Enhanced tin-based perovskite solar cells with acrylamide-doped hole-transport layer

The quality of the hole transport layer (HTL) is crucial for the overall efficiency of the perovskite solar cells. Although poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT:PSS) has been widely used as HTL for the perovskite solar cells, there is still room for further improvement of PEDOT:PSS by optimizing its energy level matching and the hole transfer efficiency. Based on the present issues of applying PEDOT:PSS as HTL in tin-based perovskite solar cells, the Lewis alkali acrylamide (AM), which contains both carbon-carbon double bond and the electrophilic amide group, is applied as the dopant in PEDOT:PSS solution. By analyzing the surface morphology and the crystal structure, it is revealed that AM can effectively improve both the quality and crystallinity of the formamidinium tin tri-iodide (FASnI 3 ) perovskite film, with the defects of the perovskite film greatly suppressed. The grain size of the modified FASnI 3 perovskite is observed to increase with the surface roughness reducing at the same time, along with the charge recombination resistance of the FASnI 3 perovskite film increasing. As a result, the modified devices have a higher short-circuit current, fill factor as well as power conversion efficiency. The characterization of the surface contact angle indicates that a more hydrophobic surface is formed as for the FASnI 3 perovskite film, which could efficiently retard the ambient vapor penetrating into the perovskite film.