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Electrical Detection of Quantum Dot Hot Electrons Generated via a Mn2+-Enhanced Auger Process

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journal contribution
posted on 2016-12-05, 00:00 authored by Charles J. Barrows, Jeffrey D. Rinehart, Hirokazu Nagaoka, Dane W. deQuilettes, Michael Salvador, Jennifer I. L. Chen, David S. Ginger, Daniel R. Gamelin
An all-solid-state quantum-dot-based photon-to-current conversion device is demonstrated that selectively detects the generation of hot electrons. Photoexcitation of Mn2+-doped CdS quantum dots embedded in the device is followed by efficient picosecond energy transfer to Mn2+ with a long-lived (millisecond) excited-state lifetime. Electrons injected into the QDs under applied bias then capture this energy via Auger de-excitation, generating hot electrons that possess sufficient energy to escape over a ZnS blocking layer, thereby producing current. This electrically detected hot-electron generation is correlated with a quench in the steady-state Mn2+ luminescence and the introduction of a new nonradiative excited-state decay process, consistent with electron-dopant Auger cross-relaxation. The device’s efficiency at detecting hot-electron generation provides a model platform for the study of hot-electron ionization relevant to the development of novel photodetectors and alternative energy-conversion devices.