This invention relates to the field of
perovskite solar cells, specifically a method for preparing high-purity
formamidinium hydroiodate, comprising the following steps: dissolving
formamidinium acetate in
hydroiodic acid solution and stirring to obtain a precursor solution of
formamidinium hydroiodate; heating the solution in an
oil bath to obtain a crude product of formamidinium hydroiodate; cooling the product and adding an
ethanol solution, then heating again until completely dissolved to obtain a hot saturated solution; removing the hot solution and vacuum filtering, and pouring the resulting
mother liquor into a crystallizing dish for
crystallization; after
crystallization, adding
diethyl ether for washing; placing the washed flaky crystals in an
oil bath and adding
ethanol again for heating to dissolve, then filtering, and pouring the resulting
mother liquor back into a crystallizing dish for low-temperature
crystallization; repeating the above steps three times; and
vacuum drying the obtained product to obtain formamidinium hydroiodate, which is the target product. The formamidinium hydroiodate of this invention, when applied to a
perovskite layer, can greatly improve the photovoltaic performance of
perovskite solar cells and significantly improve the stability of the device.