Ruddlesden–Popper and Dion–Jacobson Perovskites in Multiple Quantum Wells Light‐Emitting Diodes

Abstract Low dimensional perovskite forms multiple quantum wells (MQWs) structures that can be an efficient structure for light‐emitting diodes (LEDs). Here the use of different barrier molecules is demonstrated to create Ruddlesden–Popper and Dion–Jacobson 2D perovskite and implement them in LEDs. It is found that the aromatic barrier molecules are better performing in Perovskite LED (PeLED) compared to linear barrier molecules. The benzylammonium (BnzA), n = 5, shows the highest external quantum efficiency (EQE) of 16.65% compared to the di‐ammonium and the linear barrier molecules. The BnzA forms n = 1 inside the 3D perovskite, which provides a non‐radiative energy transfer from the wider bandgap, n = 1 perovskite, to the smaller bandgap, 3D perovskite, that presents radiative recombination. Optical characterizations support the MQW structure whereas physical characterizations show unique morphology of separate nanocrystals laying on top of thin perovskite film during the n = 5 BnzA crystallization. In addition, it is revealed that the barrier molecule type, in this case, the BnzA, is responsible for the formation of the MQW structure whereas other barrier molecules didn't show this structure. The formation of an additional low n‐value phase inside the 3D perovskite is beneficial for the enhancement of the radiative recombination which results in high EQE.