After photodiodes and –transistors and photo-resistors we may soon be using photo-capacitors too. Although “soon” may be a bit optimistic, Japanese researchers do claim that they have discovered a new phenomenon called the photo-dielectric effect. They even published a paper about it in Applied Physics Letters.

Using light to control the current conducting properties of materials is nothing new, and several techniques are known. Photo-conductance for instance uses light to change the electrical conductivity of a material, which in turn changes its dielectric permittivity. Such a material is close to being a photo-dielectric except that the change in conductivity would make for bad quality capacitors.

The newly-found effect does not influence the conductivity, but only the dielectric permittivity. The researchers used a ceramic with the composition LaAl0.99Zn0.01O3-d on which they shined light. When measuring its dielectric permittivity it was found to be dependent on the light’s intensity. The conduction of the ceramic, however, did not change. The mechanisms behind the observed effect are still unclear, but may have to do with defects in the material.

Source: Optical control of dielectric permittivity in LaAl0.99Zn0.01O3-d
Image: Public Domain