Transcending QCD in nanostructured solar cells

Gergely Zimanyi
University of California, Davis (UC Davis)

In solar cells the electrons that absorb high energy photons lose much of their energy by emitting heat. In the competing Multiple Exciton Generation (MEG) relaxation channel, high energy electrons generate more than one excited electrons per photon instead, keeping a higher fraction of the energy in the electronic sector. While MEG is weak in the bulk, it may be stronger in nanoparticles (NPs) because quantum confinement enhances the Coulomb interaction. However, quantum confinement also disadvantageously enhances the gap and makes charge extraction harder. This is QCD: the Quantum Confinement Dilemma. We are searching ways to “Transcend QCD”: to reduce the gap AND to simultaneously enhance MEG rates by: (1) The reconstruction of the NP surface; (2) Designing the shape of the NPs; (3) Using exotic, high pressure phase NP cores; and (4) Judicious choosing the embedding matrices to create Type-II interfaces. We focus on earth abundant materials like Si and Ge. See our website for details:

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