Hybrid solar cells from a blend of ligand-capped HgS nanoparticles and poly(3-hexylthiophene)

Full text: Solution-processed hybrid bulk heterojunction solar cells were fabricated using PVP-capped and HDT-capped HgS nanoparticles as electron acceptor and regioregular P3HT as electron donor. Ligand-capped HgS nanoparticles were synthesized by hydrothermal method and HDT-capped nanoparticles were also obtained by ligand-exchange through suspending PVP-capped HgS nanoparticles in HDT under reflux. Nanoparticles were characterized by XRD, FT-IR and TEM. The devices were prepared on ITO-coated glass substrates in the configuration ITO/PEDOT:PSS/active layer/Pd. In a typical device preparation process, PEDOT:PSS was spin coated over previously cleaned substrates to obtain films of several thicknesses (40-60 nm). PEDOT:PSS films were thermal annealed and then the active layer was spin coated under N2 atmosphere. The palladium cathode was finally evaporated under high vacuum conditions (about 10^-5 mbar) and thermal annealing was performed. Once the devices were encapsulated, optical and electrical properties were investigated. Different conditions were studied: spin coating parameters, proportion of substances and concentration on the blend and thermal annealing conditions. Optical, electrical and morphological properties were investigated through AFM, absorption spectroscopy and photovoltaic device measurements. The I-V characteristics were measured without illumination and under simulated one-sun A.M.1.5 direct illumination (100 mW/cm²). The development of hybrid solar cells using HgS nanoparticles is promising due to the interesting optical and electric properties that they have besides the fact of less production cost and stability of the blends. References: [1] Ch. Liu, Z. Holman, U. Kortshagen, Hybrid Solar Cells from P3HT and Silicon Nanocrystals, Nano Lett., 9 (2009) 449-452. [2] M. Wright, A. Uddin, Organic-Inorganic Hybrid Solar Cells: A Comparative Review, Sol. Energ. Mat. Sol. Cells, 107 (2012) 87-111. (author)