Direct Photo-Patterning of Efficient and Stable Quantum Dot Light-Emitting Diodes via Light-Triggered, Carbocation-Enabled Ligand Stripping

Abstract

Next generation displays based on quantum dot light-emitting diodes (QLEDs) require robust patterning methods for quantum dot layers. However, existing patterning methods mostly yield QLEDs with performance far inferior to the state-of-the-art individual devices. Here, we report a light-triggered, carbocation-enabled ligand stripping (CELS) approach to pattern QLEDs with high efficiency and stability. During CELS, photogenerated carbocations from triphenylmethyl chlorides remove native ligands of quantum dots, thereby producing patterns at microscale precision. Chloride anions passivate surface defects and endow patterned quantum dots with preserved photoluminescent quantum yields. It works for both cadmium-based and heavy-metal-free quantum dots. CELS-patterned QLEDs show remarkable external quantum efficiencies (19.1%, 17.5%, 12.0% for red, green, blue, respectively) and a long operation lifetime (T 95 at 1000 nits up to 8700 h). Both are among the highest for patterned QLEDs and approach the records for nonpatterned devices, which makes CELS promising for building high-performance QLED displays and related integrated devices.

Direct Optical Lithography of Colloidal InP-Based Quantum Dots with Ligand Pair Treatment

“…The variations in solubility of the light-exposed region are enabled by a small amount of PAG additive (1–2 wt %), which is beneficial for both photoluminescence (PL) down-conversion and electroluminescence (EL) applications. Recently, Fu et al employed PAG-based direct optical lithography to fabricate patterned high-efficiency CdSe-based QD LEDs …”

“…In our previous study, we reported that an addition of 2 wt % PAG can reduce the PLQY of CdSe-based core/shell QDs by ∼30%. Although recent studies have attempted to address this issue, − ,, it has not been completely overcome. In particular, the aforementioned issue is observed to be more critical in the case of InP-based QDs .…”

“…Recently, Fu et al employed PAG-based direct optical lithography to fabricate patterned high-efficiency CdSe-based QD LEDs. 12 However, even a small amount of PAG can cause significant variations in the PLQY of the QDs. In our previous study, 11 we reported that an addition of 2 wt % PAG can reduce the PLQY of CdSe-based core/shell QDs by ∼30%.…”

Recent Advances in Interactive Mechanosensory Electronics with Luminescence/Coloration Outputs for Wearable Applications

“…61−63 As shown in Figure 2d f). 64 In addition, QDs possess excellent stability in ambient conditions, which is conducive to the extension of service life. More recently, perovskite LEDs (PeLEDs) based on metallic halide perovskites (MHPs) have also been thriving in the field of optoelectronics (Figure 2g).…”

“…Therefore, an additional encapsulation procedure is critical for luminescence duration. Apart from OLEDs, quantum dot LEDs (QLEDs) are another powerful display technology in virtue of the high color purity, stability and quantum efficiency of QD emitters. − As shown in Figure d, QDs usually have core–shell structures and their surfaces are passivated by organic ligands, thus facilitating their dispersion in nonpolar solvents and the large-scale production of QLEDs (Figure e–f) . In addition, QDs possess excellent stability in ambient conditions, which is conducive to the extension of service life.…”