Molecularly Engineered Organic-Inorganic Hybrid Perovskite with Multiple Quantum Well Structure for Multicolored Light-Emitting Diodes

Organic-inorganic hybrid perovskites have the potential to be used as a new class of emitters with tunable emission, high color purity and good ease of fabrication. Recent studies have so far been focused on three-dimensional (3D) perovskites, such as CH₃NH₃PbBr₃ and CH₃NH₃PbI₃ for green and infrared emission. Here, we explore a new series of hybrid perovskite emitters with a general formula of (C₄H₉NH₃)₂(CH₃NH₃)_n-1Pb_nI_3n+1(where n = 1, 2, 3), which possesses a multiple quantum well structure. The quantum well thickness of these materials is adjustable through simple molecular engineering which results in a continuously tunable bandgap and emission spectra. Deep saturated red emission was obtained with a peak external quantum efficiency of 2.29% and a maximum luminance of 214 cd/m 2. Green and blue LEDs were also demonstrated through halogen substitutions in these hybrid perovskites. We expect these results to open up the way towards high performance perovskite LEDs through molecular-structure engineering of these perovskite emitters.