Direct Photolithography of Perovskite Nanocrystals via 365 nm UV-Induced Ligand Cross-Linking

초록

Perovskite nanocrystals (PeNCs) exhibit narrow emission line widths and high photoluminescence quantum yields, making them promising for next-generation microdisplays. However, their weak ionic bonding and vulnerability to polar chemicals limit their compatibility with conventional photolithography. Herein, we report an i-line (365 nm)-enabled direct photolithography of PeNCs using benzophenone (BP)-based additive-type light-induced ligand cross-linkers (LiXers). These LiXers generate solubility contrast in PeNC films without requiring polar photoresists or harsh developers. Two LiXers containing dual BP moieties-2-S-BP-LiXer and 2-NS-BP-LiXer-were systematically designed by introducing electron-donating groups to enhance their spectral overlap with i-line irradiation. Time-dependent density functional theory calculations and UV-Vis spectroscopy confirmed a substantially higher molar extinction coefficient for 2-NS-BP-LiXer at 365 nm. Consequently, green CsPbBr3 PeNC films incorporating 2-NS-BP-LiXer achieved robust cross-linking with a low i-line dose of 1.2 J cm(-2), attaining a film thickness retention ratio above 0.85, whereas PeNC films incorporating 2-S-BP-LiXer required >5.4 J cm(-2) to reach comparable resistance. Under the optimized conditions (10 wt % LiXer, 1.2 J cm(-2)), high-resolution PeNC patterns with minimum feature sizes of 2 mu m were realized while preserving similar to 88% of the original PL intensity without the need for posthalide recovery. This work establishes a mild, industry-relevant i-line direct photolithography strategy that enables efficient ligand cross-linking while minimizing photodamage in PeNCs, providing a practical route toward high-resolution multicolored perovskite microdisplays.

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