Topics in Applied Physics Volume 111, 2008, pp 287-319

Photoluminescence: Science and Applications

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Abstract

In the past five years photoluminescence (PL) of SWNTs has gone from discoveryto one of the most actively researched areas, with broad impact on the basic scienceof SWNTs, as well as the promise of applications. The simplest free-carrier models ofperfect semiconducting SWNTs in vacuum predict that they have direct bandgapsand therefore should be efficient light absorbers and emitters. Experimentally,isolating SWNTs from environmental interactions proves crucial to observing thisstrong PL. The Coulomb interaction enhanced by one-dimensional confinementrequires that excitonic models be invoked to understand PL features. Preparedproperly, SWNTs are strong PL emitters, with good quantum yield, showingprincipal PL peaks with characteristic lineshapes and (n,m)-dependent emission andabsorption energies, as well as a rich absorption spectrum. PL has emerged as animportant characterization tool for determining (n,m) and (n,m) distributions,albeit with some limitations. Extrinsic factors, such as chemical environment,temperature, electric and magnetic field, or intrinsic factors, such as phonons, aremanifest in SWNT PL. Possible applications in sensing, biological markers, andoptoelectronics are beginning to emerge from current research in SWNT PL.