Superstructures of PbS nanocrystals in a conjugated polymer and the aligning role of oxidation

Abstract

We present a method to directly align PbS nanocrystals in micron-sized superstructures within a conjugated polymer. First, lead sulfide nanocrystals are directly synthesized in a MEH-PPV suspension via a single pot, surfactant-free method. Post-synthesis precipitation of the composite solution involving mild oxidation of the nanocrystals results in the formation of nanocrystal-polymer and nanocrystal-oxide superstructures. Detailed TEM is used to study the crystallographic nature of these structures and the roles of polymer and lead sulfate. An epitaxial relationship between lead sulfide and lead sulfate at the nanoscale is shown, giving insight into the oxidation rates of the PbS nanocrystals' facets.

Preparation and Characterization of Nanocrystalline PbS Thin Films Produced by Chemical Bath Deposition

“…Some clusters are seen on the film surface, and large particles protrude from the surfaces of the PbS thin film. The formation of these grains on the PbS films surface is also observed in other works [11,12].…”

Fine dispersion and self-assembly of ZnO nanoparticles driven by P3HT-b-PEO diblocks for improvement of hybrid solar cells performance

“…[7][8][9][10] However, the conjugated polymers and inorganic nanocrystals are chemically incompatible and tend to form uncontrolled macrophase separation, which impedes the photo-induced electron transfer and charge transport and thus reduces the efficiency of the devices. Extensive efforts have been devoted to optimizing the morphology of the hybrid BHJ materials, including the surface modification of inorganic nanocrystals, [1][2][3]6,[11][12][13] in situ growth of inorganic nanocrystals in conjugated polymer matrices [14][15][16][17] and functionalization of conjugated polymers. 5 Meanwhile, the phase-separated structure observed in such blend films is assumed to be thermodynamically unstable due to the nature of polymer/ inorganic nanoparticles blend, and it is difficult to control the size and orientation of each domain.…”

Routes to Nanostructured Inorganic Materials with Potential for Solar Energy Applications

“…The introduction of stabilizers has an influence on the chemical and physical properties of the particles. The embedding of PbS in polymers to form a nanocomposite structure has been extensively reported. − The growth of PbS in conducting polymers without surfactants allows effective charge transfer between the polymer and nanocrystal in photovoltaic devices. − Rodlike structures are preferred as they act as large surface area electron acceptors and provide continuous conduction pathways for electrons in a bulk heterojunction.…”