Structural, optical and electrical investigation of plasma-treated PANI nanostructures for solar cell application

Polyaniline (PANI) has emerged as one of the most important conducting polymers in optoelectronic and photovoltaic (PV) devices because of its excellent environmental stability, high electrical conductivity, and tunable optical properties. For examining the impact of plasma processing on morphological, structural, optical, electrical, and PV properties of PANI nanostructures, they are created and altered utilizing plasma treatment for varying exposure times. A total of three samples has been analyzed: PANI treated with plasma for one minute, PANI as-prepared, and PANI treated with plasma for two minutes. Following plasma treatment, X-ray diffraction (XRD) investigation showed improved structural ordering and crystallinity, with distinctive diffraction peaks seen at roughly 2θ = 20°, 25°, and 45°, that correspond to (020), (200), and (220) planes, respectively. FESEM and AFM analyses showed significant surface evolution, accompanied by an increase in average roughness (Ra) from 18.4 nm for the untreated sample to 24.9 nm and 31.6 nm for the 1 min and 2 min plasma-treated samples, respectively. FTIR spectra confirmed the preservation of the characteristic PANI structure with enhanced conjugation and molecular ordering after plasma exposure. UV–Visible analysis demonstrated improved optical transmittance and a gradual reduction in optical band gap from 3.18 eV (as-prepared) to 3.05 eV and 2.91 eV for the 1 min and 2 min treated samples, respectively. Electrical conductivity increased significantly from 1.82 S·cm⁻¹ to 3.46 S·cm⁻¹ and 5.71 S·cm⁻¹ after 1 min and 2 min plasma treatment, respectively. Consequently, the photovoltaic performance improved substantially, with the power conversion efficiency increasing from 1.84% for the untreated film to 2.76% and 4.12% for the 1 min and 2 min plasma-treated samples, respectively. These findings demonstrate that plasma treatment is simple, cost-effective, and environmentally friendly approach for enhancing the performance regarding PANI nanostructures for solar energy conversion applications.