Stoichiometric dependence of TiOx as a cathode modifier on band alignment of polymer solar cells

Yun Chieh Yeh, Shao Sian Li, Chao Chuan Wu, Teng Wei Shao, Pai Chia Kuo, Chun Wei Chen

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10 Citations (Scopus)

Abstract

In this study, we systematically investigated the stoichiometric dependence of titanium oxide (TiOx, x=1.56-1.93) as a cathode modifier on the device performance of polymer solar cells. Electronic structures of the synthesized TiOx modifier layers were controlled by tuning the compositions of various O/Ti ratios. The effective cathode work-functions and the corresponding device performances of polymer solar cells are systematically changed as a result of inserting the TiOx modification layers. Interfacial modification of the Al cathode with a low O/Ti ratio of TiO x layer yields the best performing photovoltaic device as a result of a largest built-in potential. The correlation of power conversion efficiencies and carrier dynamics of these devices by inserting various TiOx modification layer is further examined by using the Mott-Schottky analysis and the impedance spectroscopy technique. The consistent result shows an enhanced carrier collection efficiency and a reduced charge recombination rate of the device via adequate band alignment between the photoactive layer and the cathode using the TiOx modification layer with an optimized O/Ti ratio.

Original languageEnglish
Pages (from-to)233-238
Number of pages6
JournalSolar Energy Materials and Solar Cells
Volume125
DOIs
Publication statusPublished - Jan 1 2014
Externally publishedYes

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Keywords

  • Built-in potential
  • Cathode work-function
  • Charge recombination
  • Polymer solar cell
  • Solution processable

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films

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