Fluorinated Spacers Regulate the Emission and Bandgap of Two-Dimensional Single-Layered Lead Bromide Perovskites by Hydrogen Bonding

Abstract

In this work, four kinds of two-dimensional single-layered F-substituted ethylammonium lead halide perovskites (LHPs, (F x CH3–x CH2NH3)2PbBr4, x = 0, 1, 2, and 3) are successfully synthesized. The introduction of terminal F atoms promotes the formation of an inter- and intramolecular hydrogen bonding network, which has a great impact on the configuration of F-substituted EA, the interlayer spacing, and distortion of inorganic layers. Among these four as-prepared samples, (FCH2CH2NH3)2PbBr4 shows the smallest bandgap (∼2.72 eV) and best photoconductivity because of the interlayer electronic coupling. Owing to the strong coupling between excitons and lattice, intense white light emission (quantum yield: 12%) is observed for (F2CHCH2NH3)2PbBr4. Benefiting from the hydrophobic nature of F–C bonds, (CF3CH2NH3)2PbBr4 presents a greatly improved stability toward moisture. These findings reveal that constructing inter- and intramolecular interaction can serve as an effective approach for tuning the broadband emission and the interlayer conductivity of single-layered LHPs.

Ultrafast Study of Exciton Transfer in Sb(III)-Doped Two-Dimensional [NH3(CH2)4NH3]CdBr4 Perovskite

“…Even for Cd-PVK-15%Pb (Figure S12), the XB before t 0 still remains, consistent with the corresponding PL spectrum, in which the peak of 380 nm is still observed (Figure S11). Interestingly, a new bleach peak (XB2) located at 390 nm (Figure S12b) appears, in good agreement with the absorption of 2D [PbBr 6 ] 4– . , These results corroborate the ET-induced Sb 3+ triplet emission in Cd-PVK-0.1%Sb and weak electronic coupling between [CdBr 6 ] 4– and [PbBr 6 ] 4– octahedra that benefits the STEs emission.…”

Structure‐Property Relationships and Idiosyncrasies of Bulk, 2D Hybrid Lead Bromide Perovskites

“…around 2.72 eV and the best photoconductivity owing to the interlayer electronic coupling, as well as the smallest distortions of the equatorial PbÀ BrÀ Pb angles among the studied fluoro-substituted analogues. [103] While (F 3 CH 2 CH 2 NH 3 ) 2 PbBr 4 manifested comparatively, the greatest moisture stability. [103] Another interesting class is thin-layer lead bromide perovskites incorporating unsaturated hydrocarbon within the amine molecules that provide a synthetic paradigm to perform small molecule reactivity in the solidstate (Table 1).…”

“…[103] While (F 3 CH 2 CH 2 NH 3 ) 2 PbBr 4 manifested comparatively, the greatest moisture stability. [103] Another interesting class is thin-layer lead bromide perovskites incorporating unsaturated hydrocarbon within the amine molecules that provide a synthetic paradigm to perform small molecule reactivity in the solidstate (Table 1). [104][105] Karunadasa and colleagues, demonstrated the reversible iodination of alkene molecules in the hybrid perovskites (BEA) 2 PbBr 4 and (BYA) 2 PbBr 4, where BEA: but-3-enammonium and BYA: but-3-ynammonium.…”

“…As discussed above, structurally and synthetically, the majority of bulk, lead bromide perovskites reported are the thin-layered (n = 1) members. [55,[88][89][91][92][93][95][96][97][102][103][104][105]113,[123][124][125][126][128][129][141][142][143][144][145][146][147] In the early 1990s, Thorn and colleagues report the first evidence of thick-layer lead halide perovskites (n > 1) by producing films of (C 9 H 19 NH 3 ) 2 (CH 3 NH 3 )Pb 2 I 7 and (C 9 H 19 NH 3 ) 2 (CH 3 NH 3 ) nÀ 1 Pb n Br 3n + 1 (n = 1-3) series with the nonylammonium spacer cation, along with films of (PhNH 3 ) 2 (CH 3 NH 3 )Pb 2 I 7 with Ph: phenylammonium. [148] Although unable to obtain single crystal structures at the time, Thorn and colleagues noted the excitonic absorption peak of (C 9 H 19 NH 3 ) 2 (CH 3 NH 3 )Pb 2 Br 7 films at 430 nm and (C 9 H 19 NH 3 ) 2 (CH 3 NH 3 ) 2 Pb 3 Br 10 at 450 nm, lower in energy than their n = 1 member.…”

“…[102] The ethylamine molecule has also been subjected to fluorination where a series of n = 1 fluor-substituted lead bromide perovskites were studied: (F x CH 3À x CH 2 NH 3 ) 2 PbBr 4 , x = 0, 1, 2, and 3) as seen in Table 1. [103] The position of the terminal F atom directs the formation of an inter-and intramolecular hydrogen bonding, distortions within the inorganic layers, interlayer distance and configuration of the fluoro-substituted ethylammonium spacer. (FCH 2 CH 2 NH 3 ) 2 PbBr 4 showed the smallest bandgap value of C2/c 5,5'''-bis(aminoethyl)-2,2':5',2'':5'',2'''-Quaterthiophene (AEQT: C 16 H 10 S 4 ) (no broadband emission), m-FA 2 PbBr 4 [139] (110), (110) 2 × 2…”