Researchers show that introducing rough interfaces on the solar panel surface can increase their efficiency significantly.
Most commercial solar panels are silicon based, but there are more highly efficient solar panels which may replace silicon solar cells one day. These solar cells are perovskite solar cells. Perovskites are materials with a crystal structure similar to that of the naturally-occurring mineral perovskite. Due to their high efficiency, perovskite has been focused greatly for the development of next-generation solar energy technologies.
The efficiency of any photovoltaic module depends on the surface and its reflectivity. Researchers have shown that introducing tiny nanoscale texturing on the surfaces of materials in perovskite/silicon tandem solar cells can significantly increase efficiency by reducing the amount of light energy that is lost due to reflection. The newly developed design has the potential to achieve power conversion efficiency of more than 29%. Simulations suggest that this efficiency can be further improved with better fabrication techniques and additional texturing.
Philipp Tockhorn from Helmholtz-Zentrum Berlin (HZB) will present the work at the virtual OSA Advanced Photonics Congress on 29th July.
“We present nanotextured perovskite/silicon tandem solar cells that are on par with the best cells presented in this highly dynamic field,” said Tockhorn. Our findings may contribute to the further development of highly efficient perovskite/silicon tandem solar cells and have the potential to further decrease the cost of solar electricity.”
The researchers, through simulations,  first calculated the electric current in the perovskite and silicon subcells when the perovskite layer was flat, and nanostructured bumps only on the bottom. The simulated bumps were about 300 nm high and 750 nm apart. They found out that the fully textured perovskite layer was able to absorb considerably more light, increasing the photocurrent density by 0.7 mA/cm2 per subcell. They moreover discovered that the one-sided nanotexturing already increased the light absorbed and current generated in the silicon absorber layer by 0.2-0.3 mA/cm².
“Remarkably, the nanotextures not only improve the light absorption but also lead to a slight enhancement of the tandem solar cell’s electronic quality in comparison to the planar reference in conjunction to better film processing conditions,” Tockhorn said.