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In this work, macro- and nanodiagnostic procedures for working, third-generation photovoltaic devices based on a modified polymer:fullerene (P3HT:PCBM) absorber were conducted using atomic force microscopy (AFM) and impedance spectroscopy (IS) equipment. All experiments were performed both in the dark and under irradiation with a specific light wavelength. Photoactive Kelvin probe force microscopy (p-KPFM) and impedance spectroscopy (p-IS) experiments were conducted on half- and whole-solar cell devices. Based on the p-KPFM measurements, the surface potential (SP) and surface photovoltage (SPV) on top of the active layer at the micro/nanoscale were estimated for various light wavelengths (red, green, blue, and white). For light in the red spectrum range, which was associated with an optical absorption edge and acceptor states that occurred in the band gap of the P3HT material after doping the donor polymer with iodine, the SPV was measured at levels of 183 mV, 199 mV, and 187 mV for the samples with 0%, 5% and 10% iodine doping, respectively. In addition, a macroscale investigation enabling the determination of the electrical parameters of the studied organic solar cells (OSCs) was carried out using p-IS. Based on the data obtained during p-IS experiments, it was possible to propose a series electrical equivalent circuit to define and describe the charge transfer phenomenon in the OSCs. Estimations of data obtained from the fitting of the experimental results of p-IS under white light allowed us to evaluate the average diffusion time of electric charges at 8.15 µs, 16.66 µs, and 24.15 µs as a function of organic layer thickness for the device without doping and with 5% and 10% iodine doping. In this study, we demonstrated that correlating information obtained at the macro- and nanoscale enabled a better understanding of the electrical charge distribution of OSCs for indoor applications. [ABSTRACT FROM AUTHOR]

ABSTRACT: Optical properties of polymer/fullerene blend films upon thermal annealing are investigated by spectroscopic ellipsometry and described consistently within an optical model of the blend film. The optical model developed in this work treats both components, polymer and fullerene, as mixtures of reference materials, that is, their optically ordered and disordered phase. Then, the polymer/fullerene blend layer is also described as a mixture of these two components. In this manner, we extend an existing optical model, which accounts for the optical order within the polymer phases, on cases where the optically ordered PCBM phase occurs, too. Determination of the dielectric functions of all four reference materials allows for a unique quantitative characterization of a polymer/fullerene blend film by assigning to it thickness and the polymer to fullerene volume fraction of its layers as well as corresponding volume fractions of theirs optically ordered and disordered polymer and fullerene phases. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1094–1100 [ABSTRACT FROM AUTHOR]