Efficient Light‐Emitting Diodes via Hydrogen Bonding Induced Phase Modulation in Quasi‐2D Perovskites

Abstract

Quasi‐2D perovskites have drawn considerable attention in light‐emitting diodes due to their tunable energy landscape, efficient luminescence, and structural diversity. However, the excessive formation of low‐n (n ≤ 2) phases leads to lower carrier injection efficiency arising from the large injection barrier. Meanwhile, inefficient energy transfer caused by undesirable phases distribution results in multipeak emission. In this study, polar anti‐solvent is used that can interact with spacer cations via strong hydrogen bonding, tailoring phases distribution to address the issue. The ethyl acetate treatment induces preferential growth of large‐n phases and enhances energy transfer due to the strong hydrogen bonding energy ≈ −17 kcal mol−1. Leveraging these insights, efficient sky‐blue and green perovskite light‐emitting diodes are developed with improved external quantum efficiency ranging from 4.21% to 8.77%. The anti‐solvent treatment can open up a new avenue to regulate the phase distribution for an efficient energy funnel effect.

Improving Green Perovskite Nanoplate Light-Emitting Diode Performance via Precision Passivation and Phase Distribution Management

“…This supersaturated state facilitates the nucleation and precipitation of numerous crystal nuclei. Consequently, during the faster crystallization process, the supersaturated precursor solution exhibits a marked preference for the formation of higher- n value quasi-2D phases, concurrently suppressing the formation of lower- n value phases. , …”

“…Consequently, during the faster crystallization process, the supersaturated precursor solution exhibits a marked preference for the formation of higher-n value quasi- 2D phases, concurrently suppressing the formation of lower-n value phases. 26,27 To scrutinize the influence of TMPO addition and antisolvent treatment on the surface morphology of perovskite films, we have performed atomic force microscopy (AFM) and scanning electron microscopy (SEM) characterization of samples subjected to various conditions. The incorporation of TMPO into the perovskite precursor solution leads to a significant reduction in the root-mean-square (RMS) roughness of the perovskite film, as shown in Figure S1.…”

Self‐Assembled Molecule Doping Enables High‐Efficiency Hole‐Transport‐Layer‐Free Perovskite Light‐Emitting Diodes

“…As shown in Figure 1c, four distinct exciton absorption peaks between 400 and 520 nm that correspond to the n = 1 to 4 phases can be clearly resolved in the undoped sample. [ 27–29 ] While with the increase of Me‐4PACz concentration, the relative intensity of the four exciton absorption peaks decreased significantly, and the uniform phase distribution was achieved when the concentration reached 4 mg/ml. The suppressed formation of small‐n phases with Me‐4PACz is also confirmed by the X‐ray diffraction (XRD) patterns, where a peak at 5.4° corresponding to the (002) plane for n = 1 phase is significantly inhibited with the addition of 4 mg ml −1 Me‐4PACz, as shown in Figure S2 (Supporting Information).…”

Nanoimprinted Quasi‐2D Perovskites toward High‐Performance Polarization‐Sensitive Photodetectors

“…In recent years, halide perovskites have found promising applications in polarization-sensitive photodetection due to their excellent optoelectronic properties such as high absorption coefficient, [5] long carrier diffusion length, [6] and tunable band gap. [7][8][9][10] In general, the polarizationsensitive perovskite photodetectors (PSP-PDs) can be made by using perovskites with intrinsically anisotropic crystal structures or by combining perovskites with other materials that have anisotropic crystal structures into heterojunctions; [11][12][13][14] or by forming perovskites with anisotropic morphology, especially nanowires (NWs). [15][16][17] Despite these achievements, preparing large-scale and high-quality perovskite crystals with an anisotropic crystal structure is challenging and time-consuming.…”