Electrochemiluminescence Tuned by Electron-Hole Recombination from Symmetry-Breaking in Wurtzite ZnSe.

The research of highly active electrochemiluminescence (ECL) materials with low toxicity and good solubility remains a substantial challenge. In this work, we present a synthesis method to prepare soluble wurtzite (WZ) ZnSe nanocrystals (NCs), which exhibit good ECL properties. Using high-angle annular-dark-field imaging together with electron hologram methods, we observe that the WZ ZnSe NCs exhibit an unusual symmetry-breaking phenomenon, where the translational symmetry of the polarized Zn-Se bond is broken. The formation of a symmetry-breaking region leads to an accumulation of charge. The good ECL response originates from the increased efficiency of electron-hole recombination by the excess charge redistribution in WZ ZnSe NCs. This study of the relationship between ECL behavior and the architecture of NCs suggests that careful control over the NC structures of semiconductors can tailor their charge distribution via symmetry breaking, which opens new avenues for the design of novel classes of agents for optoelectronic applications.