Quantifying interface states and bulk defects in high-efficiency solution-processed small-molecule solar cells by impedance and capacitance characteristics

Viktor V. Brus, Aung Ko Ko Kyaw, Pavlo D. Maryanchuk, Jie Zhang

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

The AC properties of high-efficiency (η = 8.01%) small-molecule bulk heterojunction solar cells (p-DTS(FBTTh2)2/PC70BM) at different DC biases and frequencies of small amplitude AC signal in the dark at room temperature were investigated. We showed the presence of interface states at the heterojunction interface and determined their parameters from the analysis of the measured impedance spectroscopy. We also quantitatively determined the density of defect states in the bulk (N = 1.05 × 1016 cm-3) from the high frequency C-V characteristic

The AC properties of high-efficiency (η = 8.01% under standard 100 mW/cm2 AM1.5 illumination) small-molecule bulk heterojunction (SM BHJ) solar cells (p-DTS(FBTTh2)2/PC70BM) at different DC biases and frequencies of small amplitude (±10 mV) AC signal in the dark at room temperature were investigated in details. We showed the presence of interface states at the heterojunction interface and determined their parameters from the analysis of spectral distributions of real and imaginary components of the measured impedance. The dielectric constant of BHJ εBHJ = 2.9 was determined from the geometrical capacitance of totally depleted BHJ layer. We explained quantitatively the effect of interface states and series resistance on the measured C-V characteristics of the SM BHJ solar cells at both low and high frequencies. The quantitative value of the density of defect states in the bulk N = 1.05 × 1016 cm-3 was determined from the high frequency C-V characteristic corrected by the effect of the series resistance.

Original languageEnglish
Pages (from-to)1526-1535
Number of pages10
JournalProgress in Photovoltaics: Research and Applications
Volume23
Issue number11
DOIs
Publication statusPublished - Nov 2015
Externally publishedYes

Keywords

  • bulk defects
  • dielectric constant
  • interface states
  • small-molecule sole cells

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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