Optical stack structure, manufacturing method therefor, and smart window comprising same

A variable transmittance optical stack comprising:

• a first stack in which a first polarizing plate comprising a first functional coating layer, a first transparent conductive layer, and a first alignment film are stacked in order;
• a second stack opposed to the first stack, and in which a second polarizing plate comprising a second functional coating layer, a second transparent conductive layer, and a second alignment film are stacked in order;
• and
• a liquid crystal layer disposed between the first stack and the second stack,
• wherein the liquid crystal layer comprises a ball spacer provided via an adhesion-imparting layer formed on at least one of the first alignment film and the second alignment film,
• the ball spacer has a diameter ranging from 4 to 10 μm,
• at least one of the first transparent conductive layer and the second transparent conductive layer is formed in direct contact with one of the first polarizing plate and the second polarizing plate,
• each of the first functional coating layer and the second functional coating layer has Vickers hardness ranging from 18 to 41, and
• the number of ball spacers (A) per unit area (1 mm2) with respect to a diameter (d;
• μm) of each ball spacer satisfies following equation 1.
• -
• 1
• .
• 3
• ⁢
• 3
• ⁢
• 3
• ⁢
• 3
• ⁢
• d
• 3
• +
• 3
• ⁢
• 2
• .
• 3
• ⁢
• 2
• ⁢
• 1
• ⁢
• d
• 2
• -
• 2
• ⁢
• 6
• ⁢
• 5
• .
• 2
• ⁢
• d
• +
• 8
• ⁢
• 0
• ⁢
• 2
• .
• 1
• ⁢
• 4
• ≤
• A
• ≤
• -
• 17.
• ⁢
• 6
• ⁢
• 3
• ⁢
• 9
• ⁢
• d
• 3
• +
• 4
• ⁢
• 2
• ⁢
• 7
• .
• 2
• ⁢
• 6
• ⁢
• d
• 2
• -
• 3
• ⁢
• 5
• ⁢
• 0
• ⁢
• 2
• .
• 2
• ⁢
• d
• +
• 1
• ⁢
• 0
• ⁢
• 7
• ⁢
• 3
• ⁢
• 6
• [
• Equation
• ⁢
• 1
• ]