Through Analysis of Thin Films Based on Small-Molecule and Polymer NFA Blends for Photovoltaic Conversion: From Neat Materials to Ternary Systems

Focusing on PM6 as the electron-donating polymer and the non-fullerene acceptors Y12 and PY-IT, this study investigates their chemical, optical, and morphological properties, as well as their compatibility in bulk heterojunction (BHJ) architectures. All materials were characterized in thin-film form using Fourier transform infrared (FTIR), and Raman spectroscopy. Binary blends of PM6:Y12 and PM6:PY-IT, along with the ternary PM6:PY-IT:Y12 system, were dissolved in o-xylene and processed into active layers by blade coating under ambient conditions. Optical properties were analyzed in solution and in thin films, providing insights into light-absorption efficiency and spectral complementarity. Nanoscale morphology and molecular packing were examined using atomic force microscopy (AFM) and grazing-incidence wide-angle X-ray scattering (GIWAXS), revealing correlations between material organization and device performance. The results highlight the importance of optimizing material selection, ink formulation, and film morphology to maximize charge-generation efficiency. Power-conversion efficiencies (PCEs) of 13.95%, 12.04%, and 12.17% were achieved for PM6:Y12, PM6:PY-IT, and PM6:PY-IT:Y12 devices, respectively. The ternary PM6:PY-IT:Y12 system demonstrated performance comparable to PM6:PY-IT, with improved miscibility and nearly aggregate-free morphologies, suggesting potential for further efficiency gains. These findings offer valuable guidance for designing high-performance, sustainable active layers, contributing to the development of next-generation organic photovoltaic technologies.