Biaxial strain enhanced piezoelectric properties in monolayer g-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mrow><mml:msub><mml:mtext>C</mml:mtext><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mtext>N</mml:mtext><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>

Graphite-like carbon nitride (g-C3N4) is considered as a promising candidate for energy materials. In this work, the biaxial strain (?4%–4%) effects on piezoelectric properties of g-C3N4 monolayer are studied by density functional theory (DFT). It found that increasing can reduce elastic coefficient C11-C12, and increases stress e11, which lead to enhanced d11. Compared unstrained one, 4% raise d11 about 330%. From ?4% 4%, induce improved ionic contribution e11 g-C3N4, almost unchanged electronic contribution, different from MoS2 (the reduced contribution). indeed more effective strategy than with increase being only 46%. To prohibit current leakage, material should be semiconductor, always semiconductor in range. Calculated results show gap compressive tensile one. At strain, first second valence bands cross, has important effect transition dipole moment (TDM). Our works provide achieve monolayer, gives useful guidance developing efficient conversion devices.