Abstract
Wide bandgap perovskite solar cells have gained extensive attention due to their complementary absorption to fabricate high performance tandem solar cells with low bandgap absorbers,whereas the open-circuit voltage(V_(OC))loss caused by halide segregation and defects is one of the main issues hindering their performance.Herein,we report a strategy of adding organic bromide salts with different chain lengths including phenylammonium bromide(PhABr),phenmethylammonium bromide(PMABr)and phenethylammonium bromide(PEABr)into perovskite precursor to suppress the formation of iodide-rich phases and passivate the defects in perovskite films.It is shown that PMABr,which possesses moderate chain length,performs best in improving device performance.The power conversion efficiency(PCE)of 17.32% with enhanced V_(OC)have been achieved,which are much better than these of the standard device(15.72%)and the devices with PhABr(15.98%)or PEABr additives(16.83%).As the chain length is a common variable among different additives,so the results obtained in this work show that it shall be considered in screening the additives.
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