Flexible indoor perovskite solar cell achieves 32.5% efficiency


From pv magazine Global

Scientists at the University of Rome Tor Vergata have developed a perovskite solar cell for indoor applications such as autonomous wireless sensors, low-power consumer electronics, smart homes, domotics, and Internet of Things (IoT) applications.

“All these elements require efficient and easy-to-integrate energy harvesting devices to power them,” researcher Thomas M. Brown told pv magazine. “Indoor photovoltaic power sources, on ultra-thin bendable substrates, will have the potential to facilitate these technological innovations if they can provide sufficient energy under indoor illumination rather than the sun.”

The research team built the cell with a substrate made of polyethylene terephthalate (PET).

“Compared to other plastic substrates such as polyethylene naphthalate (PEN), PET offers greater UV durability and is six times more cost-effective,” Brown explained. “These qualities position it as the transparent polymer substrate of choice for plastic electronics.”

The researchers constructed the cell using a sequence of layers, including a PET substrate, an indium tin oxide (ITO) layer, a tin(IV) oxide (SnO2) electron transport layer (ETL), a perovskite absorber, a tetrabutylammonium bromide (TBAB) layer, a Spiro-OMeTAD hole-transporting layer (HTL), and a top electrode made of gold (Au).

The incorporation of TBAB atop the 3D perovskite matrix helped to reduce defect density and enhance the stability of the overall bulk 3D perovskite structure.

“This, in turn, reduces trap-assisted recombination which is critical for efficient carrier collection in indoor low-light conditions since the photogeneration rate of carriers is low,” the researchers said. “The overall result is a considerable enhancement in device performance.”

Tested under standard illumination conditions, the cell achieved a power conversion efficiency of 32.5%. It also maintained more than 80% of its initial efficiency after 1,000 bending cycles.

“The resulting PV cell has 1.4 times higher carrier lifetime, one order of magnitude lower leakage currents, and 3 times lower defect densities, suppressing recombination,” the group stated.

The researchers described the solar cell in “Highly Efficient Flexible Perovskite Solar Cells on Polyethylene Terephthalate Films via Dual Halide and Low-Dimensional Interface Engineering for Indoor Photovoltaics,” which was recently published in RRL Solar. The research team includes scientists from the University of Guilan in Iran, GreatCell Solar Italia, the Centre for Hybrid and Organic Solar Energy (CHOSE), the Institute of Crystallography (IC-CNR), the Institute of Nanotechnology (CNR NANOTEC), and the University of Salento.

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