An ink comprising: - at least one particle comprising a first material and at least one liquid vehicle; wherein the particle comprises at least one particle comprising a second material and at least one nanoparticle dispersed in said second material; wherein the first material and the second material have an attenuation coefficient less or equal to 1×10 -2 cm -1 at 460 nm; wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets; or - at least one particle comprising a plurality of nanoparticles encapsulated in a material and at least one liquid vehicle; wherein said particle has a surface roughness less or equal to 5% of the largest dimension of said particle, wherein said surface roughness is the height difference between the highest peak and the deepest cavity on the surface of said particle, wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets; or - at least one particle comprising a first material and at least one liquid vehicle; wherein the particle comprises at least one particle comprising a second material and at least one nanoparticle dispersed in said second material; wherein said particle has a surface roughness less or equal to 5% of the largest dimension of said particle, wherein said surface roughness is the height difference between the highest peak and the deepest cavity on the surface of said particle; wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets. - at least one particle comprising a first material and at least one liquid vehicle; wherein the particle comprises at least one particle comprising a second material and at least one nanoparticle dispersed in said second material; wherein the first material and the second material have an attenuation coefficient less or equal to 1×10 -2 cm -1 at 460 nm; wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets; or wherein the particle comprises at least one particle comprising a second material and at least one nanoparticle dispersed in said second material; wherein the first material and the second material have an attenuation coefficient less or equal to 1×10 -2 cm -1 at 460 nm; wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets; or - at least one particle comprising a plurality of nanoparticles encapsulated in a material and at least one liquid vehicle; wherein said particle has a surface roughness less or equal to 5% of the largest dimension of said particle, wherein said surface roughness is the height difference between the highest peak and the deepest cavity on the surface of said particle, wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets; or wherein said particle has a surface roughness less or equal to 5% of the largest dimension of said particle, wherein said surface roughness is the height difference between the highest peak and the deepest cavity on the surface of said particle, wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets; or - at least one particle comprising a first material and at least one liquid vehicle; wherein the particle comprises at least one particle comprising a second material and at least one nanoparticle dispersed in said second material; wherein said particle has a surface roughness less or equal to 5% of the largest dimension of said particle, wherein said surface roughness is the height difference between the highest peak and the deepest cavity on the surface of said particle; wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets. wherein the particle comprises at least one particle comprising a second material and at least one nanoparticle dispersed in said second material; wherein said particle has a surface roughness less or equal to 5% of the largest dimension of said particle, wherein said surface roughness is the height difference between the highest peak and the deepest cavity on the surface of said particle; wherein the at least one nanoparticle is a luminescent nanoparticle and comprises at least 1% of semiconductor nanoplatelets.