TUAN HUNG NGUYENZhang, KunyanKunyanZhangvan Thanh, VuongVuongvan ThanhGuo, YunfanYunfanGuoPuretzky, Alexander A.Alexander A.PuretzkyGeohegan, David B.David B.GeoheganKong, JingJingKongHuang, ShengxiShengxiHuangSaito, RiichiroRiichiroSaito2025-09-242025-09-242023https://www.scopus.com/inward/record.uri?eid=2-s2.0-85171758788&doi=10.1021%2Facsnano.3c04436&partnerID=40&md5=a435cecf136fae4b9b58d5694dc2ad6fhttps://scholars.lib.ntu.edu.tw/handle/123456789/732297Nonlinear optical responses in second harmonic generation (SHG) of van der Waals heterobilayers, Janus MoSSe/MoS<inf>2</inf>, are theoretically optimized as a function of strain and stacking order by adopting an exchange-correlation hybrid functional and a real-time approach in first-principles calculation. We find that the calculated nonlinear susceptibility, χ(2), in AA stacking (550 pm/V) becomes three times as large as AB stacking (170 pm/V) due to the broken inversion symmetry in the AA stacking. The present theoretical prediction is compared with the observed SHG spectra of Janus MoSSe/MoS<inf>2</inf> heterobilayers, in which the peak SHG intensity of AA stacking becomes four times as large as AB stacking. Furthermore, a relatively large, two-dimensional strain (4%) that breaks the C<inf>3v</inf> point group symmetry of the MoSSe/MoS<inf>2</inf>, enhances calculated χ(2) values for both AA (900 pm/V) and AB (300 pm/V) stackings 1.6 times as large as that without strain.2d Janus HeterobilayersFirst-principles CalculationsSecond-harmonic GenerationStacking EffectStrain EngineeringTime-dependent Density-functional TheoryDensity Functional TheoryNonlinear OpticsOptical CorrelationVan Der Waals Forces2d Janus HeterobilayerExchange CorrelationsFirst Principle CalculationsNonlinear Optical ResponseStacking EffectStacking OrderStackingsStrain EngineeringTime Dependent Density Functional TheoryVan Der WaalHarmonic GenerationArticleDensity Functional TheoryPredictionjournal article10.1021/acsnano.3c044362-s2.0-85171758788