Temperature-Responsive Photoluminescence and Elastic Properties of 1D Lead Halide Perovskites R- and S-(Methylbenzylamine)PbBr3

Abstract

Low-dimensional metal halide perovskites (MHPs) have received much attention due to their striking semiconducting properties tunable at a molecular level, which hold great potential in the development of next-generation optoelectronic devices. However, the insufficient understanding of their stimulus-responsiveness and elastic properties hinders future practical applications. Here, the thermally responsive emissions and elastic properties of one-dimensional lead halide perovskites R- and S-MBAPbBr₃ (MBA⁺ = methylbenzylamine) were systematically investigated via temperature-dependent photoluminescence (PL) experiments and first-principles calculations. The PL peak positions of both perovskites were redshifted by about 20 nm, and the corresponding full width at half maximum was reduced by about 40 nm, from ambient temperature to about 150 K. This kind of temperature-responsive self-trapped exciton emission could be attributed to the synergistic effect of electron-phonon coupling and thermal expansion due to the alteration of hydrogen bonding. Moreover, the elastic properties of S-MBAPbBr₃ were calculated using density functional theory, revealing that its Young's and shear moduli are in the range of 6.5-33.2 and 2.8-19.5 GPa, respectively, even smaller than those of two-dimensional MHPs. Our work demonstrates that the temperature-responsive emissions and low elastic moduli of these 1D MHPs could find use in flexible devices.

Keywords: elastic property; low-dimensional; metal halide perovskite; photoluminescence; stimulus-responsive.

Figure 1

The structure of MBAPbBr₃. (a) The molecular structure scheme of methylbenzylamine. (b,c) Hydrogen bonds between the [PbBr₃]⁻ chain and methylbenzylamine in MBAPbBr₃. (d,e) The structures of R-MBAPbBr₃ (d) and S-MBAPbBr₃ (e) along the b-axis.

Figure 2

The PL properties of R- and S-MBAPbBr₃. (a) PL spectra at 296 K excited by a 325 nm laser. (b) The CIE coordinates of PL. (c) The configuration coordinate models of PL. FE: free exciton, GS: ground state, E_g: bandgap, E_st: self-trapped energy, E_d: lattice distortion energy, E_PL: emission energy.

Figure 3

(a,b) The PL spectra of R-MBAPbBr₃ (a) and S-MBAPbBr₃ (b) at various temperatures. (c) The maximum wavelengths of R- and S-MBAPbBr₃ at different temperatures. (d) The FWHMs of R- and S-MBAPbBr₃ at different temperatures.

Figure 4

3D and 2D representations of Young’s moduli (a,b) and shear moduli (c,d) of S-MBAPbBr₃. In (c), the transparent outer layer and the nontransparent inner layer denote the maximum and minimum values, respectively. The blue outer line and red inner line in (d) denote the maximum and minimum values, respectively.