{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T13:04:33Z","timestamp":1781096673817,"version":"3.54.1"},"reference-count":38,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2025,6,26]],"date-time":"2025-06-26T00:00:00Z","timestamp":1750896000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Natural Science Foundation of China","award":["22171076"],"award-info":[{"award-number":["22171076"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>This fundamental understanding of molecular structure\u2013NLO property relationships provides critical design principles for next-generation optical limiting materials, quantum photonic devices, and ultrafast nonlinear optical switches, addressing the growing demand for high-performance organic optoelectronic materials in laser protection and photonic computing applications. In this study, it was observed that selenophene-incorporated fused D-A-D architectures exhibit a remarkable enhancement in two-photon absorption characteristics. By strategically modifying the heteroatomic composition of the Y6-derived fused-ring core, replacing thiophene (BDS) with selenophene (BDSe), the optimized system achieves unprecedented NLO performance. BDSe displays a nonlinear absorption coefficient (\u03b2) of 3.32 \u00d7 10\u221210 m\/W and an effective two-photon absorption cross-section (\u03c3TPA) of 2428.2 GM under 532 nm with ns pulse excitation. Comprehensive characterization combining Z-scan measurements, transient absorption spectroscopy, and DFT calculations reveals that the heavy atom effect of selenium induces enhanced spin\u2013orbit coupling, optimized intramolecular charge transfer dynamics and stabilized excited states, collectively contributing to the superior reverse saturable absorption behavior. It is believed that this molecular engineering strategy establishes critical structure\u2013property relationships for the rational design of organic NLO materials.<\/jats:p>","DOI":"10.3390\/molecules30132748","type":"journal-article","created":{"date-parts":[[2025,6,26]],"date-time":"2025-06-26T05:53:13Z","timestamp":1750917193000},"page":"2748","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Enhanced Nonlinear Optical Absorption in Fused-Ring Aromatic Donor\u2013Acceptor\u2013Donor Core Units of Y6 Derivatives"],"prefix":"10.3390","volume":"30","author":[{"given":"Xingyuan","family":"Wen","sequence":"first","affiliation":[{"name":"School of Environment and Safety Engineering, North University of China, Taiyuan 030051, China"},{"name":"Beijing National Laboratory for Molecular Sciences, Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tianyang","family":"Dong","sequence":"additional","affiliation":[{"name":"Beijing National Laboratory for Molecular Sciences, Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xingzhi","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Physical Science and Technology, Suzhou University of Science and Technology, Suzhou 215009, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiabei","family":"Xu","sequence":"additional","affiliation":[{"name":"School of Physical Science and Technology, Soochow University, Suzhou 215123, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaofeng","family":"Shi","sequence":"additional","affiliation":[{"name":"School of Environment and Safety Engineering, North University of China, Taiyuan 030051, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yinglin","family":"Song","sequence":"additional","affiliation":[{"name":"School of Physical Science and Technology, Soochow University, Suzhou 215123, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7984-6639","authenticated-orcid":false,"given":"Chunru","family":"Wang","sequence":"additional","affiliation":[{"name":"Beijing National Laboratory for Molecular Sciences, Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6480-1697","authenticated-orcid":false,"given":"Li","family":"Jiang","sequence":"additional","affiliation":[{"name":"Beijing National Laboratory for Molecular Sciences, Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1038\/s41586-022-05393-7","article-title":"Ultrathin quantum light source with van der Waals NbOCl2 crystal","volume":"613","author":"Guo","year":"2023","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1186\/s43593-021-00010-y","article-title":"Image encryption using spatial nonlinear optics","volume":"2","author":"Hou","year":"2022","journal-title":"eLight"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"102555","DOI":"10.1016\/j.apmt.2024.102555","article-title":"Germanium-based ternary chalcogenide: An emerging low-dimensional material for nonlinear optics and ultrafast photonics","volume":"42","author":"Hani","year":"2025","journal-title":"Appl. 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