Photo-induced dipoles: A new method to convert photons into photovoltage in quantum dot sensitized solar cells

Sophia Buhbut, Stella Itzhakov, Idan Hod, Dan Oron, Arie Zaban

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

A high photovoltage is an essential ingredient for the construction of a high-efficiency quantum dot sensitized solar cell (QDSSC). In this paper we present a novel configuration of QDSSC which incorporates the photoinduced dipole (PID) phenomenon for improved open circuit voltage (Voc). This configuration, unlike previously studied ones with molecular dipoles, is based on a dipole moment which is created only under illumination and is a result of exciton dissociation. The generation of photodipoles was achieved by the creation of long-lived trapped holes inside a core of type-II ZnSe/CdS colloidal core/shell QDs, which are placed on top of the standard CdS QD sensitizer layer. Upon photoexcitation, the created photodipole negatively shifts the TiO2 energy bands, resulting in a photovoltage that is higher by ∼100 mV compared to the standard cell, without type-II QDs. The extra photovoltage gained diminishes the excessive overpotential losses caused by the energetic difference between the CdS sensitizer layer and the TiO2, without harming the charge injection processes. Moreover, we show that the extent of the additional photovoltage is controlled by the illumination intensity. This work provides new understanding regarding the operation mechanisms of photoelectrochemical cells, while presenting a new strategy for constructing a high-voltage QDSSCs. In addition, the PID effect has the potential to be implemented in other promising photovoltaic technologies.

Original languageEnglish
Pages (from-to)4456-4461
Number of pages6
JournalNano letters
Volume13
Issue number9
DOIs
Publication statusPublished - Sep 11 2013

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Keywords

  • Solar energy
  • dipole moment
  • high photovoltage cell
  • quantum dot sensitized solar cell
  • type-II QDs

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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