Some variations provide a photochromic heterostructure comprising: first semiconductor nanoparticles that have an average first-nanoparticle effective diameter from 1 nanometer to 20 nanometers, wherein the first semiconductor nanoparticles are not doped; and second semiconductor nanoparticles that have an average second-nanoparticle effective diameter from 1 nanometer to 60 nanometers, wherein the second semiconductor nanoparticles are doped with one or more transition metals, wherein the second semiconductor nanoparticles have a bandgap energy that is higher than the bandgap energy of the first semiconductor nanoparticles, and wherein the first semiconductor nanoparticles and the second semiconductor nanoparticles are in physical contact with each other. The disclosed photochromic heterostructure is especially useful when lower-energy light excites lower-energy-bandgap first nanoparticles to cause higher-energy-bandgap, doped second nanoparticles to photodarken. If the first nanoparticles were not present, the doped second nanoparticles would require higher-energy light to cause darkening. Examples demonstrate embodiments of the invention.

Devices and method for synchronized light and sound emission are disclosed. The device comprises: a first electrode layer; a second electrode layer; and a composite material layer disposed between the first electrode layer and the second electrode layer, the composite material layer having an electromechanical active matrix and an electroluminescent component; and wherein the electroluminescent component comprises a plurality of particle sets dispersed in the electromechanical active matrix, each particle set being continuous and having two ends each in contact with a respective one of the first and second electrode layers.

The present disclosure relates to an electro-opto-acoustic composition and an electro-opto-acoustic device, wherein, by adding a non-ionic surfactant, it is possible to improve a dielectric constant while simultaneously improving electroluminescence performance, and the electro-opto-acoustic composition according to an embodiment of the present disclosure includes a stretchable silicone rubber, a non-ionic surfactant, and copper-doped zinc sulfide (ZnS:Cu).