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Chinese researchers have built a perovskite tandem solar cell with a superior perovskite device based on an n-butanol-treated absorber, which appears to reduce the detrimental effects of humidity in manufacturing processes carried out in air. The result is a tandem cell with better charge uptake.
A group of researchers led by Nanjing University in China has designed a perovskite-silicon tandem solar cell with a new solvent engineering strategy that uses n-butanol (nBA), also called normal butyl alcohol, which is a clear, colorless primary alcohol used as a cleaning agent in many industries, including electronics manufacturing.
The scientists explained that nBA offers low polarity and saturation vapor pressure and ensures that the typical detrimental effects of humidity in the fabrication of perovskite cells in an ambient environment can be significantly reduced.
The perovskite film on the top device of the tandem cell had an active surface area of ??0.049 cm2 and was manufactured using co-evaporation and knife coating techniques, which the research group says meets the requirements for the fabrication of perovskite films. large surface area.
“It should be noted that the second step was carried out in air to conform to a realistic production environment,” explains the group, noting that nBa replaced the usual ethanol and isopropyl alcohol, which negatively affect the uniformity of the film . “Both the polarity and the evaporation rate of the solvent have a joint effect on the absorption levels of H2O. From this point of view, nBa emerges as the optimal solvent for our specific requirements.”
The nBa-based film was found to exhibit better charge pickup, because larger grain sizes minimized recombination, compared to control films grown with conventional solvents.
The researchers constructed the top cell with a glass-coated indium tin oxide (ITO) absorber, a nickel(II) oxide (NiO) layer, a hole transport layer (HTL) with a self-assembled monolayer (SAM). ), a perovskite absorber with an energetic bandgap of 1.68 eV, an electron transport layer based on buckminsterfullerene (C60) and a tin oxide (SnOx) buffer layer, and a copper (Cu) electrode.
Tested under standard lighting conditions, this device achieved a power conversion efficiency of 20.8%.
The top device was then integrated into a tandem cell with an active area of ??1,044 cm2 that integrated a bottom heterojunction silicon solar cell. This cell achieved an efficiency of 29.4%, an open circuit voltage of 1.83 V, a short circuit current density of 20.45 mA cm-2 and a fill factor of 78.63%.
The team was also able to certify an efficiency of 28.7% for the tandem cell and 26.3% for a device with an aperture area of ??16 cm2. “The encapsulated device retained 96.8% of the initial production after 780 h of monitoring the maximum power point,” the academics add. “In addition, we have demonstrated the potential for commercial scale-up by achieving a 25.9% conversion efficiency for 16 cm² devices manufactured by slot coating.”
They presented the cell in the article “ Solvent engineering for scalable fabrication of perovskite/silicon tandem solar cells in air ,” published in Nature Communications . “This solvent engineering strategy demonstrates the viability of commercial perovskite-silicon tandem solar cells,” they conclude. |
