Investigation of dielectric, linear, and nonlinear optical properties of synthesized 2D Ruddlesden-Popper-type halide perovskite

Abstract

Ruddlesden-Popper-type halide perovskites (RPPs) have been widely investigated because of their tunable optical properties. The BA2MAPb2I7 (BA = CH3(CH2)3NH3 and MA = CH3NH3) powder is synthesized by a chemical solution-based method at low temperature and deposited on a glass substrate by spin coating technique. The optical transmission, reflection, and absorption investigations are conducted to determine the optical constants of the nano-powder and thin film of BA2MAPb2I7. The obtained results reveal that the optical band gap energy of BA2MAPb2I7 thin film and BA2MAPb2I7 nanoparticles are ∼ 1.95 and ∼ 2.02 eV, which is close to the photoluminescence (PL) peak at around 2.15 eV (576 nm). The optical indexes such as n, k, ε1, and ε2 are assessed based on reflectance spectra data and the Kramers-Kronig (KK) method. Moreover, the third-order nonlinear optical (NLO) characteristics, including nonlinear absorption coefficient (β), nonlinear refractive index (n2), third-order susceptibility (χ(3)) and second-order hyperpolarizability (γ) are investigated at different laser power. The positive signs of the n2 and β reveal that the BA2MAPb2I7 thin film exhibits self-focusing and saturable absorption (SA) properties due to thermal nonlinearity under the continuous wave (CW) laser regime. The magnitude of χ3 is from 20.275 ×10-2 to 29.908 ×10-2esu and the value of γ is from 19.633 ×10-27 to 28.961 ×10-27esu. The superior NLO responses of BA2MAPb2I7 thin-film open the path for the future design and synthesis of desirable and distinct materials for optoelectronic devices.