Light-Emitting Device

A light-emitting device comprising:

• a first electrode over an insulating surface;
• a second electrode facing the first electrode;
• and
• an EL layer between the first electrode and the second electrode,
• wherein the EL layer comprises a light-emitting layer, a hole-transport layer, a first electron-transport layer, and a second electron-transport layer,
• wherein the first electron-transport layer is between the light-emitting layer and the second electron-transport layer,
• wherein the second electron-transport layer is between the first electron-transport layer and the second electrode,
• wherein the light-emitting layer is between the hole-transport layer and the first electron-transport layer,
• wherein the first electron-transport layer comprises a first organic compound,
• wherein the second electron-transport layer comprises a second organic compound,
• wherein the first organic compound and the second organic compound each independently comprise a π-electron deficient heteroaromatic ring,
• wherein a GSP_Slope (mV/nm) of an evaporated film of the second organic compound is larger than a GSP_Slope (mV/nm) of an evaporated film of the first organic compound, and
• wherein the GSP_Slope (mV/nm) is represented by ΔV/Δd where ΔV (mV) is an amount of change in surface potential and Δd (nm) is an amount of change in thickness.