US 12,754,443 B1 · Rapidly reversible and wavelength-tunable photochromic compositions, systems, and methods

Abstract

Rapidly reversible and wavelength-tunable photochromic compositions and systems are disclosed. Nanoparticles photochromically darken in response to incident light by photo-oxidizing a dopant to reversibly create an optically absorbing mid-gap electronic state. The wavelengths that trigger photochromic darkening as well as the absorbed wavelengths may be tuned by changing the nanoparticle composition, the nanoparticle size, and/or the dopant. The time for reversal of darkening may be tuned using hole-accepting ligands attached to the nanoparticles as well as hole-accepting molecules adjacent to the nanoparticles. Some variations provide a photochromic composition comprising: semiconductor nanoparticles; transition-metal dopant particles; and organic ligands bonded to the semiconductor nanoparticles, wherein the organic ligands contain at least one unsaturated carbon bond and are capable of accepting transfer of a photoexcited hole from the dopant particles and/or the semiconductor nanoparticles. In the disclosed systems, there is an on/off switch for the photochromic function. Many photochromic uses are described.

Claims18

Dependent claims

A photochromic composition comprising:

(a) semiconductor nanoparticles that have an average nanoparticle effective diameter from about 1 nanometer to about 20 nanometers;
(b) transition-metal dopant particles disposed on surfaces of said semiconductor nanoparticles and/or within said semiconductor nanoparticles, wherein said transition-metal dopant particles are capable of undergoing reversible oxidation and reduction;
and
(c) organic ligands bonded to said semiconductor nanoparticles, wherein said organic ligands each contain at least one carbon-carbon aromatic bond, at least one carbon-carbon double bond, or at least one carbon-carbon triple bond, wherein said organic ligands are capable of accepting transfer of a photoexcited hole from said transition-metal dopant particles and/or said semiconductor nanoparticles, and wherein, on average, there are 8 or less carbon atoms between a bond site and the first carbon atom with an aromatic bond, a double bond, or a triple bond in the direction away from said bond site, wherein said bond site is the site at which one of said organic ligands bonds to one of said semiconductor nanoparticles.

1 more element

Dependencies are inferred from the claim text.

Rapidly reversible and wavelength-tunable photochromic compositions, systems, and methods

Life of this patent

Rapidly reversible and wavelength-tunable photochromic compositions, systems, and methods

Life of this patent

Abstract

Claims18