Spiro-OMeTAD doped with iodine pentoxide to enhance planar perovskite solar cell performance

Due to its enormous development potential, research on perovskite solar cells (PSCs) is progressing rapidly worldwide. Among numerous hole transport materials (HTMs), an organic molecule spiro-OMeTAD emerged victorious. Spiro's application in PSCs is constrained to its weak hole mobility and low conductivity. Here, an inexpensive, ecologically friendly inorganic oxidant iodine pentoxide (I2O5) is used to aid in quick and manageable oxidation of Spiro. I2O5-modified Spiro as HTM improves the charge carrier transportation. Meanwhile, trap-states density and trap-assisted recombination are decreased. Additionally, the modification adjusts the HTM's energy level to match the perovskite layer properly. As a result, the I2O5-modified PSC achieves a champion power conversion efficiency of 22.80%, while the pristine device gets an efficiency of 20.65%.