 3-1 to 3-3 and having a dielectric constant of less than about 5,
• wherein, at a temperature of 25° C.,
• the first compound has a viscosity of at most about 12 centipoise (cps) or is a solid,
• the second compound has a viscosity of at most about 70 cps,
• the third compound has a viscosity of at least about 80 cps or is a solid, and
• the fourth compound has a viscosity of at least about 20 cps or is a solid:
• wherein in Formulae 4-1 to 4-3,
• R20 to R23 are each independently of a substituted or unsubstituted C1 to C10 alkyl group, and
• L8 and L9 are each independently of a substituted or unsubstituted C1 to C20 alkylene group,
• wherein in Formulae 1-1 to 1-5,
• R1 to R3 and R6 are each independently a substituted or unsubstituted C1 to C20 alkyl group,
• R4 is a C1 to C20 alkyl group substituted by a hydroxyl group,
• R5 is a substituted or unsubstituted C2 to C20 alkyl group,
• L1 to L3 are each independently a substituted or unsubstituted C1 to C20 alkylene group, and
• n is an integer from 1 to 10,
• wherein in Formulae 2-1 to 2-7,
• R7, R8, and R11 to R16 are each independently a substituted or unsubstituted C1 to C20 alkyl group,
• R9 and R10 are each independently a C1 to C20 alkyl group substituted by a hydroxyl group, and
• L1, L2, and L4 are each independently a substituted or unsubstituted C1 to C20 alkylene group,
• and
• wherein in Formulae 3-1 to 3-3,
• R17 to R19 are each independently a substituted or unsubstituted C1 to C10 alkyl group, and
• L5 to L7 are each independently a substituted or unsubstituted C1 to C20 alkylene group.