Enhanced Multiple Exciton Generation in Quasi-One-Dimensional Semiconductors

• Published in: Nano letters Vol. 11; no. 8; pp. 3476 - 3481
• Main Authors: Cunningham, Paul D, Boercker, Janice E, Foos, Edward E, Lumb, Matthew P, Smith, Anthony R, Tischler, Joseph G, Melinger, Joseph S
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 10-08-2011
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Electronics; Energy; Energy management; Exact sciences and technology; Excitation; Excitons and related phenomena; Molecular electronics, nanoelectronics; Nanorods; Nanostructure; Natural energy; Optoelectronic devices; Photons; Photovoltaic cells; Photovoltaic conversion; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductors; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Thresholds; carrier multiplication; Multiple exciton generation; nanorods; nanocrystals; photovoltaic; Solar cells; Semiconductor materials; Lead selenides; Optoelectronic devices; Electron hole pair; Photodetectors; Nanostructures; Photovoltaic cell; Excitons; Photovoltaic cells; Nanorod; Nanostructured materials; Nanocrystal
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl202014a

The creation of a single electron–hole pair (i.e., exciton) per incident photon is a fundamental limitation for current optoelectronic devices including photodetectors and photovoltaic cells. The prospect of multiple exciton generation per incident photon is of great interest to fundamental science and the improvement of solar cell technology. Multiple exciton generation is known to occur in semiconductor nanostructures with increased efficiency and reduced threshold energy compared to their bulk counterparts. Here we report a significant enhancement of multiple exciton generation in PbSe quasi-one-dimensional semiconductors (nanorods) over zero-dimensional nanostructures (nanocrystals), characterized by a 2-fold increase in efficiency and reduction of the threshold energy to (2.23 ± 0.03)E g, which approaches the theoretical limit of 2Eg. Photovoltaic cells based on PbSe nanorods are capable of improved power conversion efficiencies, in particular when operated in conjunction with solar concentrators.