| Work Detail |
Chinese scientists built the device by depositing multiple metal nanofilms on both sides using plasma-enhanced chemical vapor deposition. The cell achieved an open circuit voltage of 684 mV, a short circuit current density of 38.2 mA/cm2 and a fill factor of 80.8%.
Researchers at Chinas Hangzhou Dianzi University have made a thin-film p-type monocrystalline solar cell that they claim can achieve power conversion efficiency close to that of their thick industrial counterparts.
“Overall, the results of this study present a novel way to make high-performance thin crystalline silicon solar cells using much less silicon: for a 20 µm cell, about one-eighth the amount needed for a thick 20 µm cell. 160 µm in a given panel size,” says researcher Leonidas Palilis.
In the article “ Investigation on significant efficiency enhancement of thin crystalline silicon solar cells ,” published in the Journal of Photonics for Energy (JPE) , the scientists explain who used the layer transfer (LT) method instead of cutting silicon ingots for the production of the wafer used for the cell. LT is a technique for transferring a layer of a semiconductor material, often wafer-sized, from the original substrate to the target substrate.
With this method, hydrofluoric acid (HF) is first used electrochemically to etch pores in a thick silicon wafer for porous silicon and this wafer is used as a substrate to epitaxially grow a layer of single-crystalline silicon. The thin layer of epitaxial silicon is then peeled off the porous silicon substrate.
Through this process, the scientists obtained a thin 20µm thick p-type monocrystalline silicon wafer. They then deposited multiple passivation layers of aluminum oxide (Al2O3), silicon nitride (NiO2), and silicon monoxide (SiOx) using plasma-enhanced chemical vapor deposition (PECVD) on the front of the cell.
These contacts have two different configurations – SiO2/SiNx/SiOx and Al2O3/SiNx/SiOx – and reportedly improve light absorption at short wavelengths and longer wavelengths, which in turn improves the short circuit current and open circuit voltage of the cell.
“Compared to a standard solar cell used as a reference, the current density increased from 34.3 mA/cm2 to 38.2 mA/cm2,” say the academics, adding that the passivation layers also contributed to raising the voltage. cell open circuit from 632 mV to 684 mV.
As a result, the device fill factor increased from 76.2% to 80.8% and the cell efficiency grew from 16.5% to 21.1%.
“This advancement will likely contribute to more widespread and cost-effective adoption of silicon solar energy technology, due to the reduction in cost and concomitant expansion of solar panel manufacturing capacity,” Palilis said. |
