Influence of Surface Chemistry on the Binding and Electronic Coupling of CdSe Quantum Dots to Single Crystal TiO₂Surfaces

Citations Over TimeTop 10% of 2010 papers

Abstract

Sensitization of mesoporous nanocrystalline TiO(2) solar cells with quantum confined semiconductor nanocrystals (QDs) has some advantages over organic dyes or inorganic complex sensitizers, yet the reported efficiencies of laboratory devices are not currently competitive with those of dye sensitized cells. Several methods previously utilized to bind CdSe QDs to mesoporous TiO(2) films were investigated using low index faces of both anatase and rutile TiO(2) polytypes as model systems. The in situ ligand exchange method, where 3-mercaptopropionic acid (MPA) covered TiO(2) crystal surfaces are treated with trioctylphosphine (TOP)/trioctylphosphine oxide (TOPO) (TOP/TOPO)-capped CdSe QDs, resulted in very irreproducible and usually low sensitized photocurrents. The ex situ ligand exchange method, whereby MPA-capped QDs are synthesized and directly adsorbed onto bare TiO(2) single crystals, resulted in both reproducible sensitized photocurrents and surface coverages that are verified with atomic force microscopy (AFM). Purification of the nanocrystals and adjustment of the pH of the sensitization solution to >10.2 was found to prevent QD agglomeration and takes advantage of the dual chemical functionality of MPA to directly link the QDs to the TiO(2) surface. The spectral response of the incident photon to current efficiencies of CdSe QDs was directly compared to the commonly used sensitizer cis-di(thiocyanato)-bis(4,4;-dicarboxy-2,2'-bipyridine)ruthenium(II) (N3) on the same single crystals.

Related Papers

• → The solvent effect on luminescent properties of cadmium selenide quantum dots(2015)13 cited
• → Molecular dynamics simulation of the structure of mixed ligand shells stabilizing cadmium selenide nanoparticle surfaces with different curvatures(2016)8 cited
• → Computer simulation of ligand shells of colloidal cadmium selenide quantum dots(2016)7 cited
• → Dependence of Luminescence Efficiency of CdSe Quantum Dots on Chemical Environments(2008)9 cited
• → An unusual fluorescence evolution of cadmium selenide (CdSe) nanoparticles generated from a cadmium oxide/trioctylphosphine selenide/trioctylphosphine heterogeneous system(2009)5 cited