Metal Halide Perovskite Nanorods: Shape Matters

Abstract

have a soft and ionic lattice. [3] Such ionic nature makes it possible to conduct anion exchange reactions from one kind of perovskite NCs, for example CsPbBr 3 , to another and thus achieve particles with different compositions such as CsPbCl 3 , CsPbI 3 , and their mixed-anion alloys, which is changing to accomplish for conventional semiconductor NCs. This enables bandgap tuning over the whole visible and even near-infrared spectral ranges while maintaining the size and morphology of the resulting NCs. [4] However, their ionic nature also makes the growth rates of perovskites extremely fast, with a completion of the NC growth ranging from less than a second to a couple of seconds. [5] The fast growth rate makes it difficult to control the final shape of perovskite NCs, [6] which will be elaborated upon in detail in this article further below. Useful properties of 1D semiconductor nanorods (NRs) including linearly polarized light emission, reduced lasing threshold, and improved charge transport [6] make them stand out from semiconductor NCs of other morphologies in a variety of applications such as liquid crystal displays (LCDs), lasers, solar cells and photocatalysis. [7] For example, aligned CdSe/CdS NRs incorporated in thin polymer films have been proposed as optical enhancement films to improve the brightness and broaden the color gamut of LCDs. [7b-d] In addition, CdSe/CdS, alloyed CdSe x S 1−x and CsPbBr 3 NRs have demonstrated a relatively low amplified spontaneous emission (ASE) threshold and a high net optical gain at a medium or low pump intensity, making them capable of producing lasing with low pumping thresholds. [7a,8] Furthermore, the 1D character of semiconductor NRs benefits efficient charge separation and provides specific spatial locations for selective deposition of other materials to realize 1D heterostructures, with prominent potentials in optoelectronics and photocatalysis. [9] Although there are a few documented attempts for the controlled chemical growth of perovskite NRs, [6b,7a,10] research into this area is still in its infancy. A high-degree of control during the synthesis of perovskite NRs in terms of size, aspect ratio, and performance, is not yet been fully realized. It is desirable to develop facile, robust, and scalable synthetic strategies for the preparation of high-quality perovskite NRs, to enrich the existing knowledge of their growth mechanisms, and to improve their optical and electronic properties that underpin their future applications. Quasi-1D metal halide perovskite nanorods (NRs) are emerging as a type of materials with remarkable optical and electronic properties. Research into this field is rapidly expanding and growing in the past several years, with significant advances in both mechanistic studies of their growth and widespread possible applications. Here, the recent advances in 1D metal halide perovskite nanocrystals (NCs) are reviewed, with a particular emphasis on NRs. At first, the crystal structures of perovskites are elaborated, which is followed by a revi...

The Impact of Precursor Ratio on the Synthetic Production, Surface Chemistry, and Photovoltaic Performance of CsPbI3 Perovskite Quantum Dots

“…[ 1–5 ] CsPbX 3 QDs exhibit excellent optical properties such as high photoluminescence quantum yields (PLQYs), narrow full width at half‐maximum (FWHM), and tunable bandgaps, which is comparable or even superior to state‐of‐the‐art CdSe QDs with sophisticated shelling or surface passivation, showing huge potential for lighting/display applications. [ 1,2,5–11 ] Recently, it was demonstrated that CsPbI 3 QDs can keep a stable black phase at room temperature, [ 12 ] whereas bulk CsPbI 3 will convert to a nonperovskite yellow phase ( δ ‐phase) with unfavorable optoelectronic properties at the temperature below 320 °C. In addition to the extraordinary phase stability, CsPbI 3 QDs also possess superior thermal stability over the widely studied organic–inorganic hybrid perovskites.…”

Core/Shell Metal Halide Perovskite Nanocrystals for Optoelectronic Applications

“…In recent years, halide perovskite nanocrystals (NCs) have attracted significant attention in both fundamental research and industrial applications, owing to their excellent optical and electronic properties including tunable emission across the UV–vis spectral range, high extinction coefficient, narrow luminescence line width, high photoluminescence quantum yield (PLQY), and high defect tolerance. [ 1–4 ] These intrinsic properties make them promising candidates for a wide range of applications, such as light‐emitting diodes (LEDs), [ 5–7 ] lasers, [ 8,9 ] photodetectors, [ 10 ] biological probes, [ 11 ] solar cells, [ 12 ] and photocatalysis. [ 13 ] In particular, their remarkable optoelectronic performances render them a possible game‐changer.…”

“…luminescence line width, high photoluminescence quantum yield (PLQY), and high defect tolerance. [1][2][3][4] These intrinsic properties make them promising candidates for a wide range of applications, such as light-emitting diodes (LEDs), [5][6][7] lasers, [8,9] photodetectors, [10] biological probes, [11] solar cells, [12] and photocatalysis. [13] In particular, their remarkable optoelectronic performances render them a possible game-changer.…”

Size-tunable and stable cesium lead-bromide perovskite nanocubes with near-unity photoluminescence quantum yield

“…2,3,4 Lead-halide perovskite NCs combine high photoluminescence quantum yields (PLQYs) with narrow emission profiles and tunable fluorescence related to the halide composition 5 or to morphology. 6 On the other hand, although lead-halide perovskite NCs can tolerate a relatively large concentration of defects without compromising their semiconducting properties, 7 the achievement of near-unity PLQYs is severely undermined by halide vacancies 8 prevalently placed at their surface. 9,10,11 In order to cope with this issue, it has recently been proposed, in the course of the synthesis, to separately combine the precursors of the three elements (cesium, lead and the halides) composing the CsPbX 3 NCs, thus allowing to establish the proper halide-rich synthetic conditions, 12 difficultly attainable by using the common approach based on the use of PbX 2 salts as both lead and halide source.…”