Tailoring Cu2−xTe quantum-dot-decorated ZnO nanoparticles for potential solar cell applications

• Novel and convenient route to synthesize Cu2−xTe quantum-dot by SILAR process.
• Growth mechanism of Cu2−xTe QDs based on ion deposition was proposed.
• The optical energy gap, phase formation, and vibration modes were investigated.
• The obtained QDs have potential application for broadband sensitizer of QDSCs.

Cu2−xTe QDs on ZnO nanoparticles were synthesized using a successive ionic layer absorption and reaction technique (SILAR) at room temperature. The as-synthesized QDs which were distributively deposited on ZnO nanoparticles surface were characterized by field emission scanning electron microscope (FE-SEM), X-ray diffraction and high-resolution transmittance microscope (HR-TEM). It revealed that the average diameter of the QDs was ∼2 nm. The synthesized Cu2−xTe QDs were solely orthorhombic Cu1.44Te phase. The growth mechanism was supposed that it based on ions deposition. The energy gap of as-synthesized Cu2−xTe QDs was determined ∼1.1 eV and the smallest energy gap of 0.76 eV was obtained, equal to that of bulk material. Raman spectroscopy and FTIR were also used to study the Cu2−xTe QDs on ZnO nanoparticles. These characteristics suggest a promising implication for a potential broadband sensitizer of QDSCs.