Self-Catalyzed Vapor–Liquid–Solid Growth of Lead Halide Nanowires and Conversion to Hybrid Perovskites

Abstract

Lead halide perovskites (LHPs) have shown remarkable promise for use in photovoltaics, photodetectors, light-emitting diodes, and lasers. Although solution-processed polycrystalline films are the most widely studied morphology, LHP nanowires (NWs) grown by vapor-phase processes offer the potential for precise control over crystallinity, phase, composition, and morphology. Here, we report the first demonstration of self-catalyzed vapor-liquid-solid (VLS) growth of lead halide (PbX; X = Cl, Br, or I) NWs and conversion to LHP. We present a kinetic model of the PbX NW growth process in which a liquid Pb catalyst is supersaturated with halogen X through vapor-phase incorporation of both Pb and X, inducing growth of a NW. For PbI, we show that the NWs are single-crystalline, oriented in the ⟨1̅21̅0⟩ direction, and composed of a stoichiometric PbI shaft with a spherical Pb tip. Low-temperature vapor-phase intercalation of methylammonium iodide converts the NWs to methylammonium lead iodide (MAPbI) perovskite while maintaining the NW morphology. Single-NW experiments comparing measured extinction spectra with optical simulations show that the NWs exhibit a strong optical antenna effect, leading to substantially enhanced scattering efficiencies and to absorption efficiencies that can be more than twice that of thin films of the same thickness. Further development of the self-catalyzed VLS mechanism for lead halide and perovskite NWs should enable the rational design of nanostructures for various optoelectronic technologies, including potentially unique applications such as hot-carrier solar cells.

PbI2 Single Crystal Growth and Its Optical Property Study

“…Traditionally, the growth of PbI 2 single crystals can be carried out using the Bridgman−Stockbarger method [9] and the Czochralski method [10]. However, some physical and chemical methods, such as physical vapor deposition (PVD) [11], liquid solution method [12], vapor−liquid−solid method [13], and hydrothermal synthesis [14] have been successfully used to synthesize PbI 2 nanobelts or nanowires. To date, growing PbI 2 single crystals with high chemical and structural quality has been challenging but essential for high performance detectors.…”

Two-step vapor deposition of self-catalyzed large-size PbI2 nanobelts for high-performance photodetectors

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] As a typical layered perovskite derivative, lead iodide (PbI2) has attracted extensive research attention in solar cells, photodetectors and other optoelectronic devices, [14][15][16][17][18][19][20][21][22][23][24][25][26] due to its direct bandgap of 2.28-2.5 eV and tunable optoelectronic properties. 16,[19][20][21][22][23][24][25][26][27] Layered PbI2 material is composed of covalently bonded I-Pb-I repeating units stacked along the c-axis by van der Waals interlayer interaction. 28,29 Up to now, low dimensional PbI2 nanostructures of nanosheets, 19-22, 24, 26 nanowires 19,23,27 and atomically thin monolayers 22 have been prepared by a simple synthesis method of vapor deposition.…”

“…16,[19][20][21][22][23][24][25][26][27] Layered PbI2 material is composed of covalently bonded I-Pb-I repeating units stacked along the c-axis by van der Waals interlayer interaction. 28,29 Up to now, low dimensional PbI2 nanostructures of nanosheets, 19-22, 24, 26 nanowires 19,23,27 and atomically thin monolayers 22 have been prepared by a simple synthesis method of vapor deposition. In the reported vapor deposition of PbI2 nanostructures, one-dimensional (1D) nanowires followed a chemical vapor deposition (CVD) process, 19,23,27 otherwise, two-dimensional (2D) nanosheets followed a physical vapor deposition (PVD) process.…”

Controlled Synthesis and Photonics Applications of Metal Halide Perovskite Nanowires

“…Given the high‐quality Fabry–Pérot cavities, these perovskite NWs were used to achieve low‐threshold lasers. Meyers et al also prepared the hybrid perovskite NWs through a vapor‐phase synthesis method, as shown in Figure a . They reported for the first time the self‐catalyzed vapor–liquid–solid (VLS) growth of PbI 2 NWs using liquid Pb as the catalysts (Figure b–d).…”

“…Scale bars for right: 2 nm −1 . (a)–(f) Reproduced with permission . Copyright 2017, American Chemical Society.…”