Published online by Cambridge University Press: 31 January 2011
We report a novel hybrid p-i-n heterojunction solar cell consisting of an undoped CdSe quantum dot film sandwiched between electrodeposited n-type ZnO nanowires on a compact ZnO thin film/FTO and a spin-coated hole-conducting layer. Microscopic studies show the conversion of CdSe quantum dots into conformal and continuous polycrystalline thin film coatings on ZnO nanowires upon annealing in CdCl2/ambient air. The morphology change of the CdSe quantum dot layers then provided excellent charge transfer between the absorber layer and the contiguous layers. The quantum-dot-sensitized ZnO nanostructured solar cells exhibited short-circuit current densities ranging from 5 to 10 mA/cm2 and open-circuit voltages of 0.4–0.6 V when illuminated with an 85 mW/cm2 quartz-halogen spectrum. External quantum efficiencies as high as 55–60% were also achieved.