La Doping of CdS for Enhanced CdS/CdSe Quantum Dot Cosensitized Solar Cells

CdS/CdSe system of quantum dot cosensitized solar cells (QDCSCs) is one of the most attractive structures for high-efficiency due to its effect of level adjusting. However, the stepwise structure formed between levels of CdS and CdSe has a limitation for enhancing the efficiencies. Metal ions doping in quantum dots have emerged as a common way for changing the Fermi level, band gap, and conductance. Here we report an innovative concept for the rare earth materials La-doped of the CdS layer in the CdS/CdSe QDCSCs by means of the successive ionic layer adsorption and reaction ( SILAR). Then we tested that La doped quantum dots can help more electrons accumulate in CdS film, which makes the Fermi level shift up and forma stepped structure. This method leads to enhanced absorption intensity, obviously increasing current density in CdS/CdSe QDCSCs. Our research is a new exploration for improving efficiencies of quantum dot sensitized solar cells.