Revealing the Role of Tin(IV) Halides in the Anisotropic Growth of CsPbX₃ Perovskite Nanoplates

Abstract

CsPbX3 perovskite nanoplates (PNPLs) were formed in a synthesis driven by SnX4 (X=Cl, Br, I) salts. The role played by these hard Lewis acids in directing PNPL formation is addressed. Sn4+ disturbs the acid–base equilibrium of the system, increasing the protonation rate of oleylamine and inducing anisotropic growth of nanocrystals. Sn4+ cations influence the reaction dynamics owing to complexation with oleylamine molecules. By monitoring the photoluminescence excitation and photoluminescence (PL) spectra of the PNPLs grown at different temperatures, the influence of the thickness on their optical properties is mapped. Time‐resolved and spectrally resolved PL for colloidal dispersions with different optical densities reveals that the dependence of the overall PL lifetime on the emission wavelength do not originate from energy transfer between PNPLs but from the contribution of PNPLs with distinct thickness, indicating that thicker PNPLs exhibit longer PL lifetimes.

Layered metal halide perovskite solar cells: A review from structure‐properties perspective towards maximization of their performance and stability

“…(H) Absorption peak position for different subfamily obtained from horizontal slices of the PLE x PL false‐color graph for each of the samples in (D). The gray line is a simple EMA model considering finite potential confinement (Adapted with permission from Angewandte Chemie, 2020, 132, 11 598) 105 . (I) Temperature‐dependent PL of an (EA)2PbI4 and (J) (PEA)2PbI4 perovskite single crystals.…”

“…The contribution on the emission of each thickness subfamily in this complex layered perovskite matrix was identified combining a thickness distribution histogram, built with careful counting of hundreds of nanoplatelets from images acquired with High‐Angle Annular Dark‐Field‐Scanning Transmission Electron Microscopy (HAADF‐STEM), with the second derivative of the PL spectrum (Figure 5E,F). 105 The absorption band edges of these samples were also monitored by mapping the excitation versus PL spectra of the sample (Figure 5G), allowing the discrimination of each population of nanoplatelets with a different thickness by the position of their excitonic resonance. Figure 5H shows the absorption peak position for each nanoplatelet thickness according to the excitation versus PL maps acquired for each sample in Figure 5D.…”

Stacks of a Hidden Treasure: on the Self-Assemble of Perovskite Nanoplates in Organic Solvents

“…For CsPbI3 compositions, the I-110 sample shows predominantly n = 3 excitonic absorption (λexc = 587 nm), while I-170 shows a mixture of larger particles together with the n = 3 excitonic resonance. 31 Regarding the PL spectra, the samples synthesized at 110 °C show more intense emissions from the main excitonic state: n = 2 for Br-110 (λmax = 439 nm) and n = 3 for I-110 (λmax = 606 nm). The latter also shows a shoulder of n = 4 emission.…”

“…We synthesized the nanoplates with different compositions and different temperatures, following a protocol previously reported by our group. 31 Briefly, lead acetate and cesium carbonate are dissolved in 1-octadecene, oleic acid, and oleylamine, and a second solution of SnX4 (X = Br or I) is prepared separately in the same mixture of solvents. The SnX4 solution (halide precursor) is swiftly injected into the lead/cesium precursor in the desired temperature to yield PNPls.…”

Towards Engineering Intrinsic Linewidths and Line-Broadening in Perovskite Nanoplatelets

“…CsPbI 3 nanoplatelets were synthesized according to a procedure detailed elsewhere. 41 Briefly, 15 mg of Cs 2 CO 3 and 158 mg of Pb(acetate) 2 3H 2 O were loaded into 50 mL, 3-neck flask along with 1 mL of oleic acid (OA), 0.5 mL of oleylamine (OLA) and 4.5 mL of 1-octadecene (1-ODE). The mixture was kept at 100 • C for 1 hour under reduced pressure.…”