Synthesis and processing of strong light absorbent iron pyrite quantum dots in polymer matrix for efficiency enhancement of bulk-heterojunction solar cell

• Strong light absorbent pyrite quantum dots with diameter 5 nm are synthesized.
• Photo electrochemical efficiency of 3.62% was achieved from normal 2.32% in devices.
• It allows more flexibility, ballistic transport by using inorganic QDs in BJH solar cells.

Light absorbent FeS2 quantum dots (QDs) with an average size of ~5 nm were synthesized by the colloidal method using a dodecylamine as a solvent and structure directing ligand at 215 °C in a Schlenk flask. X-ray diffraction pattern and UV–vis spectra analysis show a phase pure pyrite with a band gap of 0.99 eV. These QDs were blended in a polymer matrix comprising of poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM, 10 mg:10 mg) in bulk-heterojunction solar cell with loading of 10 wt%, 20 wt%, and 40 wt% of P3HT in order to harness excess light to enhance the efficiency and balance carrier mobility in our quest to devise efficient solar cells. An enhanced efficiency of 3.62% with the 20 wt% of QDs addition was achieved from the normal BHJ device of efficiency 2.32%. However, addition of 40 wt% QDs shows a decreased efficiency of 1.77%. The extended light harvest induced electronic mobility and reduced recombination of electron–hole may contribute to higher efficiencies. The morphology and optoelectronic properties are characterized by TEM, XRD, UV–vis, EQE and I–V curve techniques.