Japanese scientists have developed a heterojunction germanium photo voltaic cell with the most important space ever achieved for the know-how. It has an open-circuit voltage of 291 mV, a short-circuit present of 45.0 mA/cm2, and a fill issue of 0.656.
Researchers from Tokyo Metropolis College have created a germanium (Ge) heterojunction photo voltaic cell with an space of 1 sq. centimeter, which they declare is the highest degree reported for the know-how up to now.
“The Ge heterojunction photo voltaic cell was developed as the underside cell of the triple-junction photo voltaic cell,” mentioned researcher Makoto Konagai. pv journal. “Concrete utilized analysis is a theme of the long run. It may be used as a detector within the infrared area or a light-emitting machine within the infrared area.”
One of many greatest points with Ge photo voltaic cells is cleansing the Ge wafers from impurities and lowering their reflectance.
“As a result of Ge wafers, in contrast to silicon, have nobody is aware of of a easy method to sculpt the feel to cut back the floor reflectance,” mentioned the scientists.
With this in thoughts, they constructed the cell with a magnesium fluoride (MgF2) as an anti-reflecting coating and the 80-nanometer indium tin oxide (ITO) substrate with antireflection properties. They mentioned that the 2 layers have been capable of enhance the cell short-circuit present.
The researchers additionally used an n-type based mostly passivation layer doped hydrogenated amorphous silicon (na-Si:H), a 317 mm thick p-doped Ge wafer that underwent hydrofluoric acid (HF) and hydrochloric acid (HCl) remedy, a buffer layer fabricated from a-Si:H, one other ITO substrate, and a silver (Ag) steel contact.
“In heterojunction Ge photo voltaic cells, the floor remedy of the wafers and the adjustment of the Si:H / p-Ge interface is essential,” they mentioned, noting that the HF and HCl therapies are the important thing to rising the open-circuit voltage. “Furthermore, neither rising the thickness of the ia-Si:H layer under resistivity substrate, the traits of the photo voltaic cell are taken care of to enhance all parameters. “
They examined the Ge photo voltaic cell underneath normal gentle circumstances. It achieves an effectivity of 8.6%, an open-circuit voltage of 291 mV, a short-circuit present of 45.0mA/cm2, and a fill issue of 0.656.
“Proper now, Ge wafers are costly, so we’re not on the stage of discussing value but,” Konagai mentioned. “Because the manufacturing value is excessive, you will need to enhance the conversion effectivity to cut back the price of energy technology.”
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