Italian scientists have used a titanium oxide sponge to successfully prevent lead leakage in a semitransparent solar cell. The device has demonstrated comparable efficiency to semi-transparent perovskite devices and has an average visible transmittance (AVT) of 31.4%.
Scientists from the Italian Institute for Microelectronics and Microsystems (CNR-IMM) have developed a semi-transparent perovskite solar cell. They achieved this by depositing a titanium oxide (TiO2) sponge on the device to prevent potential lead (Pb) leakage.
“We conceived the solar cell for applications in building-integrated photovoltaics (BIPV) and agrivoltaics, where the potential lead leakage can be viewed as a serious public environmental and health risk source,” researcher Salvatore Valastro told pv magazine.
TiO2, a highly adsorbent material, serves as an effective electron transport layer (ETL) in perovskite solar cells. To address potential lead (Pb) leakage, the researchers created a solvent-free porous TiO2 film, forming a sponge-like structure capable of capturing Pb from damaged cells during simulated catastrophic events.
“The TiO2 sponge can sequester Pb in concentrations ranging from 24 g cm2 to 63 g cm2, which are equivalently contained in MAPbI3 layers with thicknesses from 200 nm (semi-transparent PSC) to 500 nm (opaque PSC),” the researchers explained.
They built the cell with a substrate made of glass and indium tin oxide (ITO), a hole transport layer (HTL) made of poly-triarylamine (PTAA), a perovskite absorber with the TIO2 sponge, an electron acceptor made of phenyl-C61-butyric acid methyl ester (PCBM), a bathocuproine (BCP) buffer layer, a gold (Au) metal contact, and the TIO2 sponge.
“We deposited the sponge via a physical solvent-free deposition, by using sputtering equipment, an easily up-scalable deposition method, which is widely used by semiconductors manufacturing companies,” Valastro said. “A pre-sputtering step of 1 min is performed before the deposition process to clean up the surface of the titanium target to remove oxidized layers.”
The solar cell achieved a power conversion efficiency of 11.6% and has an average visible transmittance (AVT) of 31.4%. “The efficiency value of 11.6% is characteristic of this semi-transparent architecture,” said Valastro.
The research team described the cell tech in “Preventing lead leakage in perovskite solar cells with a sustainable titanium dioxide sponge,” which was recently published in Nature Sustainability.
“Our method represents a concrete step forward in addressing Pb release for BIPV, BAPV, agrivoltaics and opaque devices, and also paves the way for Pb recycling in end-of-life devices,” the team concluded.
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