The College of Education for Pure Sciences, Department of Physics, organized a scientific lecture on "Studying the Effect of the Donor-Substitute Mixing Ratio on the Performance of the Active Layer in Organic Solar Cells." The lecture, presented by graduate student Noor Al-Huda Hussein Ali, included the preparation of various ratios of P3HT:ICxA thin films of type BHJ to determine the effect of the fullerene ratio on the optical and electrical properties of the active layer. Six donor ratios were prepared: 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, and 1:2. Atomic microwave fluorescence (AFM) images were taken to examine the surface characteristics, revealing that the average roughness ranged between 2 and 4 nm for all samples. Optical measurements confirmed that the 1:1.2 mixing ratio yielded the highest optical response compared to the other samples. In all samples, the absorption coefficient (α > 10⁴ cm⁻¹) indicated direct electron transport in the active layer. Electrical measurements of the samples showed that S4 (1:1.2) was the best-performing sample, exhibiting increases of 2, 3, 1.8, 3.8, and 2.9 times compared to S1, S2, S3, S5, and S6, respectively, under illumination conditions. Electrical measurements, as a function of sample temperature, were conducted in the range of 25–65 °C under both illumination and darkness conditions. The active photovoltaic layer, P3HT:ICxA, generated relatively similar current values ​​in both the heating and cooling cycles, indicating that the active layer's surface properties were optimized and maintained throughout the heating process. Therefore, this study suggests that the active layer with a mixing ratio of S4 (1:1.2) represents the optimal model for solar cell fabrication

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