Controlled Synthesis of Composition Tunable Formamidinium Cesium Double Cation Lead Halide Perovskite Nanowires and Nanosheets with Improved Stability

Abstract

Lead halide perovskites with well-defined morphology have attracted attention for their unique properties as a promising new class of semiconductor materials in photovoltaics and optoelectronics. However, controlling morphologies and compositions of perovskite nanostructures with improved stability, especially for double cation lead halide perovskite, still remains a challenge. Here, we demonstrate a colloidal synthetic approach for direct synthesis of stable singlecrystal formamidinium (FA) cesium double cation lead halide FA 0.33 Cs 0.67 PbBr 3−x I x (0 ≤ x ≤ 3) perovskite nanostructures with controllable morphology over a wide range of halide compositions, without using a previous anion-exchange process. The presence of FA alloyed in the A site for the pure cesium lead halide perovskite structure can stabilize the nanocrystals while delivering a better balance between structure and composition. On the basis of the FA 0.33 Cs 0.67 PbBr 3−x I x alloy perovskite system, we achieved nanowires and nanosheets with high yield of various halide compositions by tuning the ligand participating in the reaction. These new perovskite nanostructures with well-defined morphology and compositions demonstrated improved stability and fluorescent and optoelectronic properties, which may allow them to find application as replacements for conventional semiconductor nanostructures in nanoscale devices.

Halide Perovskite Nanocrystals for Next‐Generation Optoelectronics

“…g) Schematic illustration for the formation of perovskite nanowires and nanosheets NCs. Reproduced with permission . Copyright 2017, American Chemical Society.…”

“…Moreover, by using large amount of OLA, the PNC surface became more protected in all directions and formed nanocubes, while otherwise nanorods were formed (Figure f) . Wang's group found that by tuning the ligand participating in the reaction such as changing the amount of OAC and oleylamine, different shapes of PNCs can be achieved, such as nanowires or nanosheets (Figure g) . Since halide atoms can easily escape from the PNCs, resulting in their poor stability, surface passivation can be used to form more stable halide–hydrogen bonds on the surface, which could inhibit the capture of the excited electrons .…”

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

“…Fortunately, we can reduce breakage of nanowires by optimizing the parameters, such as growth time and the concentration of the solution during anion exchange. Compared with the previous reports, a large number of nanowires being fractured [32,33], and bottom of nanowires films becoming turbid owing to high temperatures [35], our method can protect the morphology of nanowires successfully and provide convenience for fabricating nanowire-based devices.…”

“…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].…”

“…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]. Also, high-speed centrifugation, used to improve the purity of nanowires, may destroy the ligands [31].…”