Free Charges Produced by Carrier Multiplication in Strongly Coupled PbSe Quantum Dot Films

• Published in: Nano letters Vol. 11; no. 10; pp. 4485 - 4489
• Main Authors: Aerts, Michiel, Suchand Sandeep, C. S, Gao, Yunan, Savenije, Tom J, Schins, Juleon M, Houtepen, Arjan J, Kinge, Sachin, Siebbeles, Laurens D. A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12-10-2011
• Subjects: Applied sciences; Carriers; Charge carriers; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electron states; Electronics; Exact sciences and technology; Excitons; Excitons and related phenomena; Joining; Materials science; Microwaves; Molecular electronics, nanoelectronics; Multiplication; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Optoelectronic devices; Photons; Physics; Quantum dots; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; multiple exciton generation; charge generation; quantum dot solids; solar cells; Carrier multiplication; Electrical conductivity; Charge carriers; Lead selenides; Quantum dots; Optoelectronic devices; Electron hole pair; Time resolved spectra; Thin films; Free carrier; Time resolution; Excitons; Electric field effects; Nanostructured materials
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl202915p

We show that in films of strongly coupled PbSe quantum dots multiple electron–hole pairs can be efficiently produced by absorption of a single photon (carrier multiplication). Moreover, in these films carrier multiplication leads to the generation of free, highly mobile charge carriers rather than excitons. Using the time-resolved microwave conductivity technique, we observed the production of more than three electron–hole pairs upon absorption of a single highly energetic photon (5.7E g). Free charge carriers produced via carrier multiplication are readily available for use in optoelectronic devices even without employing any complex donor/acceptor architecture or electric fields.