Ultrathin Colloidal Cesium Lead Halide Perovskite Nanowires

Abstract

Highly uniform single crystal ultrathin CsPbBr nanowires (NWs) with diameter of 2.2 ± 0.2 nm and length up to several microns were successfully synthesized and purified using a catalyst-free colloidal synthesis method followed by a stepwise purification strategy. The NWs have bright photoluminescence (PL) with a photoluminescence quantum yield (PLQY) of about 30% after surface treatment. Large blue-shifted UV-vis absorption and PL spectra have been observed due to strong two-dimensional quantum confinement effects. A small angle X-ray scattering (SAXS) pattern shows the periodic packing of the ultrathin NWs along the radial direction, demonstrates the narrow radial distribution of the wires, and emphasizes the deep intercalation of the surfactants. Despite the extreme aspect ratios of the ultrathin NWs, their composition and the resulting optical properties can be readily tuned by an anion-exchange reaction with good morphology preservation. These bright ultrathin NWs may be used as a model system to study strong quantum confinement effects in a one-dimensional halide perovskite system.

Organic–inorganic metal halide hybrids beyond perovskites

“…In 2016, highly uniform single crystalline ultrathin CsPbX 3 nanowires were synthesized by the same group with high photoluminescence quantum efficiencies (PLQEs) [9]. The stable colloidal solutions of CH 3 NH 3 PbX 3 nanoparticles with size below 10 nm were first reported in 2014 [10], which stimulated tremendous research interest in perovskite quantum dots.…”

Metal halide perovskite nanocrystals and their applications in optoelectronic devices

“…Semiconductor NWs with diameters smaller than their exciton Bohr radii have unique properties to combine the radial size of atomic level with the length of micron scale. In addition, their high specific surface area makes them candidates for various optoelectronic devices, such as photodetectors and optically pumped lasers . Compared with the chemical vapor deposition method (based on the vapor‐liquid‐solid) mechanism in which noble metal films are used as catalysts to drive the growth of one‐dimensional crystals) of II‐VI and III‐V semiconductor NWs, the synthesis of metal halides perovskite NWs is more convenient .…”

“…Yang's group synthesized CsPbBr 3 NCs by hot injection, then a step‐wise purification strategy was applied in order to purify the NWs with a uniform diameter of 2.2 ± 0.2 nm. The process comprises the following steps: the supernatant after the first centrifugation was mixed with ethyl acetate antisolvent in different volumes and was centrifuged several times to obtain NWs with different radial distributions (Figure A‐D) . However, the purification process can peel off the bound ligands and destroy the surface passivation, resulting in more surface states and low PL QYs.…”

Combination of solution-phase process and halide exchange for all-inorganic, highly stable CsPbBr3 perovskite nanowire photodetector

“…In the family of halide perovskites, CsPbBr 3 is particularly attractive in the field of photodetectors and light-emitting diodes due to its suitable band gap and high quantum efficiency [14,29]. Thus, nanowires based on CsPbBr 3 have been reported widely [28,[30][31][32][33]. In these reports, most of the nanowires were prepared by the traditional hot-injection technique [32], but when these nanowires are used for films, complex vacuum coating technology will be necessary [26].…”

“…In these reports, most of the nanowires were prepared by the traditional hot-injection technique [32], but when these nanowires are used for films, complex vacuum coating technology will be necessary [26]. Also, high-speed centrifugation, used to improve the purity of nanowires, may destroy the ligands [31]. Additionally, nanocrystals will be synthesized firstly before the preparation of nanowires, in which redundant nanosheets will exist in this process [12].…”