tailieunhanh - Solar Cells New Aspects and Solutions Part 5

Tham khảo tài liệu 'solar cells new aspects and solutions part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Relation Between Nanomorphology and Performance of Polymer-Based Solar Cells 131 is oriented parallel - which is the typically observed P3HT orientation. Upon annealing the as-prepared films at various temperatures the d-spacing along the a-axis of the P3HT crystal was found to remain constant indicating that during the interdiffusion process the PCBM does not interpenetrate between the side chains of the P3HT crystal structure. Mayer et al. 2009 The peak width of the diffraction ring corresponding to the aggregates of PCBM does not change during the interdiffusion process showing that PCBM remains in an amorphous state with aggregates large enough to scatter incident X-rays. Only a small change in the distribution of P3HT crystal orientations was found to be present at various levels of interdiffusion while the intensity of the 200 peak of P3HT increased by nearly a factor of two on annealing at 170 C. It was shown that the interdiffusion process has little effect on the crystalline regions of the P3HT film where the diffusion of PCBM into P3HT occurs within the disordered regions of P3HT. To determine how interdiffusion within this system affects the growth of the P3HT crystallites the P3HT crystallite size along the a-axis for the bilayer films was compared to pure P3HT films heated under similar conditions Fig. 7 f - g . The P3HT crystallite size was estimated using the Scherrer equation and plotted against the fraction of PCBM within the P3HT layer Fig. 7 f . The crystallite size was found to increase with increasing annealing temperature regardless of the level of interdiffusion. The P3HT crystallite size in the bilayer system was found to increase most rapidly during the first 5 min of annealing where the crystallite thickness was approching that for a neat P3HT film heated under similar conditions Fig. 7 g . Solvent effects Postproduction treatment requires a rather well controlled environment it adds an additional fabrication costs to the solar cell .