Nanoscale study of MoSe2/poly(3-hexylthiophene) bulk heterojunctions for hybrid photovoltaic applications

• The n-type nature of MoSe2 doped with Nb has been revealed by SSRM measurements.
• Mechanically exfoliated MoSe2 mixed with P3HT led to hybrid bulk heterojunction.
• PC-AFM measurements showed a local photo-electric effect at the MoSe2/P3HT interface.

Hybrid solar cells are in sustained development among the photovoltaic (PV) technologies. Molybdenum diselenide (MoSe2) is a promising alternative semiconductor for hybrid PV due to its absorption in the near-infrared spectrum, its good carrier transport and its ability to form 2D structures. Scanning Spreading Resistance Microscopy (SSRM) is used for the electrical characterization of crystalline Nb-doped MoSe2. An n-type nature of doping is demonstrated, with local accumulation of dopants in the crystal when substituting Mo atoms by Nb in a 0.01% stoichiometric ratio. On the basis of the SSRM measurements, a band structure for the probe-sample system is proposed. Blends are also prepared with the p-type semiconducting polymer poly(3-hexylthiophene) (P3HT) and the photo-electrical properties of those Nb-doped MoSe2:P3HT systems are studied at the nanoscale by PhotoConductive-Atomic Force Microscopy (PC-AFM).