Anion Exchange in Cesium Lead Halide Perovskite Nanocrystals and Thin Films Using Trimethylsilyl Halide Reagents

Synthesis of TlBr and Tl2AgBr3 Nanocrystals

“…TlBr nanocrystals were synthesized by adding TMSBr to a hot reaction mixture of Tl(CH 3 COO) 3 or Tl(CH 3 COO) in OA, OAm and ODE. TlBr results from a metathesis reaction and the spontaneous decomposition of TlBr 3 to TlBr, …”

“…TMSBr was explored as the halide source because it is known to provide a relatively fast reaction rate compared to other halides due to the strong affinity of TMS for acetate …”

“…The need for short reaction times is similar to other metal halides, such as CsPbI 3 or Cs 2 AgBiBr 6 . Perhaps rapid quenching of nanocrystal growth reactions is more generally necessary for perovskite and related metal halide nanocrystals with tertiary or quaternary composition than binary compounds . Perhaps it will be possible to mitigate TlBr formation at the higher reaction temperatures with further optimization of the reactant concentrations, similar to double perovskites …”

Facile anion-exchange reaction in mixed-cation lead bromide perovskite nanocrystals

“…Compared to most of the reported methods, this one is facile, fast and environmentally friendly. [16][17][18][19][20][21][22][23][24] The halide precursors do not need any solvent to be dissolved in, they can be separated by a simple ltration and, most relevant, the reaction can be carried out at room temperature and under ambient conditions. The products were characterized by means of X-ray diffraction, UV absorbance, photoluminescence and high resolution TEM.…”

“…[7][8][9][10][11][12][13][14][15] However, appealing post-synthetic strategies rely on the anion exchange of the prepared colloidal nano-dispersions, as it has been previously demonstrated on CsPbBr 3 . [16][17][18][19][20][21][22] One of the most common routes for anion exchange in lead halide nanocrystal was reported by Nedelcu et al and makes use of Schlenk line where lead halogens and OAmX as anion sources were mixed with octadecene (ODE) in neck ask and kept under vacuum at 120 C. The dried oleic acid (OA) and oleylamine (OLA) were injected at 120 C under N 2 ow. 17 While this approach is highly suitable to provide a full anion exchange, it would be desirable to provide more easy and facile routes to perform such anion modication on lead halide nanocrystals and also provide evidence of such exchange on mixed cation compositions.…”