Spectral Stable Blue-Light-Emitting Diodes via Asymmetric Organic Diamine Based Dion–Jacobson Perovskites

Abstract

The spectral instability issue is a challenge in blue perovskite light-emitting diodes (PeLEDs). Dion–Jacobson (DJ) phase perovskites are promising alternatives to achieve high-quality blue PeLEDs. However, the current exploration of DJ phase perovskites is focused on symmetric divalent cations, and the corresponding efficiency of blue PeLEDs is still inferior to that of green and red ones. In this work, we report a new type of DJ phase CsPb(Br/Cl) 3 perovskite via introduction of an asymmetric molecular configuration as the organic spacer cation in perovskites. The primary and tertiary ammonium groups on the asymmetric cations bridge with the lead halide octahedra forming the DJ phase structures. Stable photoluminescence spectra were demonstrated in perovskite films owing to the suppressed halide segregation. Meanwhile, the radiative recombination efficiency of charges is improved significantly as a result of the confinement effects and passivation of charge traps. Finally, we achieved an external quantum efficiency of 2.65% in blue PeLEDs with stable spectra emission under applied bias voltages. To our best knowledge, this is the first report of asymmetric cations used in PeLEDs, which provides a facile solution to the halide segregation issue in PeLEDs.

Strategies to Improve the Stability of Perovskite Light-Emitting Diodes: Progress and Perspective

“…Similarly, several other organic ligands have been proposed for producing stable 2D DJ MHPs, such as asymmetric N,N-dimethyl-1,3-propanediamine (DPDA) and conjugated 2-fluoro-[1,1′-biphenyl]-4,4′-diyl)-dimethanaminium (FPP). 62,63 Furthermore, those ligand engineering methods intended for optimized 2D phase distribution as presented in Defect Suppression of MHPs were also proved to be favorable for enhancing the EL stability of 2D/quasi 2D PeLEDs.…”

“…Compared with commonly used PEABr, the stronger binding force between P-PDABr 2 and [PbBr 6 ] 4– octahedrons led to stable low-dimensional domains, thereby improving the spectral stability of deep-blue PeLEDs. Similarly, several other organic ligands have been proposed for producing stable 2D DJ MHPs, such as asymmetric N , N -dimethyl-1,3-propanediamine (DPDA) and conjugated 2-fluoro-[1,1′-biphenyl]-4,4′-diyl)-dimethanaminium (FPP). , Furthermore, those ligand engineering methods intended for optimized 2D phase distribution as presented in Defect Suppression of MHPs were also proved to be favorable for enhancing the EL stability of 2D/quasi 2D PeLEDs.…”

Process‐Aid Solid Engineering Triggers Delicately Modulation of Y‐Series Non‐Fullerene Acceptor for Efficient Organic Solar Cells

“…Asymmetric geometry is comprehensively furnished in organic and perovskite optoelectronic fields (such as light‐emitting diodes, solar cells) as it can provide distinct dipole effects and 3D spatial configurations. [ 26–31 ] In this work, a novel process‐aid solid (PAS) engineering is proposed by applying asymmetric configuration on volatile solid, where a volatile 1,3‐dibromo‐5‐chlorobenzene (DBCl) solid (shown in Figure a) with asymmetric halogen around benzene ring is selected to construct the high‐performance organic solar cells. The key superiority of PAS engineering is the elevated dipole moment, unidentical dipole direction and evident interlaminar noncovalent interaction after coupling asymmetric DBCl with BTP core in Y‐series small molecule.…”

Improved highly efficient Dion–Jacobson type perovskite light-emitting diodes by effective surface polarization architecture

“…[13][14][15][16][17] Although a wide emission spectral region from blue to NIR has been reported, investigations into DJ-type PeLEDs are still rare compared to RP-type ones. 12,[18][19][20][21][22][23] Qi et al used a propane-1,3-diammonium cation to fabricate blue emission devices and got an EQE of 8.5% by optimization. They also found that when they added chloride ions to tune the emission for shorter wavelength, phase segregation appeared during operation.…”

“…13–17 Although a wide emission spectral region from blue to NIR has been reported, investigations into DJ-type PeLEDs are still rare compared to RP-type ones. 12,18–23…”