title: Quantum junction solar cells.
abstract: Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO(2)); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics.
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Tang
authors.forename: Huan
authors.initials: H
authors.lastname: Liu
authors.forename: David
authors.initials: D
authors.lastname: Zhitomirsky
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Hoogland
authors.forename: Xihua
authors.initials: X
authors.lastname: Wang
authors.forename: Melissa
authors.initials: M
authors.lastname: Furukawa
authors.forename: Larissa
authors.initials: L
authors.lastname: Levina
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent
mesh_terms: D011211:Electric Power Supplies; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008839:Microelectrodes; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D011789:Quantum Theory; D012993:Solar Energy; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D014025:Titanium