Third-order nonlinear optical properties of CsPbCl3 and CsPbBr3 perovskite quantum dots: Effects of particle size and surface traps

Particle size and surface trap effects on the third-order nonlinear optical (NLO) properties of CsPbCl3 and CsPbBr3 perovskite quantum dots (PQD) have been investigated using a femtosecond (fs) z-scan experiment. Firstly, optical, morphological, and structural characterizations of the synthesized PQDs were performed using linear absorption and photoluminescence (PL) spectra, XRD, and TEM methods. Next, NLO properties of CsPbCl3 and CsPbBr3 PQDs were studied at the operating wavelength of 800 nm and 3.564 × 1011 W/cm2 laser intensity. The nonlinear absorption coefficient (β), the nonlinear refraction coefficient (γ), and the third-order susceptibilities (χ(3)) values for both sample types were calculated to be on the order of 10−11 m/W, 10−17 m2/W, and 10−11 esu, respectively. The effects of particle size and surface trap sites on the nonlinear properties of the PQDs were studied thoroughly. γ, χ(3), and the unitless nonlinear figure of merits (FOM) parameters were realized to be proportional to the particle size for both types of materials. In addition, these parameters were improved by decreasing the surface trap sites in the PQDs. These results strongly indicate the significant potential of CsPbCl3 and CsPbBr3 PQDs for numerous nonlinear applications.