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Published on: September 27, 2018
Solution-processed Ge(ii)-based chalcogenide thin films with tunable bandgaps for photovoltaics
Liyan Hu1,2, Mingjie Feng1,3, Xia Wang4
1Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 China djxue@iccas.ac.cn.
Researchers developed a new solution-based method for creating germanium (Ge)-based chalcogenide thin films, overcoming previous oxidation challenges. This breakthrough enables low-cost manufacturing of high-performance optoelectronic devices like solar cells.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Optoelectronics
Background:
- Solution processing offers high performance and low-cost manufacturing for chalcogenide thin films.
- Germanium (Ge)-based chalcogenide films are promising for optoelectronics but challenging to produce via solution methods due to Ge(ii) oxidation.
- Existing methods struggle with the instability of Ge(ii) precursors, which readily oxidize to Ge(iv).
Purpose of the Study:
- To report the first solution-processed deposition of Ge(ii)-based chalcogenide thin films (GeSe and GeS).
- To address the challenge of Ge(ii) oxidation in precursor solutions.
- To enable tunable bandgaps for optimized optoelectronic device performance.
Main Methods:
- Utilized hypophosphorous acid as a reducing agent and strong acid.
- Generated Ge(ii) from stable and low-cost GeO2 powders.
- Controlled Ge(ii) stability by suppressing oxidation to Ge(iv) in precursor solutions.
- Deposited GeSe1-xSx alloy films with tunable bandgaps.
Main Results:
- Successfully deposited GeSe and GeS thin films using a solution-based approach.
- Demonstrated the effectiveness of hypophosphorous acid in stabilizing Ge(ii) precursors.
- Achieved continuously tunable bandgaps in GeSe1-xSx alloy films from 1.14 eV (GeSe) to 1.71 eV (GeS).
Conclusions:
- Solution-processed Ge(ii)-based chalcogenide thin films are now feasible.
- The developed method allows for cost-effective fabrication of optoelectronic devices.
- Tunable bandgaps enable optimization for single-junction and multi-junction photovoltaic applications.
