Glass microparticles improved solar batteries
The scientists have worked on the increase of efficiency of solar batteries composed of a thin film of amorphous silicon. The small thickness is both an advantage and a disadvantage of such battery. As a general rule, one needs a layer of amorphous silicon of only several micrometers whereas plates of crystalline silicon are not thicker than 180 micrometers.
However, the lower material consumption is often canceled out by the issue that a photon can easier penetrate through such a thin layer of material and either absorbed by the support causing an unfavorable heat of the solar cell or even reflected outwardly. Both scenarios decrease a coefficient of efficiency of the device.
To collect the current from the photocell, the researchers have applied a thin electrode composed of zinc/aluminum oxide. The electrode has been fabricated by the atomic-layer deposition. Additionally, glass microspheres of a diameter slightly less than a micron have been embedded in the electrode. Each microsphere has a globule shape. Because photons reflecting from microspheres in most cases could not «get out» of the solar battery, the efficiency of the device has increased. Additionally, the deleterious heat of the photocell support caused by the incomplete absorption of photons of solar light by the upper layer of the battery has been mitigated.
The overall coefficient of efficiency of the photocell made of amorphous silicon has increased by 20 percent if compared to the non-upgraded device. The researchers note that the new electrode due to its small thickness, transparency, and capability to increase the level of absorption of photons of the solar cell, can be applied not only of amorphous silicon but also for photocells composed of materials from other classes. All applied compounds (zinc oxide, silicates) are cheap especially if compared to the typical electrodes for solar batteries present nowadays at the market which are often based on silver.
The article with the new development is published in Optic Letters.
Previously, the scientists have managed to create a solar battery without an accumulator.