Abstract
The studies of quantum interference effects through bulk perovskite materials at the Ångstrom scale still remain as a major challenge. Herein, we provide the observation of room-temperature quantum interference effects in metal halide perovskite quantum dots (QDs) using the mechanically controllable break junction technique. Single-QD conductance measurements reveal that there are multiple conductance peaks for the CH3NH3PbBr3 and CH3NH3PbBr2.15Cl0.85 QDs, whose displacement distributions match the lattice constant of QDs, suggesting that the gold electrodes slide through different lattice sites of the QD via Au-halogen coupling. We also observe a distinct conductance ‘jump’ at the end of the sliding process, which is further evidence that quantum interference effects dominate charge transport in these single-QD junctions. This conductance ‘jump’ is also confirmed by our theoretical calculations utilizing density functional theory combined with quantum transport theory. Our measurements and theory create a pathway to exploit quantum interference effects in quantum-controlled perovskite materials.
Highlights
The studies of quantum interference effects through bulk perovskite materials at the Ångstrom scale still remain as a major challenge
The extensions of singlemolecule charge transport measurements from conjugated molecular families[13] to molecular assemblies[14,15], clusters[16], and the recently developed Au-halogen interfacial engineering[17] offer an opportunity to gain an insight into microscopic charge transport through Ångstrom-scale perovskite materials. To understand how their macroscopic charge transport properties lead to quantum effects at the nanoscale, here we report the observation of room-temperature Quantum interference (QI) effects in metal halide perovskite quantum dots (QDs) at the Ångstrom scale using the mechanically controllable break junction (MCBJ) technique combined with quantum transport theory and calculations
The tunneling transport through QDs or molecules is mediated by electrons whose energy lies within the energy gap between the highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO), the inter-orbital QI can be understood qualitatively by inspecting the signs of the HOMO and LUMO at the points of contact between the molecule and electrode (Fig. 1a)
Summary
The studies of quantum interference effects through bulk perovskite materials at the Ångstrom scale still remain as a major challenge. The extensions of singlemolecule charge transport measurements from conjugated molecular families[13] to molecular assemblies[14,15], clusters[16], and the recently developed Au-halogen interfacial engineering[17] offer an opportunity to gain an insight into microscopic charge transport through Ångstrom-scale perovskite materials. To understand how their macroscopic charge transport properties lead to quantum effects at the nanoscale, here we report the observation of room-temperature QI effects in metal halide perovskite quantum dots (QDs) at the Ångstrom scale using the mechanically controllable break junction (MCBJ) technique combined with quantum transport theory and calculations
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