Synthesis, characterization and band gap tuning of CdSe/ZnSe core/shell quantum dots for photovoltaic applications

We have synthesized the core/shell structure with CdSe as core material and ZnSe as shell material (CdSe/ZnSe) by chemical precipitation method. The structural and optical properties of samples are characterized by Transmission Electron Microscope (TEM), UV-Visible spectroscopy (UV-Vis) and Photoluminescence (PL) Spectroscopy. The optical band gaps of CdSe/ZnSe QDs results at various concentrations and with growth of ZnSe shell shows the red shift and confirms the formation of core/shell structure. The PL spectra study reports the emission peaks for CdSe core ranges from 376.32 nm to 722.83 nm, and for CdSe/ZnSe the emission peaks ranges from 349.87 nm to 774.75 nm. Here, decrease in PL intensity is observed, this is due to decreased electron-hole recombination which is an attribute desired for enhancement of photovoltaic applications. Thus, the core/shell structure and high absorption in visible region may lead to higher efficiency of Quantum Dot Sensitized Solar Cells (QDSSCs).