A substrate (100,200) for an organic electronic device comprising: a base layer; a particle-containing layer which is present on the base layer and which includes: first light-scattering particles having an average particle diameter of 100 nm or more, second particles having an average particle diameter of 30 to 500 nm, the average particle diameter of the second particles being smaller than that of the first light-scattering particles, and a binder having a refractive index of 1.5 or more, an overcoat layer which is formed on the particle-containing layer, and which has a refractive index of 1.5 to 3.5, wherein the overcoat layer includes particles having a refractive index of 1.5 or more, and an average particle diameter of 1 to 100 nm; and an electrode layer formed on the particle-containing layer; wherein refractive indices are 2. measured with respect to light with a wavelength of 550 nm; characterised in that: (i) the refractive index of the second particles is smaller than that of the first light-scattering particles, (ii) the first light-scattering particles have a difference in refractive index from the binder of more than 0.4, (iii) the second particles have a difference in refractive index from the binder of 0.15 or less, 11 (iv) the particle-containing layer is sealed by the electrode layer and the base layer. a base layer; a particle-containing layer which is present on the base layer and which includes: first light-scattering particles having an average particle diameter of 100 nm or more, second particles having an average particle diameter of 30 to 500 nm, the average particle diameter of the second particles being smaller than that of the first light-scattering particles, and a binder having a refractive index of 1.5 or more, first light-scattering particles having an average particle diameter of 100 nm or more, second particles having an average particle diameter of 30 to 500 nm, the average particle diameter of the second particles being smaller than that of the first light-scattering particles, and a binder having a refractive index of 1.5 or more, an overcoat layer which is formed on the particle-containing layer, and which has a refractive index of 1.5 to 3.5, wherein the overcoat layer includes particles having a refractive index of 1.5 or more, and an average particle diameter of 1 to 100 nm; and an electrode layer formed on the particle-containing layer; wherein refractive indices are 2. measured with respect to light with a wavelength of 550 nm; characterised in that: (i) the refractive index of the second particles is smaller than that of the first light-scattering particles, (ii) the first light-scattering particles have a difference in refractive index from the binder of more than 0.4, (iii) the second particles have a difference in refractive index from the binder of 0.15 or less, 11 (iv) the particle-containing layer is sealed by the electrode layer and the base layer. (i) the refractive index of the second particles is smaller than that of the first light-scattering particles, (ii) the first light-scattering particles have a difference in refractive index from the binder of more than 0.4, (iii) the second particles have a difference in refractive index from the binder of 0.15 or less, 11 (iv) the particle-containing layer is sealed by the electrode layer and the base layer.