Cu₂Ge(S_3–<i>x</i>Se_<i>x</i>) Colloidal Nanocrystals: Synthesis, Characterization, and Composition-Dependent Band Gap Engineering

Abstract

A facile solution-phase route was developed to synthesize a family of monodisperse Cu2Ge(S(3-x)Se(x)) alloyed nanocrystals (NCs) with controlled composition across the entire range (0 ≤ x ≤ 3). The band gaps of the resultant NCs can be engineered by tuning the compositions with a nearly linear relationship between them. The band structures of the NCs were studied by cyclic voltammetry and UV-vis absorption spectroscopy. The conducting behavior was revealed to be p-type for these NCs by photoelectrochemical measurements. Their photovoltaic applicability was finally assessed by fabricating solar cells with the Cu2Ge(S2Se) NCs as light harvester and CdS nanorods as electron conducting materials.