Confinement π‐Conjugated Moiety Tailoring to Achieve Record Deep‐UV Nonlinearity in Sulfates

Abstract

ABSTRACT The development of deep ultraviolet nonlinear optical (DUV NLO) materials with simultaneous high performance across multiple properties remains a significant challenge. Key properties, such as a short UV cutoff edge, strong second‐harmonic generation (SHG) response, and suitable birefringence, are often mutually constrained. This study introduces a novel “Three Birds with One Stone” strategy, utilizing a confined π‐conjugated functional group, [OOCCH(NH 3 )CH 2 SO 3 ] − , integrated into the sulfate framework. The approach enhances both polarizability anisotropy and hyperpolarizability while preserving the large band gap inherent to sulfates. This strategy achieves a breakthrough in balancing key performance metrics. Using this new design, we successfully synthesized a novel DUV NLO sulfonate, Li[OOCCH(NH 3 )CH 2 SO 3 ] (LCNS), which demonstrates excellent optical properties, including a short UV cutoff edge (177 nm), a record SHG response (4.5 × KDP), and exceptional birefringence (0.090@589 nm) among DUV NLO sulfonates. This work not only provides a promising candidate for DUV NLO applications but also introduces an innovative strategy for the development of advanced DUV NLO materials.