Nano-structured photovoltaics
The intermediate energy bands are established within the forbidden gap of a semiconductor material with the incorporation of a superlattice nanostructure of another semiconductor material. These bands allow the absorption of low-energy photons in addition to the usual higher-energy photons. Researchers working on the project CHALQD (Chalcopyrite quantum dots for intermediate band solar cells) combined the excellent light-absorbing properties of chalcopyrite-type semiconductors with the quantum properties of nano-structured materials. Specifically, the researchers made a significant step in the preparation of chalcopyrite (Cu(In, Ga)Se2) quantum dots using molecular beam epitaxy to evaporate copper (Cu), indium (In) and selenium (SeThe growth of chalcopyrite quantum dots was performed sucessfully on both crystalline and non-crystalline substrates. The researchers also performed work towards devices by analysing high-bandgap dielectric materials to be used in this type of solar cell as passivation layers. Electron-beam lithography was used to pattern nano-structures that were used as point contacts in the rear electrode of a thin film solar cell. This innovative solution proposed was filed as a patent application. CHALQD results have paved the way to the future manufacturing of highly efficient intermediate-band solar cells that could lower the cost of solar electricity and become an important branch of the photovoltaic industry.
Keywords
Photovoltaics, power conversion, solar cells, nanostructures, intermediate-band, semiconductor