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Fabrication of Robust Nanoscale Contact between a Silver Nanowire Electrode and CdS Buffer Layer in CuIn,GaSe2 Thin-film Solar Cells
Published on: July 19, 2019
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Interdiffusion and Doping Gradients at the Buffer/Absorber Interface in Thin-Film Solar Cells.
Florian Werner1, Finn Babbe1, Jan Burkhart1
1Laboratory for Photovoltaics, Physics and Materials Science Research Unit , University of Luxembourg , Rue du Brill 41 , L-4422 Belvaux , Luxembourg.
ACS Applied Materials & Interfaces
|August 1, 2018
Summary
Accurate doping profiles in thin-film solar cells are crucial. Intermixing at the absorber/buffer interface significantly alters apparent dopant concentration, impacting device performance analysis.
Area of Science:
- Materials Science
- Solid State Physics
- Photovoltaics
Background:
- Accurate net dopant concentration determination is vital for optimizing solar cell performance.
- Multilayered thin-film solar cell structures complicate doping analysis.
- Capacitance-voltage (C-V) measurements often yield inconsistent doping profiles compared to Hall measurements.
Purpose of the Study:
- To investigate the discrepancies between C-V and Hall measurements in photovoltaic absorbers.
- To identify the factors causing inaccurate doping profiles in thin-film solar cells.
- To provide a more accurate method for interpreting doping profiles in multilayered solar cells.
Main Methods:
- Capacitance-voltage (C-V) measurements on Cu(In,Ga)Se2 thin-film solar cells with different buffer layers (CdS, Zn(O,S), MgF2).
- Hall effect measurements on bare absorbers for comparison.
- Photoluminescence (PL) spectroscopy to analyze near-surface properties before and after buffer layer deposition.
Main Results:
- C-V measurements in devices with CdS or Zn(O,S) buffer layers indicated a linearly graded junction, inconsistent with Hall measurements.
- Deep defects did not fully explain the observed doping profile discrepancies.
- C-V measurements agreed well with Hall measurements for absorbers coated with MgF2.
- PL measurements showed a reduced near-surface dopant concentration after CdS deposition.
Conclusions:
- Elemental intermixing at the absorber/buffer interface significantly alters the apparent dopant concentration in thin-film solar cells.
- This interdiffusion effect is a critical factor in interpreting C-V doping profiles.
- The true bulk dopant concentration in thin-film devices may differ substantially from C-V derived values.
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