To provide a visible light-emitting diode produced from a soluble semiconductive polymer.

The method of producing a light-emitting diode that emits visible light, and tuned on at 5V or a lower voltage, the method comprises (i) a step of precoating a substrate, using a conductive transparent first layer that has a high work function, and acts as a hole discharge electrode; (ii) a step of directly casting a transparent layer comprising a soluble semiconductive light-emitting conjugated polymer on the first layer from a solution; (iii) a step of forming an electron emitting contact on the semiconductive conjugated polymer layer from a metal having a low work function, wherein the metal having a low work function is calcium.