A comparative study on the morphology of P3HT:PCBM solar cells with the addition of FeO nanoparticles by spin and rod coating methods.

Zhang, Wenluan; Nguyen, Ngoc; Murray, Roy; Xin, Jiyuan; Mackay, Michael

Our previous study presented up to 20% power conversion efficiency (PCE) enhancement of poly(3-hexylthiophene):phenyl-C-butyric acid methyl ester (P3HT:PCBM) solar cells under the FeO nanoparticles (NPs) self-assembly (SA) effect by spin coating. FeO NPs (about 11 nm hydrodynamic diameter) form a thin layer at the top interface of the light absorbing active layer, which results in the generation of PCBM rich region improving the charge transport (Zhang et al. Sol Energ Mat Sol C 160:126-133, 2017). In order to investigate the feasibility of this FeO NPs SA effect under large-scale production condition, a smooth rod was implemented to mimic roll-to-roll coating technique and yield active layers having about the same thickness as the spin-coated ones. Small angle neutron scattering and grazing incidence X-ray diffraction were employed finding out similar morphologies of the active layers by these two coating techniques. However, rod-coated solar cell's PCE decreases with the addition of FeO NPs compared with the one without them. This is because PCBM rich region is not created at the top interface of the active layer due to the absence of FeO NPs, which is attributed to the weak convective flow and low diffusion rate. Moreover, in the rod-coated solar cells, the presence of FeO NPs causes decrease in P3HT crystallinity, thus the charge transport and the device performance. Our study confirms the role of spin coating in the FeO NPs SA effect and enables researchers to explore this finding in other polymer nanocomposite systems.

SOLAR cells; IRON oxide nanoparticles; CRYSTAL morphology; SPIN coating; ELECTRIC power conversion; METHYL formate; POLYTHIOPHENES

Journal of Nanoparticle Research, 2017, Vol 19, Issue 9, p1

1388-0764

Academic Journal

10.1007/s11051-017-4016-2