Abstract
<title>Abstract</title> <p>The morphology of the active layer plays a decisive role in governing charge generation, transport, and collection in organic solar cells (OSCs). In this work, electrospinning is introduced as an effective strategy to fabricate nanofibrous active layers based on PVDF-TrFE:PCDTBT:PCBM, aiming to improve the structural organization and photovoltaic performance of inverted OSCs. Three active-layer architectures were investigated: a conventional spin-coated PCDTBT: PCBM film, electrospun PCDTBT: PCBM nanofibers, and electrospun ferroelectric PVDF-TrFE:PCDTBT:PCBM composite nanofibers. The structural, optical, dielectric, and charge-transport properties were systematically examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy, photoluminescence (PL), dielectric spectroscopy, AC conductivity (\(\:{\sigma\:}_{ac}\)), dark charge extraction by linearly increasing voltage (dark-CELIV), external quantum efficiency (EQE), and current density-voltage (J-V) measurements. SEM observations confirmed the formation of a uniform interconnected nanofibrous network, while XRD and FTIR analyses demonstrated that electrospinning and PVDF-TrFE incorporation preserved the chemical structure of the active layer without inducing undesirable structural changes. The electrospun composite nanofibers exhibited enhanced optical absorption, pronounced PL quenching, an increased dielectric constant of 3.91, and improved carrier mobility of 6.44 × 10⁻⁴ cm² V⁻¹ s⁻¹, indicating more efficient exciton dissociation and charge transport. Consequently, the photovoltaic performance was significantly enhanced, with the power conversion efficiency (PCE) increasing from 5.86% for the spin-coated PCDTBT: PCBM device to 7.12% for the electrospun PVDF-TrFE:PCDTBT:PCBM nanofiber device, accompanied by increases in both the short-circuit current density and open-circuit voltage. The improved device performance is attributed to the synergistic effect of the electrospun nanofibrous architecture and the ferroelectric characteristics of PVDF-TrFE, which collectively promote light harvesting, charge separation, and carrier transport. These findings demonstrate that electrospun ferroelectric composite nanofibers represent a promising active-layer design strategy for developing high-efficiency organic solar energy conversion devices.</p>