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We have developed an artificial intelligence tool, XES Neo, for fitting x-ray emission spectroscopy (XES) data using a genetic algorithm. The Neo package has been applied to extended x-ray absorption fine structure [Terry et al., Appl. Surf. Sci. 547, 149059 (2021)] as well as Nanoindentation data [Burleigh et al., Appl. Surf. Sci. 612, 155734 (2023)] and is in development for x-ray photoelectron spectroscopy data. This package has been expanded to the fitting of XES data by incorporating basic background removal methods (baseline and linear) optimized simultaneously with peak-fitting using the active background approach, as well as the peak shapes Voigt, and an asymmetrical Voigt, known as the Double Lorentzian. The fit parameters are optimized using a robust metaheuristic method, which starts with a population of temporary solutions known as the chromosomes. This population is then evaluated and assigned a fitness score, from which the best solution is then found. Future generations are created through crossover of the best sets of parameters along with some random parameters. Mutation is then done on the new generation using random perturbations to the chromosomal parameters. The population is then evaluated again, and the process continues. The analyzed data presented here are available in the corresponding XESOasis discussion forum (https://xesoasis.org/ai_posted). 

Abstract Combined with polymer ferroelectric dielectrics, organic field‐effect transistors are promising candidates for both electrical and photonic synapses to emulate important functions of biological synapses. In this work two distinct copolymers of poly (vinylidene fluoride) (PVDF) with trifluoroethylene and hexafluoropropylene, PVDF‐TrFE and PVDF‐HFP, respectively, are utilized as ferroelectric dielectrics due to their polarization control and non‐volatile polarization hysteresis. Using a donor–acceptor copolymer as the semiconductor layer, bottom‐gate, top‐contact transistors are fabricated with externally poled and unpoled films of PVDF‐TrFE and PVDF‐HFP where the operating voltages are less than 10 V. On average, poled PVDF‐TrFE FETs show improved characteristics with carrier mobilities > 1 cm²V⁻¹s⁻¹. The individual transistors are evaluated in a system level network for image recognition. The synaptic response of these devices is quantified using key metrics such as the dynamic range and nonlinearity of the analog channel conductance modulation, which are then employed to simulate the neural network behavior. The accuracy of the network in recognizing a set of handwritten digits is used to assess the effectiveness of these devices in neuromorphic architectures. The results are analyzed in terms of the poling condition of the ferroelectric dielectric, the margin of conductance modulation, and the nonlinear weight updates. 

While electrical poling of organic ferroelectrics has been shown to improve device properties, there are challenges in visualizing accompanying structural changes. We observe poling induced changes in ferroelectric domains by applying differential phase contrast (DPC) imaging in the scanning transmission electron microscope, a method that has been used to observe spatial distributions of electromagnetic fields at the atomic scale. In this work, we obtain DPC images from unpoled and electrically poled polyvinylidene fluoride trifluorethylene films and compare their performance in polymer thin film transistors. The vertically poled films show uniform domains throughout the bulk compared to the unpoled film with a significantly higher magnitude of the overall polarization. Thin film transistors comprising a donor–acceptor copolymer as the active semiconductor layer show improved performance with the vertically poled ferroelectric dielectric film compared with the unpoled ferroelectric dielectric film. A poling field of 80–100 MV/m for the dielectric layer yields the best performing transistors; higher than 100 MV/m is seen to degrade the transistor performance. The results are consistent with a reduction in deleterious charge carrier scattering from ferroelectric domain boundaries or interfacial dipoles arising from electrical poling.