Large exciton binding energy, superior mechanical flexibility, and ultra-low lattice thermal conductivity in BiI₃ monolayer

The exciton binding energy, mechanical properties, and lattice thermal conductivity of monolayer BiI3are investigated on the basis of first principle calculation. The excitation energy of monolayer BiI3is predicted to be 1.02 eV, which is larger than that of bulk BiI3(0.224 eV). This condition is due to the reduced dielectric screening in systems. The monolayer can withstand biaxial tensile strain up to 30% with ideal tensile strength of 2.60...