Scientists from the University of North Carolina have developed a perovskite solar cell with an efficiency of 23.2% by adding benzylhydrazine hydrochloride (BHC) as an iodine (I) reductant agent in precursor solutions such as methylammonium iodide (MAI) and formamidinium iodide (FAI).
'Preventing the degradation of perovskite precursor solutions is equally important compared to post-fabrication device encapsulation, because large-area perovskite modules are generally manufactured in air and perovskite precursor inks are generally prepared in large quantity and stored for days or months,' the scientists said.
'In addition, the BHC residual in perovskite solid films can reduce the I2 generated during light soaking that induces the shallow charge traps and accelerates the decomposition of perovskite materials,' the scientists said.
Using this process, the researchers were able to fabricate an inverted blade-coated p-i-n perovskite cell with 23.2% efficiency, which was certified by the US Department of Energy's National Renewable Energy Laboratory (NREL). It also exhibited operational stability, with almost zero degradation after 1,000 hours of operation at maximum power point (MPP), using a perovskite composition that does not contain cesium. The cell also exhibited an open-circuit voltage of 1.17 V, a short circuit current of 24.0 mA cm2, and a fill factor of 0.829.
'All these results demonstrate the effectiveness of BHC in restoring precursor solutions and reducing film defects, accounting for the suppressed charge recombination and thus enhanced device efficiency,' the researchers said.
They then used the cells to produce perovskite mini-modules with an 18.5% efficiency level, as well as an open-circuit voltage of 11.7 V, a short-circuit current of 73.20 mA, and a fill factor of 0.773.
