Transparent diffusive OLED substrate and method for producing such a substrate

A method for preparing a laminate substrate for a light emitting device, comprising:

• (a) providing a glass substrate having a refraction index, at 550 nm, of between 1.45 and 1.65,
• (b) coating a metal oxide layer onto one side of the glass substrate,
• (c) coating a glass frit having a refractive index, at 550 nm, of at least 1.7 onto said metal oxide layer, said glass frit comprising at least 30 weight % of Bi2O3,
• (d) firing the resulting coated glass substrate with the glass frit and the metal oxide layer at a temperature comprised between 530° C. and 620° C. thereby making react the metal oxide with the melting glass frit and forming a high index enamel layer with a plurality of spherical voids embedded in a lower section of the high index enamel layer near an interface with the glass substrate.