Enhancing and Extinguishing the Different Emission Features of 2D (EA_(1?x)FA_x)_4Pb_3Br_(10) Perovskite Films

摘要

2D hybrid perovskites are attractive for optoelectronic devices. In thin films,the color of optical emission and the texture of crystalline domains are oftendifficult to control. Here, a method for extinguishing or enhancing differentemission features is demonstrated for the family of 2D Ruddlesden–Popperperovskites (EA_(1?x)FA_x)_4Pb_3Br_(10) (EA = ethylammonium, FA = formamidinium).When grown from aqueous hydrobromic acid, crystals of (EA_(1?x)FA_x)_4Pb_3Br_(10)retain all the emission features of their parent compound, (EA)4Pb3Br10. Surprisingly,when grown from dimethylformamide (DMF), an emission feature, likelyself-trapped exciton (STE), near 2.7 eV is missing. Extinction of this featureis correlated with DMF being incorporated between the 2D Pb-Br sheets,forming (EA_(1?x)FA_x)_4Pb_3Br_(10)?(DMF)_y. Without FA, films grown from DMF form(EA)4Pb3Br10, retain little solvent, and have strong emission near 2.7 eV. Slowingthe kinetics of film growth strengthens a different emission feature, likely adifferent type of STE, which is much broader and present in all compositions.Films of (EA_(1?x)FA_x)_4Pb_3Br_(10)?(DMF)_y have large, micron-sized domains andhomogeneous orientation of the semiconducting sheets, resulting in low electronicdisorder near the absorption edge. The ability to selectively strengthenor extinguish different emission features in films of (EA_(1?x)FA_x)_4Pb_3Br_(10)?(DMF)_yreveals a pathway to tune the emission color in these compounds.