MoS2 / TiO2 nanoparticle composite bulk heterojunction solar cell

We investigate hybrid bulk heterojunction (BHJ) solar cell employing layered transition-metal-dichalcogenide molybdenum disulfide (MoS₂) as photon harvesting layer with titanium dioxide (TiO₂) as electron acceptor and poly 3-hexylthiophene (P3HT) as hole conductor. Micro-Raman spectroscopic measurement confirms that MoS₂ coated on porous TiO₂ film consist nanoflakes of monolayer/few layers in the stack. The semiconducting anatase phase of TiO₂ is confirmed by a signature peak at 146 cm^-1, with two other peaks at 383 cm^-1 and 407 cm^-1 corresponding to MoS₂ in the film. The BHJ solar cell having a stacked structure of ITO/TiO₂/MoS₂/P3HT/Au showed a short circuit current density of 4.7 mA/cm², open circuit voltage of 560 mV, and photoconversion efficiency of 1.3% under an illumination of 100 mW/cm². The external quantum efficiency of the BHJ solar cell confirms that MoS₂ nanoflakes absorb solar photons in a wavelength range of 350 nm ~ 800 nm. Dark current-voltage characteristics of the BHJ solar cell under low and medium forward bias regions suggest that electron recombination at TiO₂/MoS₂/P3HT interfaces limits photovoltaic performance of the device.