Prominent Free Charges Tunneling Through Organic Interlayer of 2D Perovskites.

The diversity of organic cations greatly enriched the species of 2D perovskites; traditional 2D Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) perovskites are synthesized by two different organic amines. Here, according to the difference in pKa values between conjugated acids of monoprotonated and biprotonated 4-(2-Aminoethyl)pyridine (4AEPy) ions, we report the 2D perovskites of RP (4AEPy) 2 PbI 4 and DJ (4AEPy)PbI 4 from same organic amine, which can realize reversible transformation under the treatment of HI and NH 3 , respectively. The interaction of N-H···N hydrogen bond between adjacent organic molecules in (4AEPy) 2 PbI 4 leads to the bending conformation of ethylamine groups, which results in a 2.4 Å reduction in layer spacing compared to typical phenylethylamine lead iodine ((PEA) 2 PbI 4 ) 2D perovskite. Besides, the ethylamine groups of organic layers in (4AEPy)PbI 4 are deeply inserted into octahedral cavities and directly participate in the construction of the conduction band minimum, which leads to a small exciton binding energy of 27.3 meV. The stronger coupling between the organic and inorganic layers and the minor exciton binding energy can promote the DJ phase to possess a more stable structure and better optoelectronic properties. We further compared their optoelectronic performance of single crystal counterparts, and (4AEPy)PbI 4 device displays better light response and X-ray detection capability with a high sensitivity of 5627 μC Gy air -1 cm -2 and the lowest detectable dose rate of 20 nGy air s -1 . This article is protected by copyright. All rights reserved.