630-mV open circuit voltage, 12% efficient n-Si liquid junction

Mary L. Rosenbluth, Charles M. Lieber, Nathan S. Lewis

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Abstract

We report the first experimental observation of a semiconductor/liquid junction whose open circuit voltage Voc is controlled by bulk diffusion/recombination processes. Variation in temperature, minority-carrier diffusion length, and/or in majority-carrier concentration produces changes in the Voc of the n-Si/CH3OH interface in accord with bulk recombination/diffusion theory. Under AM2 irradiation conditions, the extrapolated intercept at 0 K of Voc vs T plots yields activation energies for the dominant recombination process of 1.1-1.2 eV, in accord with the 1.12-eV band gap of Si. A crucial factor in achieving optimum performance of the n-Si/CH3OH interface is assigned to photoelectrochemical oxide formation, which passivates surface recombination sites at the n-Si/CH 3OH interface and minimizes deleterious effects of pinning of the Fermi level at the Si/CH3OH junction. Controlled Si oxide growth, combined with optimization of bulk crystal parameters in accord with diffusion theory, is found to yield improved photoelectrode output parameters, with 12.0±1.5% AM2 efficiencies and AM1 Voc values of 632-640 mV for 0.2-Ω cm Si materials.

Original languageEnglish
Pages (from-to)423-425
Number of pages3
JournalApplied Physics Letters
Volume45
Issue number4
DOIs
Publication statusPublished - Dec 1 1984

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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