Oxychalcogenides have gained widespread attention as
promising
infrared nonlinear optical (IR-NLO) candidates. However, high-performance
oxychalcogenides have rarely been reported in the ultraviolet (UV)
region owing to the low energy gaps (E
g < 4.0 eV). Herein, two non-centrosymmetric (NCS) oxychalcogenides
with one-dimensional (1D) chain structures and wide E
g (>4.3 eV), namely, AEGeOS2 (AE = Sr and
Ba),
have been discovered by combined experiments and theory calculations
as a new source of UV-NLO materials. Significantly, they exhibit excellent
comprehensive performance comparable to the commercial UV-NLO material
KH2PO4 (KDP), including large phase-matching
ranges (>380 nm), sufficient second harmonic generation intensities
(0.7–1.1 × KDP), high laser-induced damage thresholds
(1.2 × KDP), wide transparent regions (0.26–12.2 μm),
and good thermal stability (up to 1100 K). Moreover, systematic structure–activity
relationship analysis illustrates that the 1D homochiral helical [GeOS2]2– chains composed of heteroanionic [GeS2O2] units make major contribution to the desirable
UV-NLO performance. This work makes the two compounds shine out as
new energy in the UV-NLO field and offers a new perspective for the
exploration of structure-driven functional oxychalcogenides.