The strain regulated physical properties of PbI2/g-C3N4 for potential optoelectronic device.

The van der Waals (vdW) heterostructures of Z-scheme PbI2/g-C3N4 with an indirect bandgap have gained much attention in recent years due to their unique properties and potential applications in various fields. However, the optoelectronic characteristics and strain-modulated effects are not yet fully understood. By considering this, six stacking models of PbI2/g-C3N4 are proposed and the stablest structure is selected for further investigation. The uniaxial and biaxial strains (-10% ~ 10%) regulated band arrangement, charge distribution, optical absorption in the framework of density functional theory (DFT) are systematically explored. The compressive uniaxial strain of -8.55% changes the band type from II→I, and the biaxial strains of -7.12%, -5.25%, 8.91% change the band type in a way of II→I→II→I, acting like the "band-pass filter". The uniaxial strains except -10% compressive strain, and the -6%, -4%, 2%, 4%, 10% biaxial strains will enchance the light absorption of PbI2/g-C3N4. The exerted strains on PbI2/g-C3N4 generate different power conversion efficiency (ηPCE) values ranging from 3.64% to 25.61%, and the maximum ηPCE is generated by -6% biaxial strain. The results of this study will pave the way for the development of new electronic and optoelectronic materials with customized properties in photocatalytic field and optoelectronic devices.