3.3. X-ray diffraction analysis
The XRD pattern of P3HT-96, P3HT-70 and P3HT-58 is shown
in Fig. 2. The P3HT-96 shows strong first peak at 2 = 5.4◦ and two
weak peaks at 2 = 11◦ and 16◦ and are consistent with the reported values [20,21]. The absence of peaks at 2 = 11◦ and 16◦ for P3HT-70 and P3HT-58 indicates that the polymers are amorphous in nature. This is because; regioregular P3HT undergo macromolecular self assembly due to their regular arrangement of side chain resulting well ordered lamellar structures [20]. On the other hand due to head to head and tail to tail coupling of regio-irregular P3HTs, the main chains do not form ordered structure and hence these polymers mostly have amorphous structure [4]. This is also supported by the literature that even P3HT with 80% regioregularity is amorphous in nature [22].