Third-Order Nonlinear Optical Properties of Phenothiazine-Iodine Charge Transfer Complexes in Different Proportions

•Stable charge transfer complexes were synthesised in three different proportions by a simple method.•Charge transfer complex gives an absorption spectrum of charge transfer band in the UV-Visible range.•The synthesised charge transfer complexes possess excellent nonlinear optical properties.•Optical nonlinearity of the complexes varies with electron donor and electron acceptor proportions. The nonlinear optical properties of phenothiazine-iodine (PTZ-I) charge transfer complexes (CTC) in three different proportions were investigated by z-scan set up using Nd: YAG laser at 532 nm wavelength, 7 ns pulse width and 10 Hz repetition rate as excitation source. The interaction between phenothiazine and iodine was analysed using FTIR spectroscopy. The morphological changes after the formation of CTC were observed with the help of scanning electron microscopy and optical microscopy. The CTC system displayed an absorption in the UV-Visible region, which is attributed to the charge transfer between constituents. Optical nonlinearity was observed to be maximum when the molar ratio between phenothiazine and iodine is 1:1, and it strongly depends on the electron donor-acceptor proportion. Optical limiting threshold values of the studied samples are comparable to many reported values. The excellent nonlinear optical properties exhibited by PTZ-I CTC make them promising candidates in nonlinear optical applications.