Abstract
Thin films based on two-dimensional metal halide perovskites have achieved exceptional performance and stability in numerous optoelectronic device applications. Simple solution processing of the 2D perovskite provides opportunities for manufacturing devices at drastically lower cost compared to current commercial technologies. A key to high device performance is to align the 2D perovskite layers, during the solution processing, vertical to the electrodes to achieve efficient charge transport. However, it is yet to be understood how the counter-intuitive vertical orientations of 2D perovskite layers on substrates can be obtained. Here we report a formation mechanism of such vertically orientated 2D perovskite in which the nucleation and growth arise from the liquid–air interface. As a consequence, choice of substrates can be liberal from polymers to metal oxides depending on targeted application. We also demonstrate control over the degree of preferential orientation of the 2D perovskite layers and its drastic impact on device performance.
Highlights
Thin films based on two-dimensional metal halide perovskites have achieved exceptional performance and stability in numerous optoelectronic device applications
=(AC=l−,CBHr3−N, HI−3+),to bulky long-chain ammonium cations are introduced to confine layers of metal halide octahedra in two dimensions. 2D Metal halide perovskites (MHPs) exhibit many of the superb optoelectronic properties of their 3D counterparts while providing an opportunity to tune the properties by controlling the thickness of the metal halide layers through the quantum confinement effect[32]
The precursor solution was prepared by dissolving stoichiometric amounts of lead iodide (PbI2), methylammonium iodide (MAI), and butylammonium iodide (BAI) in dimethylacetamide (DMAc) solvent
Summary
Thin films based on two-dimensional metal halide perovskites have achieved exceptional performance and stability in numerous optoelectronic device applications. A key to high device performance is to align the 2D perovskite layers, during the solution processing, vertical to the electrodes to achieve efficient charge transport. A critical requirement for high-performance 2D MHP optoelectronic devices is to align the 2D MHP layers perpendicular to the electrode layers. This is because the bulky ammonium cations that separate the 2D metal halide slabs are electrically insulating. For devices such as solar cells and LEDs, wherein the MHP thin films are sandwiched between electrodes, vertical alignment of 2D
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