All Solution‐Processed High Performance Pure‐Blue Perovskite Quantum‐Dot Light‐Emitting Diodes

Abstract

Solution‐processed light‐emitting diodes (LEDs) show great potential for low‐cost fabrication of large‐area display panels, but the efficient perovskite LEDs (PeLEDs) cannot be achieved by all solution process, because the perovskite emitter is easily destroyed by subsequent solution. In particular, the solution‐processed PeLEDs with blue emission wavelength in 460–470 nm (pure‐blue, meeting Rec. 2020 standards) still is inferior. Here, highly efficient and stable pure‐blue PeLEDs are achieved by all solution process based on colloidal perovskite quantum dots and difunctional ZnO (D‐ZnO) nanocrystals. The D‐ZnO nanocrystals are obtained by a ligand strategy of phenethylammonium bromide, which not only repairs the perovskite surface destroyed by the solvent of the D‐ZnO solution, but also enables the balanced charge injection to suppress Auger recombination. The PeLED presented pure‐blue emitting at 470 nm wavelength, a maximum luminance of 11 100 cd m‐2, and external quantum efficiency of 8.7% (record efficiency for pure‐blue emission). The device also showed a continuous operation half‐lifetime of 35 h at luminance of 100 cd m‐2.

Recent progress of single-halide perovskite nanocrystals for advanced displays

“…Tian et al have achieved highly efficient and stable pure-blue PeLEDs at a 470 nm wavelength based on CsPbBr 3 QDs (∼4.3 nm), which presented a maximum luminance of 11 100 cd m −2 , an EQE of 8.7%, and a continuous operation half-lifetime of 35 h at a luminance of 100 cd m −2 . 118 Apart from the small-sized CsPbBr 3 QDs, the perovskite NPLs or nanowires have recently attracted attention due to their advantages of quantum-confined emission, and benefit for achieving a narrow emission linewidth. [119][120][121] For example, 2D CsPbBr 3 NPLs can self-assemble into bigger cuboid crystals, which have an extraordinarily high PLQY of 91% due to a substantially lower surface trap density (Fig.…”

Manipulating Crystallization Dynamics for Efficient and Spectrally Stable Blue Perovskite Light‐Emitting Diodes

“…[5][6][7][8][9][10][11][12][13][14] By contrast, blue PeLEDs (sky-blue: 480-490 nm; pureblue: 466-480 nm; deep-blue: <466 nm) still lags far behind their other counterparts in terms of electroluminescent (EL) efficiencies and spectral stability. [15][16][17][18][19][20] In order to achieve effective and stable blue EL performance, current efforts mainly take advantage of quantum confinement effect in Br/Cl-mixed perovskite system by employing large organic amine ligands as crystallization spacers. [21][22][23] Although impressive advances have been achieved by this way, there are serious problems remaining to be addressed.…”

Interface Engineering with Quaternary Ammonium-Based Ionic Liquids toward Efficient Blue Perovskite Light-Emitting Diodes

“…Since the first preparation of PeLEDs with green and red emission at room temperature in 2014, great improvement has been achieved in the efficiency of monochromatic PeLEDs. − The highest efficiencies of sky-blue, green, and red PeLEDs reported so far are 14.71, 28.1, and 23%, respectively. The efficiency of blue PeLEDs is still relatively poor, especially in the pure-blue region (460–470 nm), which is essential for display applications, , and the highest efficiency is only 8.7% . Further investigation and improvement are urgently needed in blue region.…”

“…The efficiency of blue PeLEDs is still relatively poor, especially in the pure-blue region (460−470 nm), which is essential for display applications, 14,15 and the highest efficiency is only 8.7%. 16 Further investigation and improve-ment are urgently needed in blue region. In a large number of studies on perovskite optoelectronic devices, the interface between the perovskite active layer and the electron transport layer (ETL) or the hole transport layer (HTL) plays a crucial role in the final device performance.…”