Characterization and polymerization of thienylphenyl and selenylphenyl amines and their interaction with CdSe quantum dots.

Hybrid quantum-dot-sensitized solar cells show promising novel optoelectronic properties. An adequate design of such cells requires a deep understanding of the characteristics of each component, including their interactions. In this context, the electrochemical properties of two different hole-transporting materials (HTMs) and their chemical interactions with trioctylphosphine-capped CdSe quantum dots are investigated to evaluate their potential use in hybrid quantum-dot-sensitized solar cells. Tris[4-(thien-2-yl)phenyl]amine (TTPA) and tris[4-(selen-2-yl)phenyl]amine (TSePA) are studied in the solid state as thin films deposited on a conducting substrate. Spectroelectrochemical studies evidence both solid-state electropolymerization and doping. Upon addition of TSePA or partially polymerized TTPA to a colloidal solution of trioctylphosphine-capped CdSe quantum dots, the steady-state photoluminescence is quenched. This suggests that the quantum dots and the HTM strongly interact, probably through an excited-state charge-transfer mechanism. The combination of all these pieces of information indicates that polymerized TTPA and TSePA are potential candidates as HTMs for hybrid quantum-dot-sensitized solar cells.