A new neutral organic material DMPO with ultra-strong second-order nonlinear response and excellent anti-deliquescence

Nonlinear optical (NLO) organic materials with large optical nonlinearity and high stability are highly attractive for wide applications. Herein, a new organic NLO chalcone derivative, 1-(4-methoxy phenyl)-3-(4-ethoxy phenyl)-2-propenyl-1-ketone (DMPO), with an ultra-strong second-order nonlinear response was designed and systematically investigated. The as-designed DMPO was synthesized, and DMPO single crystals with a size of 10 × 5 × 4 mm³ were grown rapidly in only 5 days. The as-grown DMPO crystals formed by neutral organic molecules exhibit high transparency over a wide range of 600–1800 nm, a moderate optical band gap of 2.51 eV, and excellent anti-deliquescence. In particular, the second-harmonic generation response of DMPO reaches 1.86 times that of the benchmark material 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate, revealing the outstanding macroscopic optical nonlinearity of DMPO, as designed. Therefore, DMPO combines several advantages, holding great potential for applications in nonlinear optics.