Two-Dimensional Optical Waveguides at Telecom Wavelengths Based on Organic Single-Crystal Microsheets of a Charge Transfer Complex

• Published in: The journal of physical chemistry letters 2023-03, Vol.14 (12), p.3047-3056
• Main Authors: Xu, Chao-Fei, Liu, Yan-Ping, Yu, Yue, Meng, Xin-Yue, Zong, Hao, Lv, Qiang, Xia, Xing-Yu, Wang, Xue-Dong, Liao, Liang-Sheng
• Format: Article
• Language: English
• Subjects: Physical Insights into Materials and Molecular Properties
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.3c00417

Organic charge transfer (CT) cocrystals open a new door for the exploitation of low-dimensional near-infrared (NIR) emitters by a convenient self-assembly approach. However, research about the fabrication of sheet-like NIR-emitting microstructures that are significant for structural construction and integrated application is limited by the unidirectional molecular packing mode. Herein, via regulation of the biaxial intermolecular CT interaction, single-crystalline microsheets with remarkable NIR emission from 720 to 960 nm were synthesized via the solution self-assembly process of dithieno­[3,2-b:2′,3′-d]­thiophene and 7,7,8,8-tetracyanoquinodimethane. The expected sheet-like structure is conducive to achieving a two-dimensional (2D) optical waveguide with an ultralow optical loss rate of 0.250 dB/μm at 860 nm. More significantly, these as-prepared organic microsheets with tunable thicknesses (h) from 100 to 1100 nm exhibit thickness-dependent NIR optical transportation performance. These findings could pave the way to a new class of low-dimensional NIR emitters for 2D photonics at telecom wavelengths.