Current Applied Physics

Korean Physical Society (한국물리학회)
권호 표지
DOI QR코드

DOI QR Code

Reduction of point defects and Cu surface composition in Cu(In,Ga)Se2 film by Se annealing with a NaF overlayer at intermediate temperatures

  • Kim, Suncheul (Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Ko, Young Min (Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Kim, Seung Tae (Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Choi, Yong Woo (Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Park, Joong Keun (Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Ahn, Byung Tae (Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology)
  • Received : 2016.12.12
  • Accepted : 2017.03.07
  • Published : 2017.05.31
⟨ Previous Next ⟩

Abstract

Donor-type point defects such as a Se vacancy or cation antisite in $Cu(In,Ga)Se_2$ (CIGS) films were controlled by Se annealing of CIGS film. The photoluminescence intensities originating from such defects were reduced by Se annealing at $300^{\circ}C$. The short-circuit current of the CIGS solar cell with the Se annealing increased but the fill factor and open-circuit voltage were degraded due to the out-diffusion of Cu from the bulk to the CIGS surface. With a NaF overlayer on the CIGS film the Cu concentration at the CIGS surface was decreased by Se annealing at $300^{\circ}C$. The literature has demonstrated that the Cu concentration is reduced by applying both NaF and KF together on the CIGS film. However, we found that the application of a NaF overlayer also greatly reduced the Cu concentration at the CIGS surface. In addition, the Na concentration increased greatly at the CIGS surface, forming a desirable surface layer with a lower valence band maximum. As a result, in addition to the increase of short-circuit current, the fill factor and open-circuit voltage increased significantly. The origin of the improvement in cell performance is described by analyzing the point defects from low-temperature photoluminescence, the valence band maximum from x-ray photoelectron spectroscopy, the reverse saturation current from diode curves, and the carrier lifetimes from time-resolved photoluminescence.

Keywords

Acknowledgement

Supported by : KAIST

Cited by

  1. Review of grain interior, grain boundary, and interface effects of K in CIGS solar cells: Mechanisms for performance enhancement vol.172, pp.None, 2017, https://doi.org/10.1016/j.solmat.2017.07.006
  2. Surface passivation and point defect control in Cu(In,Ga)Se2 films with a Na2S post deposition treatment for higher than 19% CIGS cell performance vol.3, pp.3, 2017, https://doi.org/10.1039/c8se00570b
  3. Impact of heat‐light soaking and heat‐bias soaking on NaF‐treated CIGS thin film solar cells vol.27, pp.7, 2017, https://doi.org/10.1002/pip.3135
  4. Passivation of Deep-Level Defects by Cesium Fluoride Post-Deposition Treatment for Improved Device Performance of Cu(In,Ga)Se2 Solar Cells vol.11, pp.39, 2017, https://doi.org/10.1021/acsami.9b08316
  5. Performance Improvement by Controlling Se/metal Ratio and Na2S Post Deposition Treatment in Cu(In,Ga)3Se5 Thin-Film Solar cell vol.7, pp.4, 2017, https://doi.org/10.21218/cpr.2019.7.4.103
  6. Review on the effects due to alkali metals on copper-indium-gallium-selenide solar cells vol.20, pp.None, 2017, https://doi.org/10.1016/j.mtener.2020.100617
  7. Decay of excess carriers in a two-defect model semiconductor: A time-resolved photoluminescence study vol.130, pp.23, 2021, https://doi.org/10.1063/5.0065600