Article including two external layers of absorbing nanoparticles

An article comprising:

• two external absorbing layers of absorbing nanoparticles, the external absorbing layers being the outermost deposited layers of the article;
• and
• at least one refractive index layer chosen from a high refractive index layer (H) and a low refractive index layer (L), wherein the at least one refractive index layer is between the two external absorbing layers of absorbing nanoparticles,
• wherein the at least one refractive index layer includes a carrier and at least one nanoparticle chosen from organic nanoparticles and inorganic nanoparticles,
• wherein the high refractive index layer comprises a high refractive index material with a first index of refraction, and the low refractive index layer comprises a low refractive index material having a second index of refraction, the first index of refraction being greater than 1.65 and the second index of refraction being less than 1.65, and
• wherein the article has one of the following layering structures:
• (i) external absorbing/H or L with a specific quarter waves optical thickness (QWOT)/external absorbing;
• (ii) external absorbing/stack/external absorbing;
• (iii) external absorbing/H or L/absorbing/H or L/external absorbing;
• or
• (iv) external absorbing/stack/absorbing/stack/external absorbing,
• wherein absorbing refers to a layer of absorbing nanoparticles, and stack refers to a stack of alternating layers of low refractive index layers and high refractive index layers and
• wherein in the layering structures, adjacent layers separated by a backslash (“/”) are in direct physical contact.