An Interhalogen-Based Binary Redox Couple for the Efficiency Enhancement of Type-II Dye-Sensitized Solar Cells

Md Mahbubur Rahman, Francis Kwaku Asiam, Narayan Chandra Deb Nath, Jae Joon Lee

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

In this work, the photovoltaic (PV) performance of dye-sensitized solar cells (DSSCs), sensitized with salicylic acid (SA) and indole-3-acetic (IAA) and mediated by iodide (I)/tri-iodide (I3), binary-redox system (I, Br)/(I3, I2Br), and bromide (Br)/tri-bromide (Br3), were investigated. The (I, Br)/(I3, I2Br) redox electrolyte induced the highest recombination resistance at the TiO2/dye/electrolyte interface for both SA and IAA-sensitized DSSCs. Concurrently, additive-free binary electrolyte-based cells showed enhanced dye regeneration capability and decreased rate of back reaction compared to the cells prepared with additive-free I/I3 and Br/Br3 electrolytes. Energy band alignment of SA and IAA and the optical analyses revealed the direct one-step electron injection into the conduction band of TiO2 upon photoexcitation. Further, additive-containing electrolytes showed decreased PV performance compared to the additive-free electrolytes in both molecules sensitized DSSCs, conceivably due to the increased rate of back reaction with decreased charge collection efficiency. Thus, a maximum power conversion efficiency (PCE) of 0.57 % was attained for SA-sensitized DSSCs based on additive-free binary redox mediator, while the PCE values for additive-free I/I3 and Br/Br3 electrolytes-based identical cells were 0.19 and 0.54 %, respectively. This research suggests that the binary redox couple is a potential candidate for the PCE improvement of type-II DSSCs.

Original languageEnglish
Article numbere202300704
JournalChemistrySelect
Volume8
Issue number35
DOIs
StatePublished - 20 Sep 2023

Keywords

  • binary electrolyte
  • dye-sensitized solar cell
  • dye-to-TiO charge-transfer
  • electron injection. type-II sensitizer

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