Solution-phase synthesis of SnSe nanocrystals for use in solar cells.

Nanocrystals of phase-pure tin(II) selenide (SnSe) were synthesized via a solution-phase route employing stoichiometric amounts of di-tert-butyl diselenide as a novel and facile selenium source. The direct band gap of the resulting nanocrystals (E(g) = 1.71 eV) is significantly blue-shifted relative to the bulk value (E(g) = 1.30 eV), a likely consequence of quantum confinement resulting from the relatively small average diameter of the nanocrystals (mu(D) < 20 nm). Preliminary solar cell devices incorporating SnSe nanocrystals into a poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] matrix demonstrate a significant enhancement in quantum efficiency and short-circuit current density, suggesting that this earth-abundant material could be a valuable component in future photovoltaic devices.