Researchers at South Korea’s Ulsan National Institute of Science and Technology (UNIST), Chonnam National University and Pohang University of Science and Technology (POSTECH) have developed a unique perovskite solar cell that uses alkylammonium chloride (RACI) to control the formation of defects in the perovskite layer.
The US National Renewable Energy Laboratory (NREL) has certified the South Korean research team's cell's 25.73% efficiency. The champion device built by the scientists reached an efficiency of 26.08%.
“Alkylammonium chloride, which is dequantized at the crystallization stage while combining with perovskite components, was used,” said researcher Sang Il Seok. “This optimal combination with Alkyl was also able to optimally control the rate of volatilization with solvent during coating and heat treatment of perovskite precursor solution.”
The team built the cell with formamidinium lead iodide (FAPbI3) metal halide perovskite, which offers superior thermal stability and a narrow bandgap. The new process enables the creation of a dense perovskite film with good crystallinity, they claimed. They investigated the surface morphology of the film via grazing incident wide-angle X-ray diffraction and scanning electron microscopy.
“RACl added to the precursor solution was believed to be easily volatilized during coating and annealing,” the scientists explained.
The film was tested in a perovskite cell and found that it achieved a power conversion efficiency of 26.08%, an open-circuit voltage of 1.18 V, a short-circuit current of 25.7 mA/cm2, and a fill factor of 86.15%. When tested by NREL experts, the device achieved a certified efficiency of 25.73%.
“This study is very meaningful, as it examines the crystallization process of perovskite with halide anions in real time through the UNIST-PAL Beamline of Pohang Accelerator Laboratory,” said researcher Tae Joo Shin from UNIST.
