Iraqi researchers have incorporated an electron transport layer (ETL) made of tin(IV) oxide into a perovskite solar cell using air thermal annealing, improving efficiency and stability. The breakdown voltage of the device was 1.045 V, the short circuit current was 22.01 mA/cm2 and the fill factor was 74.3%.
The researchers said, “Moderate temperature deposition of RF magnetron sputtered SnO2-based electron-transporting layer for ternary cationic perovskite solar cells,” which perovskite solar devices often use titanium oxide (TiO2 i) as the primary agent in the light-induced degradation observed in perovskite solar cells.
“Unlike TiO2 material, SnO2 can be processed at much lower temperatures using a variety of deposition techniques, including solution processes, electroplating, electron beam, atomic layer deposition, and magnetron sputtering,” the researchers said. “Among all these thin fabrication methods, magnetron sputtering (MS) is one of the most promising technologies due to its advantages of cost-effectiveness and to uniform large-scale SnO.2 thin films.”
The research team sprayed SnO2 material through high-energy argon plasma ions onto a substrate made of fluorine-doped tin oxide (FTO) and glass. The cell also uses an absorber made of a perovskite material known as Cs0.05Mon0.10FA0.85Pb(I0.85Bro0.15)3A hole transport layer (HTL) made of Spiro-OMeTAD and a gold-based top electrode (Au).
Scientists said that SnO2 the thin film showed high crystalline quality because it contains more oxygen due to the air-heat annealing treatment.
“SnO2 the films have shown quite high optical transmittance in the visible range of more than 80 percent,” they said. “The thermal annealing process has clearly improved the electrical conductivity by significantly increasing the electron mobility, and this observation corresponds to the increase in crystallite size after the annealing process.”
They compared the performance of the device with a reference cell with a SnO-based ETL2 is deposited without a thermal annealing process. The latter achieved a power conversion efficiency of 15.07% and the former 17.1%. The new cell also achieved a breakdown voltage of 1.045 V, a short-circuit current of 22.01 mA/cm2, and a duty cycle of 74.3%, with an average lifetime of more than 200 hours.
“Sputtered SnO2 as ETL was shown to enable good PV device performance, stability and lifetime, and could serve as a promising route for the further development and integration of sputtered SnO2 films for large-scale and cost-effective perovskite PV modules,” the research team concluded.