The oxidation effect of a Mo back contact on Cu(In,Ga)(Se,S)2 thin-film solar modules

Junggyu Nam, Yoonmook Kang, Dongseop Kim, Dohyun Baek, Dongho Lee, Jungyup Yang

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


We investigated the surface properties of a Mo back contact for large-area thin-film solar modules with high efficiency and good adhesion between Mo and the absorber layer. It was determined that the appropriate surface properties of Mo would improve the efficiency from 10% to above 15.0±0.21% and narrow the efficiency distribution in large-area modules. The Mo back contact was annealed at various temperatures between room temperature and 230 °C in air to control the amount of sodium diffusing from the soda-lime glass substrate during selenization and sulfurization, and to improve the uniformity of the unit cell. Before the heat treatment, the amount of sodium in the patterned area of the unit cell was more than 10 times of that in the central area of the cell. The patterned region with higher Na content had smaller grains than those in the central area with less Na, resulting in many peel-offs and shunting paths. The difference in sodium content was reduced after heat treatment. The optimized surface oxide of the Mo back contact had a thickness of around 3-5 nm and consisted of the MoO3 phase. The grain boundary of Mo columnar structure near the surface consisted of the oxide layer.

Original languageEnglish
Pages (from-to)445-450
Number of pages6
JournalSolar Energy Materials and Solar Cells
Publication statusPublished - 2016 Jan 1


  • Abbreviations BZO boron-doped zinc oxide
  • CBD chemical bath deposition
  • CIGSS copper-indium-gallium-sulfur selenide, Cu(In,Ga)(Se,S)
  • FF fill factor
  • IR imaging infrared imaging
  • LPCVD low-pressure chemical vapor deposition
  • SEM scanning electron microscopy
  • SIMS secondary ion mass spectroscopy
  • TCO transparent conductive oxide
  • TEM transmission electron microscopy
  • XPS X-ray photoelectron spectroscopy

ASJC Scopus subject areas

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


Dive into the research topics of 'The oxidation effect of a Mo back contact on Cu(In,Ga)(Se,S)2 thin-film solar modules'. Together they form a unique fingerprint.

Cite this