Yin–Yang Complementarity Strategy Achieving Giant Optical Anisotropy in a Metal-free Birefringent Material C(NH₂)₃(HC₄O₄)

Abstract

The Yin−Yang complementarity strategy was first proposed to successfully develop a superior metal-free birefringent material C(NH 2 ) 3 (HC 4 O 4 ), which was fabricated by two kinds of planar π-conjugated units containing triangle [C(NH 2 ) 3 ] + cations and square [HC 4 O 4 ] − anions. C(NH 2 ) 3 (HC 4 O 4 ) features a giant birefringence (0.313@546 nm), which is significantly enhanced compared to the commercially available birefringent materials.

SbHPO3F: 2D van der Waals Layered Phosphite Exhibiting Large Birefringence

“…It is well-known that groups with planar π-conjugated configurations, such as (BO 3 ) 3– , , (CO 3 ) 2– , , (NO 3 ) − , , (C 3 N 3 O 3 ) 3– , and [C­(NH 2 ) 3 ] + , , have been considered as favorable candidates to design novel optical materials in the UV or deep-UV region. In the case of Ca­(BO 2 ) 2 , one-dimensional (1D) [BO 2 ] ∞ chains formed by (BO 3 ) 3– planar groups exist in the structure, which shows the largest birefringence (0.247@193 nm) in all reported materials in deep-UV region.…”