Patterned quantum dot color converters (QDCCs) convert blue light to green and red light at the pixel level, thus having potential applications in combination with micro-LED and OLED. Lithography is a promising method to fabricate the QDCCs, however, it is still a challenge to achieve highly luminescent and stable patterned QD-photoresist (PR) thick films. Herein, a strategy is developed to fabricate high-performance patterned QDCCs using the lithography process. Firstly, the QDs are modified by replacing their native hydrophobic ligands to achieve compatibility with PRs. Then, a new ligand, diphenylphosphine oxide (DPPO), is introduced to remedy surface defects of the modified QDs. Lastly, conventional lithography is adopted to fabricate QDCCs with a pattern size of 50 × 10 µm and a thickness of 8 µm. The passivation with DPPO is critical to the luminescent properties of the QD-PR films. The DPPO substantially increases the PLQYs of the PR-compatible QDs and the QD-PR films, achieving a supreme PLQY of 71.7% for the green QD-PR films. The present work might shed light on improving the performance of patterned QDCCs and accelerate their applications in new types of display technology.
The performance of tin (Sn)-based perovskite light-emitting diodes (PeLEDs) lags behind their lead analogs due to the challenges of Sn 2+ oxidation, defect passivation, and fast crystallization. Herein, the passivation effects of diphenylphosphine oxide (DPPO) derivatives on the fabrication of PEA 2 SnI 4 films are investigated. The DPPO derivatives with hydroxyl group, or including substituent group with the potential to form hydroxyl group, are unfavorable passivators due to their positive effects in accelerating Sn 2+ oxidation. In comparison, amino-functionalized DPPO molecule is an effective additive to enhance the photoluminescence of PEA 2 SnI 4 films due to the effective defect passivation as well as crystallinity improvement. Based on the optimized films, color-stable pure-red PeLEDs are demonstrated with a full width at half maximum of 23 nm at 630 nm, a maximum luminance of 451 cd m −2 , a maximum external quantum efficiency of 3.51%, and a half-lifetime of 13.7 min at 102 cd m −2 . This work opens new prospects on the selection of effective molecular additives for Sn-based perovskites.
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