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Band-Gap Tuning in All-Inorganic CsPbSn1-Br3 Perovskites
Heidi A Schwartz1, Hannah Laurenzen1, Asma Marzouk2
1Department of Chemistry, University of Cologne, Greinstrasse 4-6, 50939 Cologne, Germany.
ACS Applied Materials & Interfaces
|January 13, 2021
Summary
This study explores CsPbSn1-xBr3 perovskite thin films, revealing tunable band gaps crucial for tandem solar cells and LEDs. The electronic structure shows valence band shifts with Pb/Sn ratio, while the conduction band remains stable.
Area of Science:
- Materials Science
- Solid State Physics
- Optoelectronics
Background:
- All-inorganic perovskites offer tunable optoelectronic properties.
- Controlling the band gap is essential for advanced device applications.
- Understanding the electronic structure variations is key to material optimization.
Purpose of the Study:
- To investigate the relationship between Pb/Sn ratio and the band gap in CsPbSn1-xBr3 perovskite thin films.
- To analyze the impact of compositional changes on the electronic band structure.
- To assess the potential of these materials for optoelectronic devices.
Main Methods:
- Synthesis of CsPbSn1-xBr3 thin films with varying Pb/Sn ratios.
- Optical spectroscopy to determine band gap energies.
- Photoelectron spectroscopy to probe electronic band structure.
Main Results:
- The band gap of CsPbSn1-xBr3 is tunable from 1.86 eV to 2.37 eV with varying Pb/Sn ratio (x).
- A nonlinear band gap tuning with a bowing parameter of 0.9 eV was observed.
- A slight band gap narrowing occurred at low Pb content (x ~ 0.3).
- Valence band energy shifts were observed with changes in Pb/Sn ratio, while the conduction band remained largely unaffected.
Conclusions:
- CsPbSn1-xBr3 perovskites exhibit wide band gap tunability, making them suitable for tandem solar cells and tunable LEDs.
- The nonlinear band gap behavior and valence band modulation offer pathways for precise material engineering.
- The stability of the conduction band suggests robust electronic properties for device applications.
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