Researchers at the US National Renewable Energy Laboratory (NREL) and the University of Louisville have developed a revolutionary solar cell using tin oxide nanoparticles doped with yttrium. The innovation improves charge separation and overall cell performance.
“The cell lends itself to production, and there’s a startup out of Louisville — SoFab Inks — that’s doing just that,” researcher Thad Druffel said. pv magazine. “He was awarded $200,000 by the US Department of Energy in the Perovskite Solar Startup Challenge.”
The researchers said ETLs based on SnO2 offer low temperature solution processability, good photostability, high chemical stability, high electronic conductivity, good optical transparency, broadband hole, and favorable band alignment with perovskites.
“Furthermore, SnO2’s wide and tunable optical bandgap and deep conduction band (−4.3 eV) lead to optimal charge injection,” they said.
They synthesized yttrium-doped SnO2 nanoparticles to improve their electronic properties while maintaining the low-temperature annealing conditions needed to fabricate perovskite cells on substrates fabricated Polyethylene terephthalate (PET).
A cell has a pin architecture and active area 0.1 cm2. It is based on a flexible substrate made of PET and indium tin oxide (ITO), hole transport layer (HTL) made of polytriarylamine (PTAA), interface layer made of PFN polymer, perovskite absorber, yttrium doped material. Sno2 ETL, bathocuproin (BCP) buffer layer, and a silver (Ag) metal contact.
“PTAA, PFN, perovskite and SnO2 the layers were deposited with a single-step blade coating methods, while BCP and silver were deposited thermal evaporation,” the researchers said.
The team tested several cells under normal lighting conditions and found that they achieved a power conversion efficiency of 16.5%, an open-circuit voltage of 1.08V, and a short-circuit current of 22.40 mA/cm2and a fill factor of 68.4%. For comparison, a reference device with an ETL without yttrium doping achieved an efficiency of 14.3%, breakdown voltage 1.01 V, short-circuit current 22.40 mA/cm2and a fill factor of 63.3%.
The scientists attributed the cell’s increased performance to a new SnO2 ETL design.
“This material own minimal publishing, scalability, and manufacturing advantages over traditional organic ETLs that could improve competitiveness of commercial perovskite solar modules,” they concluded.
They introduced the device “Efficient inverted flexible perovskite solar cells by solution-phase coating of yttrium-doped SnO2 Directly in Perovskite”, published recently Applicable energy materials.