Electrochromic device and manufacturing method therefor

An electrochromic device comprising:

• a first electrochromic layer made of a first electrochromic derivative or a combination of a first electrochromic derivative and a first electrochromic agent;
• and
• a second electrochromic layer located on at least one surface of the first electrochromic layer and made of a second electrochromic derivative or a combination of a second electrochromic derivative and a second electrochromic agent,
• wherein the first electrochromic layer and the second electrochromic layer are in direct contact,
• wherein the diameter of the first electrochromic derivative and the diameter of the second electrochromic derivative satisfy the conditional expression 1 below:
• S1<S2 <Conditional Expression 1>
• where S1 is the diameter of the first electrochromic derivative, and S2 is the diameter of the second electrochromic derivative, and
• wherein the diameter of the first electrochromic derivative further satisfies the conditional expression 2 below:
• 1 nm<S1<500 nm. <Conditional Expression 2>