Effect of silicon-nanoparticle addition on the nanostructure of polythiophene: Fullurene bulk heterojunction solar cells

We investigated the nanostructure change in bulk heterojunction films of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) before and after adding silicon nanoparticles (SiNP) by employing synchrotron radiation grazing incidence-angle X-ray diffraction (GIXD) techniques. The GIXD results showed a gradual reduction of the P3HT (100) diffraction intensity in the out-of-plane (OOP) direction as the SiNP content was increased. Interestingly, a (100) intensity in the in-plane (IP) direction newly appeared when a small amount of SiNP was added, but it faded at higher SiNP contents. In particular, the addition of 2 wt.% SiNP increased the (100) intensity in both the OOP and the IP directions, leading to improved solar cell performance due to enhanced charge transport in the P3HT domains.