White-Light Emission and Structural Distortion in New Corrugated Two-Dimensional Lead Bromide Perovskites

Abstract

Hybrid inorganic-organic perovskites are developing rapidly as high performance semiconductors. Recently, two-dimensional (2D) perovskites were found to have white-light, broadband emission in the visible range that was attributed mainly to the role of self-trapped excitons (STEs). Here, we describe three new 2D lead bromide perovskites incorporating a series of bifunctional ammonium dications as templates which also emit white light: (1) α-(DMEN)PbBr (DMEN = 2-(dimethylamino)ethylamine), which adopts a unique corrugated layered structure in space group Pbca with unit cell a = 18.901(4) Å, b = 11.782(2) Å, and c = 23.680(5) Å; (2) (DMAPA)PbBr (DMAPA = 3-(dimethylamino)-1-propylamine), which crystallizes in P2/c with a = 10.717(2) Å, b = 11.735(2) Å, c = 12.127(2) Å, and β = 111.53(3)°; and (3) (DMABA)PbBr (DMABA = 4-dimethylaminobutylamine), which adopts Aba2 with a = 41.685(8) Å, b = 23.962(5) Å, and c = 12.000(2) Å. Photoluminescence (PL) studies show a correlation between the distortion of the "PbBr" octahedron in the 2D layer and the broadening of PL emission, with the most distorted structure having the broadest emission (183 nm full width at half-maximum) and longest lifetime (τ = 1.39 ns). The most distorted member α-(DMEN)PbBr exhibits white-light emission with a color rendering index (CRI) of 73 which is similar to a fluorescent light source and correlated color temperature (CCT) of 7863 K, producing "cold" white light.

Organic–inorganic metal halide hybrids beyond perovskites

“…In 2014, intrinsic, broadband white-light emission was observed from the corrugated-2D lead-halide perovskites (N-MEDA)PbBr 4 and (EDBE)PbX 4 (N-MEDA = N 1 -methylethane-1,2-diammonium; EDBE = 2,2 -(ethylenedioxy)bis(ethylammonium); X = Cl and Br) (Figure 6(a)). In addition to '2 × 2' corrugated 2D structure, this family has been extended to '3 × 3' [109] (Figure 6(b)) and '4 × 4' [110] types. More recently, corrugated-2D perovskites have been used to stabilize the α-CsPbI 3 phase and achieve a record PCE of 11.8% by connecting α-CsPbI 3 crystallites for effective electron transfer and passivating the surface defects [111].…”

Pressure‐Induced Broadband Emission of 2D Organic–Inorganic Hybrid Perovskite (C6H5C2H4NH3)2PbBr4

“…[14] The exciton self-trapping associated with inorganic lattice distortions and strong excitonphonon coupling cause broad emission with a large Stokes shift. [14] The exciton self-trapping associated with inorganic lattice distortions and strong excitonphonon coupling cause broad emission with a large Stokes shift.…”

Compositional and Solvent Engineering in Dion–Jacobson 2D Perovskites Boosts Solar Cell Efficiency and Stability

“…[16,17,[21][22][23][24][25] The long-term stability of 3D halide perovskites with organic cations is still an open issue and under intense investigation. [26][27][28][29][30] 2D perovskites adopt a general formula of A′ 2 A n−1 M n X 3n+1 or BA n−1 M n X 3n+1 , where A′ and A are univalent organic cations, B is a divalent organic cation, M is a divalent metal, and X is a halide ion. 2D halide perovskites with bulky organic cations are attracting attention because of their better moisture resistance by the protection of the hydrophobic organic spacer layer.…”