DAN OTVORENIH VRATA FIZIČKOG ODSJEKA
13. 4. 2018.
PMF - Fizički odsjek
Bijenička c. 32
HR-10 000 Zagreb
by one of the pioneers in the field of photonic crystals, Sajeev John.
Dept. of Physics, University of Toronto, Ontario, Canada
Photonic Crystals Solar Cells:
Prospects for World Record Efficiencies
Time: Ponedjeljak, 18. 6. 2018., 15:15 sati
Place: Fizički odsjek, prostorija F-201
Sajeev JohnPhotonic crystals are widely known for their light-trapping capabilities.
This is often associated with the occurrence of a photonic band gap or other suppression in the electromagnetic density of states [1,2]. This enables guiding of light on an optical micro-chip and unprecedented forms of strong-coupling between light and matter. In the past, practical applications of these effects have focused on information technology. More recently, an important opportunity has emerged in the area of energy technology. This arises from light-trapping in the higher bands of a photonic crystal, where the electromagnetic density of states is enhanced rather than suppressed. This enables unprecedented strong absorption of sunlight in a thin-film material with weak intrinsic absorption [3-10].
We describe designs of photonic crystal solar cells consisting of less than ten micron thickness of silicon that enable the absorption of 98% of all available sunlight in the wavelength range from 300 nm to 1100 nm. These 3D photonic crystals exhibit an enhanced electromagnetic density of states, consisting of slow group velocity modes, in which the flow of energy is transverse to the depth of a thin film of material. The ability to absorb nearly all sunlight, using light-trapping, in a flexible 10 micron sheet of silicon, enables considerable reduction of carrier Auger recombination losses in the bulk. Coupled with recent advances in surface passivation near electrical contacts, it is possible to reach a power conversion efficiency of 30%, well above the current world record for any silicon solar cell.