A Second‐Order Nonlinear Optical Material Consisting of Two π‐Conjugated Groups
Minjuan Li, Ziyi Wang, Belal Ahmed, Yanqiang Li, Han Wang, Yipeng Song, Xianyu Song, Xiaojun Kuang, Junhua Luo, Sangen Zhao
Abstract
Abstract This work reports a new second‐order nonlinear optical (NLO) material [C(NH 2 ) 3 ] 3 C 3 N 3 S 3 (GU 3 TMT), consisting of π‐conjugated planar (C 3 N 3 S 3 ) 3− and triangular [C(NH 2 ) 3 ] + groups. Interestingly, GU 3 TMT exhibits a large NLO response (2.0×KH 2 PO 4 ) and moderate birefringence 0.067 at wavelength 550 nm, even though (C 3 N 3 S 3 ) 3− and [C(NH 2 ) 3 ] + do not exhibit the most favorable arrangement in the structure of GU 3 TMT. First‐principles calculations suggest that NLO properties mainly originate from the highly π‐conjugated (C 3 N 3 S 3 ) 3− rings, and the π‐conjugated [C(NH 2 ) 3 ] + triangles contribute much less to the overall NLO response. This work will inspire new thoughts with in‐depth on the role of π‐conjugated groups in NLO crystals.