A team of researchers at the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) has succeeded in reaching new peak efficiencies for large-area, easy-to-fabricate silicon solar cells.
Using advanced cell structures, researchers have demonstrated that efficiencies of 20% are realistic in the near future, the institute says. Because more than 80% of solar cells manufactured today are based on crystalline silicon, the goal of the research is to further optimize the cost of silicon solar cells – the ‘workhorse’ of photovoltaics.
Currently, silicon solar cells convert an average of 14% to 19% of the incident solar energy into electricity. However, the transfer of recent research results into the production arena, concurrent with rapid market development in Germany, will help to continue to reduce the costs of photovoltaic electricity, Fraunhofer ISE predicts.
‘The investigated cell structures distinguish themselves in the type of silicon material – the so-called base – and in the type of emitter, a thin layer which collects the electrical charge carriers,’ explains Christian Schmiga, project leader for high-efficiency silicon solar cells at Fraunhofer ISE. ‘For processing the emitter layer, we used three different procedures as follows: aluminum alloying and boron diffusion for the p-emitter layer of our n-type solar cells and phosphorous diffusion for the n-emitter layer of our p-type solar cells.’
For an n-type silicon solar cell with an aluminum-alloyed emitter, the researchers reached a record efficiency of 19.3%. The researchers also achieved 19.6% efficiency for an n-type silicon solar cell featuring a boron-diffused emitter whose surface was passivated with an additional, new layer of aluminum-oxide.
SOURCE: Fraunhofer ISE