Reber AC, Chauhan V, Bista D, Khanna SN. Superatomic molecules with internal electric fields for light harvesting.
NANOSCALE 2020;
12:4736-4742. [PMID:
32049078 DOI:
10.1039/c9nr09229c]
[Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Traditional p-n junctions used for photovoltaics require an interface where a light induced electron-hole pair is separated by an electric field. Developing alternative strategies for forming strong internal electric fields for electron-hole pair separation offers the possibility for better performance. We demonstrate that fusing two superatomic clusters with donor/acceptor ligands on opposite sides of the cluster leads to such a strong internal electric field. In two fused metal-chalcogenide Re6S8Cl2(L)4 clusters with donor PMe3 ligands and acceptor CO ligands on the opposite sides of the fused clusters, the electronic levels undergo shifts analogous to band bending in traditional p-n junctions. The fused cluster has a large dipole moment, and an optical spectrum that strongly absorbs excitation above the HOMO-LUMO gap of the fused clusters, but is optically very weak for the lowest energy excitation that can lead to electron-hole pair recombination. This is because the electron is localized on the CO portion of the fused cluster, while the electron-hole pair is localized on the PMe3 side of the cluster. It is shown that the electronic states localized on each side of the cluster can be aligned/misaligned by applying a voltage in different directions, offering diode like characteristics.
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