title: Improved performance of nanowire-quantum-dot-polymer solar cells by chemical treatment of the quantum dot with ligand and solvent materials.
abstract: We report a nanowire-quantum-dot-polymer solar cell consisting of a chemically treated CdSe quantum dot film deposited on n-type ZnO nanowires. The electron and hole collecting contacts are a fluorine-doped tin-oxide/zinc oxide layer and a P3HT/Au layer. This device architecture allows for enhanced light absorption and an efficient collection of photogenerated carriers. A detailed analysis of the chemical treatment of the quantum dots, their deposition, and the necessary annealing processes are discussed. We find that the surface treatment of CdSe quantum dots with pyridine, and the use of 1,2-ethanedithiol (EDT) ligands, critically improves the device performance. Annealing at 380 °C for 2 h is found to cause a structural conversion of the CdSe from its initial isolated quantum dot arrangement into a polycrystalline film with excellent surface conformality, thereby resulting in a further enhancement of device performance. Moreover, long-term annealing of 24 h leads to additional increases in device efficiency. Our best conversion efficiency reached for this type of cell is 3.4% under 85 mW cm(-2) illumination.
authors.affiliation: Department of Physics, Portland State University, Portland, OR 97201, USA. nadaraja@pdx.edu
authors.forename: A
authors.initials: A
authors.lastname: Nadarajah
authors.forename: T
authors.initials: T
authors.lastname: Smith
authors.forename: R
authors.initials: R
authors.lastname: Könenkamp
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D011211:Electric Power Supplies; D004566:Electrodes; D004867:Equipment Design; D008024:Ligands; D008623:Mercaptoethanol / Q000031:analogs & derivatives / Q000737:chemistry; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D011108:Polymers / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D012993:Solar Energy; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D008024:Ligands; D011108:Polymers; D011725:Pyridines; D018036:Selenium Compounds; D008623:Mercaptoethanol; C031854:1,2-ethanedithiol; C058667:cadmium selenide; C023666:pyridine; D015034:Zinc Oxide