Dual Type-II Colloidal Quantum Wells for Efficient Nonlinear Optical Limiting

作者：Junhong Yu, Emek G. Durmusoglu, Yunfei Ren, Wenhui Fang, Yubu Zhou, Linghao Chu, Baiquan Liu, Hilmi Volkan Demir · 发表于：ACS Nano · 年份：2025 · DOI：10.1021/acsnano.5c00391 · 被引用次数：8 · 研究领域：Nonlinear Optical Materials Studies、Optical Coherence Tomography Applications、Ocular and Laser Science Research

Colloidal II–VI nanocrystals have garnered significant research attention in nonlinear optical applications due to their low-cost synthesis, photophysical tunability, and ease of device integration. Herein, we report that dual-type II CdSe/CdTe/CdSe colloidal quantum wells (CQWs) with core/crown/crown structures achieve remarkable nonlinear optical limiting capabilities driven by an exceptionally large nonlinear absorption coefficient. Open aperture Z -scan reveals that these dual-type II CQWs exhibit a third-order nonlinear absorption coefficient of 33.1 cm/GW and an ultralow optical limiting threshold (0.71 GW/cm 2 ), which is superior to that of any other reported colloidal semiconductor nanocrystals while also being comparable to existing two-dimensional (2D) dichalcogenide sheets. Photophysical analysis indicates that such a remarkable nonlinear optical performance in dual-type II CQWs can be primarily ascribed to the efficient excited state absorption (i.e., the sequential two-photon absorption), which benefits from the ultrafast and uniform formation of charge separation states in the dual type-II heterostructures.