Photophysics of voltage increase by photoinduced dipole layers in sensitized solar cells

Miri Kazes, Sophia Buhbut, Stella Itzhakov, Ohr Lahad, Arie Zaban, Dan Oron

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Significant overpotentials between the sensitizer and both the electron and hole conductors hamper the performance of sensitized solar cells, leading to a reduced photovoltage. We show that by using properly designed type-II quantum dots (QDs) between the sensitizer and the hole conductor in thin absorber cells, it is possible to increase the open circuit voltage (Voc) by more than 100 mV. This increase is due to the formation of a photoinduced dipole (PID) layer. Photogenerated holes in the type-II QDs are retained in the core for a relatively long time, allowing for the accumulation of a positively charged layer. Negative charges are, in turn, injected and accumulated in the TiO2 anode, creating a dipole moment, which negatively shifts the TiO2 conduction band relative to the electrolyte. We study this phenomenon using a unique TiO2/CdSe/(ZnSe:Te/CdS)/polysulfide system, where the formation of a PID depends on the color of the illumination. The PID concept thus introduces a new design strategy, where the operating parameters of the solar cell can be manipulated separately.

Original languageEnglish
Pages (from-to)2717-2722
Number of pages6
JournalJournal of Physical Chemistry Letters
Issue number15
StatePublished - 7 Aug 2014


  • dipole moment
  • extremely thin absorber solar cells
  • high photovoltage cell
  • quantum-dot-sensitized solar cell
  • solar energy
  • type-II QDs


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