Third-order response and improving the photovoltaic efficiency of the copolymer P3HT:PCBM doped with iodine as a solar cell

Z-scan method using a 532 nm laser wavelength was employed to determine the nonlinear refractive index (NORX) of an iodine polymer film. This technique involved a closed aperture that allowed part of the laser beam to pass through and reach the sensitive membrane of the detector. According to the measurements, NORX indicates that the iodine-doped PMMA film exhibits a negative nonlinearity, with n2=-339.14×10-6cm2/W. Furthermore, the value of the enhancement factor greater than one (Wmerit>1) and a thermo-optic coefficient of 10−5, making it a promising material for numerous industrial applications. The effects of the iodine dye on preserving the full brightness of the polymer film over an extended period were also investigated. Beside that a mathematical model was studied using experimental values and found that the color matching functions of the iodine-doped PVP/PMMA films remained stable. A layer of pure P3HT:PCBM was prepared and then doped with different iodine concentrations (0.9 and 1.5 mM). Adding iodine to the P3HT:PCBM layer at a concentration of 1.5 mM increased the dark current by 3 times. The conductance-frequency (G-F) and capacitance-frequency (C-F) measurements were performed in the range of 0 Hz–100 MHz, and then the interface state number due to depletion was determined. The power conversion efficiency (PCE) to be in the range (1.066–1.383).This study demonstrated that the iodine-doped polymer film is a promising material for optoelectronics application such as polymer-dispersed liquid crystals, electrophoretic displays, and X-ray sensors.