Chinese researchers have constructed a hole transport layer with a mixed binary configuration combining Regioregular poly(3-hexylthiophene) (P3HT) and Spiro-OMeTAD polymer. They used it to build a perovskite solar cell that could retain 90% of its original efficiency after 1,200 hours of storage in a dark environment.
“These dopants have been reported to reduce device stability due to their hygroscopic nature and dopant-induced ion migration, which promotes perovskite degradation,” the researchers said.
They did HTL polymer Regioregular poly(3-hexylthiophene) (P3HT) and Spiro-OMeTAD in a mixed cabinet configuration, which they claim provides better protection for the perovskite absorber used in the cell due to the hydrophobicity of P3HT. “P3HT not only has a higher molecular order, but also has a preferred ‘face’ orientation, i.e. the P3HT molecules are parallel to the substrate, which has significant positive effects on the optoelectronic properties and charge carrier mobility,” they explained.
Chinese team built solar cell with indium tin oxide (ITO) substrate, tin(IV) oxide (SnO)2) electron transport layer (ETL), perovskite layer, proposed HTL, a molybdenum oxide (MoOx) buffer layer and a gold (Au) metal contact.
Academics tested the performance of several solar cells developed using this model, with an active surface area of 0.08 cm2 Through a solar simulator equipped with a 450 W Xenon lamp and a Keithley 2400 source meter under normal lighting conditions.
The power conversion efficiency of the master device was 24.30% and the certified efficiency was 24.22%. It also achieved an open circuit voltage of 1.18 V and a short circuit current density of 24.94 mA cm-2and a fill factor of 82.51%. The cell was also able to retain 90% of its original efficiency after 1,200 hours of storage in a dark environment.
“A successful modification of the conventional Spiro-OMeTAD HTL has been demonstrated by incorporating the hydrophobic polymeric P3HT into the Spiro-OMeTAD film to improve the efficiency and stability of perovskite solar cells,” the team concluded. “We believe this strategy paves the way for the development of low-cost, efficient and stable perovskite solar cells.”
The researchers presented their findings in the study “A Binary Hole Transport Layer Enables Stable Perovskite Solar Cells with PCE Exceeding 24%,” published recently DeCarbon.