2D Ruddlesden-Popper X-FPEA2PbI4 perovskites for highly stable PeLED with improved opto-electro-mechanical properties

Abstract

We investigate the opto-electro-mechanical characteristics and stability of Ruddlesden-Popper X-FPEA₂PbI₄ perovskites, where X represents para (p), meso (m), and ortho (o) configurations. The findings reveal that the transition from para to meso and ortho configurations results in a progressive increase in the bandgap, with values of 2.097 eV, 2.133 eV, and 2.177 eV, respectively. Notably, p-FPEA₂PbI₄ exhibits superior stability, characterized by an enhanced formation energy of - 4.825 eV, compared to m-FPEA₂PbI₄ (- 4.647 eV) and o-FPEA₂PbI₄ (- 4.581 eV). Thus, p-FPEA₂PbI₄ emerges as a leading candidate for the active layer in perovskite light-emitting diodes (PeLEDs). Internal quantum efficiencies of 6.289% for PEA₂PbI₄ and 2.285% for p-FPEA₂PbI₄ have been achieved, both of which are higher than those of MAPbI₃. In contrast, the dependence of efficiency on temperature fluctuations for p-FPEA₂PbI₄ is 0.01 1/K, compared to PEA₂PbI₄'s 0.0282 1/K, highlighting its enhanced stability under temperature changes. Furthermore, the stability of the emission spectrum against temperature fluctuations for p-FPEA₂PbI₄, with a value of 0.0156 nm/K, is greater than that of PEA₂PbI₄, which has a value of 0.0245 nm/K. Although the efficiency of PeLEDs utilizing p-FPEA₂PbI₄ is somewhat lower than that of PEA₂PbI₄, its superior stability makes it a compelling choice for future applications, paving the way for more reliable and durable light-emitting devices.

Keywords: Density functional theory; Finite element method; Perovskite light-emitting diodes; Ruddlesden–Popper two-dimensional perovskites; Stability.

Fig. 1

Algorithm of SCF for solving the KS equation.

Fig. 2

Crystal structure and lattice parameters of X-FPEA₂PbI₄.

Fig. 3

The aromatic spacer cation of (a) p-FPEA, (b) m-FPEA, and (c) o-FPEA.

Fig. 4

Thermal stability of X-FPEA₂PbI₄ (X = p, m, and o) using AIMD simulation.

Fig. 5

Complex refractive index for X-FPEA₂PbI₄ (a) X = p, (b) X = m, and (c) X = o and dielectric function for X-FPEA₂PbI₄ (d) X = p, (e) X = m, and (f) X = o.

Fig. 6

Band structure and bandgap energy of X-FPEA₂PbI₄ (a) X = p, (b) X = m, and (c) X = o without spin–orbit coupling effect.

Fig. 7

Band structure and bandgap energy of X-FPEA₂PbI₄ (a) X = p, (b) X = m, and (c) X = o with SOC effect.

Fig. 8

(a) Schematic of PeLED and (b) The different structures of PeLEDs and energy levels of ETL, HTL, and active layer.

Fig. 9

The IQE values of PeLED for different ETLs and HTLs for (a) MAPbI₃, (b) PEA₂PbI₄, and (c) p-FPEA₂PbI₄.

Fig. 10

The IQE of PeLED for different temperatures for (a) MAPbI₃, (b) PEA₂PbI₄, and (c) p-FPEA₂PbI₄.

Fig. 11

The EQE of PeLED with different active layers (a) MAPbI₃, (b) PEA₂PbI₄, and (c) p-FPEA₂PbI₄.

Fig. 12

The L–I curve of PeLED for different active layers (a) MAPbI₃, (b) PEA₂PbI₄, and (c) p-FPEA₂PbI₄.

Fig. 13

The spontaneous emission of PeLED with different active layers (a) MAPbI₃, (b) PEA₂PbI₄, and (c) FPEA₂PbI₄.

Fig. 14

The spontaneous emission of PeLED for different currents for (a) MAPbI₃, (b) PEA₂PbI₄, and (c) FPEA₂PbI₄.

Fig. 15

The CIE 1931 chromatic coordinates for the PeLEDs with (a) MAPbI₃, (b) PEA₂PbI₄, and (c) FPEA₂PbI₄.