Background: The microstructures of P3HT (poly(3-hexyl-thiophene)) in P3HT/PCBM ([6

6]-phenyl C61-butyric acid methyl ester) thin films play a key role in governing the performance of organic solar cells (OSCs) based on these films. Purpose: We aim to study the self-organization of P3HT in the P3HT/PCBM thin films annealed at different temperatures. Methods: Using different incidence angles

information about the microstructures of P3HT at different depths in these films was obtained by synchrotron based grazing incidence X-ray diffraction (GIXRD). Results: It is shown that the crystalline structure of P3HT has been substantially improved by thermal annealing. One dimensional GIXRD clearly indicates that P3HT edge-on structures in the inner layers have been improved with their number increased in comparison with those at the surface and the interface layers. In addition

thermal annealing also helps the formation of P3HT face-on structures in the films

as evidenced by 2 dimensional GIXRD. Conclusion: The improved structures in these films lead to more charge transport channels formed to improve the carrier mobility

which in turn helps the improvement of OSCs. Thus

the present GIXRD results will improve the understanding of annealing effects at different depths of the P3HT/PCBM thin films for enhanced OSCs devices.Cited