Droplet ejection head and printer

A droplet ejection head comprising:

• a nozzle plate having a nozzle configured to eject a liquid as droplets;
• a substrate having a pressure chamber continuous to the nozzle;
• a vibration plate forming a part of a wall surface of the pressure chamber;
• and
• a piezoelectric element containing potassium, sodium, and niobium and formed on the vibration plate, wherein
• the piezoelectric element includes a first electrode, a second electrode, and a piezoelectric layer located between the first electrode and the second electrode,
• a total thickness of the piezoelectric layer, the first electrode, and the second electrode is larger than a thickness of the vibration plate, and
• an absolute value of a displacement amount of the vibration plate when a voltage having an absolute value of 25 V is applied to the piezoelectric element as a voltage for displacing the vibration plate in a direction in which a volume of the pressure chamber expands is 2.0 times or more an absolute value of a displacement amount of the vibration plate when a voltage having an absolute value of 25 V is applied to the piezoelectric element as a voltage for displacing the vibration plate in a direction in which a volume of the pressure chamber contracts.