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Solution-Processed "Silver-Bismuth-Iodine" Ternary Thin Films for Lead-Free Photovoltaic Absorbers
Published on: September 27, 2018
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High Photon-to-Current Conversion in Solar Cells Based on Light-Absorbing Silver Bismuth Iodide
Huimin Zhu1, Mingao Pan1, Malin B Johansson1
1Department of Chemistry- Ångström, Div. Physical Chemistry, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden.
Chemsuschem
|May 9, 2017
Summary
Researchers developed a new lead-free silver bismuth iodide solar cell achieving over 2% efficiency. This novel material demonstrates promising photovoltaic performance, surpassing previous bismuth-halide solar cells.
Area of Science:
- Materials Science
- Renewable Energy
- Solid-State Physics
Background:
- The development of efficient and stable lead-free solar cells is crucial for sustainable energy.
- Bismuth-halide materials are emerging as promising alternatives to lead-based perovskites.
- Previous bismuth-halide solar cells have shown limited power conversion efficiencies.
Purpose of the Study:
- To investigate a novel lead-free silver bismuth iodide (AgI/BiI3) compound for solar cell applications.
- To evaluate the photovoltaic performance of devices incorporating this new material.
- To compare the performance with existing bismuth-halide solar cell technologies.
Main Methods:
- Solution deposition of silver bismuth iodide onto TiO2 and poly(3-hexylthiophene-2,5-diyl) (P3HT) layers.
- Fabrication and characterization of solar cell devices.
- Analysis of X-ray diffraction for crystal structure determination.
- Measurement of photocurrent generation and external quantum efficiency (EQE).
- Determination of optical band gap energies (indirect and direct) from absorption spectra.
Main Results:
- A novel lead-free silver bismuth iodide with a hexagonal crystal structure (space group R3‾m) was synthesized.
- Solar cells fabricated with this material achieved a power conversion efficiency exceeding 2%.
- Photocurrent generation was observed in the 350-700 nm range, with a maximum EQE of approximately 45%.
- The new material demonstrated significantly higher performance compared to previously reported AgBi2I7-based solar cells.
- An indirect band gap of 1.62 eV and a direct band gap of 1.85 eV were determined.
Conclusions:
- The newly investigated silver bismuth iodide composition and crystal structure offer enhanced photovoltaic performance.
- This work highlights the potential of exploring new metal-halide structures for efficient lead-free solar cells.
- Further research into lead-free metal-halide solar cells is warranted, focusing on novel material discovery and device optimization.
