Investigation of Surface Sulfurization in CuIn1-xGaxS2-ySey Thin Films by using Kelvin Probe Force Microscopy

Haeri Kim, Se Jin Park, Byungwoo Kim, Yun Jeong Hwang, Byoung Koun Min

Research output: Contribution to journalArticle

Abstract

CuIn1-xGaxS2-ySey (CIGSSe) thin films have attracted a great deal of attention as promising absorbing materials for solar cell applications, owing to their favorable optical properties (e.g. a direct band gap and high absorption coefficients) and stable structure. Many studies have sought to improve the efficiency of solar cells using these films, and it has been found that surface modification through post-heat treatment can lead to surface passivation of surface defects and a subsequent increase in efficiency. The surface properties of solution-processed CIGSSe films are considered to be particularly important in this respect, owing to the fact that they are more prone to defects. In this work, CIGSSe thin films with differing S/Se ratios at their surface were synthesized by using a precursor solution and post-sulfurization heat treatment. These CIGSSe thin films were investigated with current-voltage and Kelvin probe force microscope (KPFM) analyses. Surface photovoltage (SPV), which is the difference in the work function in the dark and under illumination, was measured by using KPFM, which can examine the screening and the modification of surface charge through carrier trapping. As the concentration of S increases on the CIGSSe film surface, higher work functions and more positive SPV values were observed. Based on these measurements, we inferred the band-bending behavior of CIGSSe absorber films and proposed reasons for the improvement in solar cell performance.

Original languageEnglish
JournalChemPhysChem
DOIs
Publication statusAccepted/In press - 2018 Jan 1

Fingerprint

Atomic Force Microscopy
Microscopic examination
microscopy
Thin films
probes
thin films
Hot Temperature
Solar cells
Surface Properties
Lighting
solar cells
Microscopes
photovoltages
Heat treatment
heat treatment
Surface defects
microscopes
Surface charge
Passivation
Surface properties

Keywords

  • Defects
  • Kelvin probe force microscopy
  • Sulfurization
  • Surface photovoltage
  • Thin films

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

Cite this

Investigation of Surface Sulfurization in CuIn1-xGaxS2-ySey Thin Films by using Kelvin Probe Force Microscopy. / Kim, Haeri; Park, Se Jin; Kim, Byungwoo; Hwang, Yun Jeong; Min, Byoung Koun.

In: ChemPhysChem, 01.01.2018.

Research output: Contribution to journalArticle

Kim, Haeri ; Park, Se Jin ; Kim, Byungwoo ; Hwang, Yun Jeong ; Min, Byoung Koun. / Investigation of Surface Sulfurization in CuIn1-xGaxS2-ySey Thin Films by using Kelvin Probe Force Microscopy. In: ChemPhysChem. 2018.
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