Enhanced performance of organic solar cells through incorporation of MoS2 nanoparticles in bulk heterojunction layer

In this work, MoS2 nanoparticles were incorporated in P3HT:PC61BM bulk heterojunction (BHJ) layers and the effect of their concertation on BHJ morphology and structure, its optical absorption spectra and photovoltaic characteristics of P3HT:PC61BM BHJ solar cells were investigated in detail. MoS2 nanoparticles were deposited by laser ablation of MoS2 powders in chlorobenzene. AFM and optical absorption study indicates that an addition of MoS2 nanoparticles in BHJ results in an improved crystallinity and a decreased defect density. The volt-ampere measurements of BHJ solar cells shows that the increase in the MoS2 concertation up to 0.5 wt% leads to the boost of photovoltaic characteristics and a champion device, based on BHJ with MoS2 nanoparticles at concertation 0.5 wt %, generated the power conversion efficiency about 3%, which 3 times higher than an efficiency of a device based on pristine BHJ. The impedance spectroscopy (IS) technique was used to understand the effect of MoS2 nanoparticles on the charge transport mechanism. IS study revealed that a resistance of the BHJ layer slightly and steadily grows by increasing the concentration of MoS2 nanoparticles, whereas a recombination resistance determining the charge recombination rate increases reaching maximum value at the MoS2 concertation of 0.5 wt %. A further growth in the MoS2 concertation results in a decrease of the recombination resistance indicating an acceleration of charge recombination rate. The influence of conductivity nature of MoS2 nanoparticles and their distribution in the BHJ layer on charge transport mechanism is also discussed.