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

Abstract

Hole‐transport‐layer‐free (HTL‐free) perovskite light‐emitting diodes (PeLEDs) are attracting increasing research attention because of their simplified device structure, fast preparation process, and high cost effectiveness. However, their much lower external quantum efficiency (EQE) as compared with the conventional p‐i‐n type ones has considerably limited their application prospects. Here, a self‐assembled molecule (SAM) doping strategy is proposed by introducing [4‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl) butyl] phosphonic acid (Me‐4PACz) containing PO functional groups into the perovskite precursor solution and preparing the HTL‐free quasi‐2D perovskite films through the one‐step spin‐coating process. The doped Me‐4PACz molecules can not only accumulate at the ITO/perovskite interface to lower the hole injection barrier, but also extend deep into the perovskite layer to suppress the trap density in perovskite films and regulate the crystallization process for monodispersed phase composition. With the further addition of ethoxylated trimethylolpropane triacrylate small molecule containing CO groups to passivate the defects synergistically with Me‐4PACz, the EQE of the corresponding device is boosted from 1.5% to 16.7% together with a 3.5‐fold increase in operational stability, which is the highest efficiency reported so far for HTL‐free PeLEDs. The results demonstrate that the SAM doping strategy can be a viable and facile way to prepare high‐performance HTL‐free PeLEDs for practical applications.

Reducing Nonradiative Losses of Air‐Processed Perovskite Films via Interface Modification for Bright and Efficient Light Emitting Diodes

“…Based on these results, the energy level diagrams are given in Figure 3e,f, where the energy levels of 1,3,5-tri(1phenyl-1H-ben-zimidazole-2-yl) benzene (TPBi) and LiF/Al are taken from literatures. [36,37] It is clear that the energy level of 2PACz downshifts after PFNBr modification, while the CBM and VBM levels of perovskite shift upward. Such changes in the energy level alignment due to PFNBr modification could help promote the hole injection from the HTL to perovskite and reduce the nonradiative losses at the SAM-perovskite interface, which is beneficial for the performance of perovskite LEDs.…”

Defect passivation engineering of wide-bandgap perovskites for high-performance solar cells

“…Meanwhile, the Me-4PACz substrate can especially improve the photostability of continuous illumination. 93 4.1.2 Low-dimensional perovskites to passivate buried interfaces. Low-dimensional perovskites refer to perovskite materials that have reduced dimensions compared to traditional three-dimensional (3D) perovskites, which show altered crystal structures and unique electronic properties when applied on ITOs before generating traditional 3D perovskites.…”

“…4b illustrates three SAM molecules for PVSCs, among which the 2PACz exhibited the highest efficiency of 20.9% for the Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 solar cells and an efficiency of 23.26% for perovskite/CIGS TSCs. 93 In addition, the methyl-substituted carbazole monolayer named Me-4PACz ([4-(3,6-dimethyl-9 H -carbazol-9-yl)butyl]phosphonicacid) was also used as HTL, which can allow fast hole extraction and minimize non-radiative recombination. Meanwhile, the Me-4PACz substrate can especially improve the photostability of continuous illumination.…”

“…Meanwhile, the Me-4PACz substrate can especially improve the photostability of continuous illumination. 93…”

Efficient and High-Radiance Silicon-Based Perovskite Light-Emitting Diodes through Phase Segregation Control

“…Metal halide perovskites (MHPs) have rapidly advanced as materials for next-generation displays and light sources due to their high photoluminescence quantum yield (PLQY), pure color emission with narrow bandwidths, widely tunable bandgap, and low-temperature solution processability. − With the extensive research during the past few years, perovskite light-emitting diodes (PeLEDs) have achieved an external quantum efficiency (EQE) of over 20% for various colors. − Recently, the integration of perovskite light-emitting materials with a mature silicon platform has emerged as a groundbreaking avenue for advancing optoelectronic technologies. Traditional flat-panel displays, characterized by LED pixels on transparent thin-film transistor back panels, have paved the way for numerous applications.…”