Spectrally Stable and Efficient Pure Red CsPbI₃ Quantum Dot Light-Emitting Diodes Enabled by Sequential Ligand Post-Treatment Strategy

Abstract

Metal halide perovskites are promising semiconductors for next-generation light-emitting diodes (LEDs) due to their high luminance, excellent color purity, and handily tunable band gap. However, it remains a great challenge to develop perovskite LEDs (PeLEDs) with pure red emission at the wavelength of 630 nm. Herein, we report a spectrally stable and efficient pure red PeLED by employing sequential ligand posttreated CsPbI 3 quantum dots (QDs). The synthesized CsPbI 3 QDs with a size of ∼5 nm are treated in sequential steps using the ligands of 1-hydroxy-3-phenylpropan-2-aminium iodide (HPAI) and tributylsulfonium iodide (TBSI), respectively. The CsPbI 3 QD films exhibit improved optoelectronic properties, which enables the fabrication of a pure red PeLED with a peak external quantum efficiency (EQE) of 6.4% and a stable EL emission centered at the wavelength of 630 nm. Our reported sequential ligand posttreatment strategy opens a new route to improve the stability and efficiency of PeLEDs based on QDs.

Ultrastable 0D Organic Zinc Halides with Highly Efficient Blue Light Emissions

“…Therefore, 0D perovskites incline to display intrinsic lower‐energy broadband light emissions with large Stokes‐shifts, which are different from the narrow emission bands of 3D APbX 3 PQDs. [ 18–22 ] As a result, lower‐energy green, yellow, and red light emissions are easily realized in 0D halide perovskites, but higher‐energy blue light emission remains extremely challenging, especially in pure‐blue spectral region (460–480 nm). [ 23–26 ] Simultaneously considering the biological toxicity of Pb 2+ ion and lower PLQY of blue emitting perovskite, it is greatly significant and stringent to design lead‐free 0D perovskites comprising environment‐friendly metals as highly efficient blue emitters to achieve balanced development of three primary‐color in high‐definition display and lighting devices.…”

Ultra‐Thermostability of Spatially Confined and Fully Protected Perovskite Nanocrystals by In Situ Crystallization

“…Therefore, various strategies have been proposed to improve the stability of CsPbX 3 QDs in recent years. Post surface treatment of perovskite QDs have been frequently applied, during which various surface protection layers, including ligands, [10][11][12][13] polymer matrix, [14][15][16][17] and oxides, [8,9,[18][19][20][21] are introduced to the surface of quantum dots to form a surface passivation layer. Progress in terms of enhanced stability of perovskite has been reported in the literature.…”

Recent progress of single-halide perovskite nanocrystals for advanced displays

“…111 Currently, a pure red PeLED based on CsPbI 3 QDs with a stable EL emission centered at a wavelength of 630 nm has been realized. 34 The synthesized QDs with a size of about 5 nm are post-treated in sequential steps using two types of ligand (Fig. 9a–c), and exhibited near 100% PLQY, enhanced carrier transport and improved phase stability.…”

“…29–32 Recently, studies have attempted to tune the bandgaps via quantum confinement effects or cation alloying/doping in pure bromide (iodide)-based LHP NCs, which can approach the desired target. 33–35 Despite great progress in PeLEDs based on single-halide perovskite NCs, there are still critical challenges to achieve efficient and stable PeLEDs.…”