Band Gap Vs Pressure: Proskite Compounds

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SUMMARY

The discussion focuses on the relationship between band gap reduction and increased pressure in perovskite compounds, specifically CsPbBr3. The generic Hubbard model is referenced, highlighting the U/W ratio, where U represents on-site Coulomb repulsion and W denotes bandwidth. As pressure increases, ions in the lattice are compressed, leading to an increase in U. If the bandwidth remains constant, this results in a higher U/W ratio, which typically correlates with an increase in bandgap size. However, variations in bandwidth under pressure can lead to differing behaviors in bandgap changes across various compounds.

PREREQUISITES
  • Understanding of the Hubbard model in solid-state physics
  • Knowledge of band structure and bandgap concepts
  • Familiarity with perovskite materials, particularly CsPbBr3
  • Basic principles of pressure effects on material properties
NEXT STEPS
  • Research the Hubbard model and its application in band structure analysis
  • Explore the effects of pressure on the electronic properties of perovskite compounds
  • Investigate the specific properties of CsPbBr3 under varying pressure conditions
  • Review published studies on bandgap behavior in response to external pressures
USEFUL FOR

Researchers, physicists, and materials scientists interested in the electronic properties of perovskite compounds and their behavior under pressure conditions.

new_986
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why band gap reduces when pressure increased for provskite compounds ?

Nawzad
 
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new_986 said:
why band gap reduces when pressure increased for provskite compounds ?

Nawzad

It should always be a practice to provide exact citation to a published paper when you're asking something of this nature.

Without knowing exactly the details, and at what level you're asking this, the generic Hubbard model for the band structure contains a U/W ratio, where U is the on-site Coulomb repulsion, and W is the bandwidth. When you increase pressure, the ions in the lattice are pushed closer, and thus, it increases U. If the bandwidth doesn't change, then the ratio U/W also increases. However, this usually translates into an increase in the size of the bandgap, i.e. the bottom of the conduction band moves away from the top of the valence band.

The bandwidth can easily change with pressure, so the ratio of U/W may behave differently for different compounds. But without proper citation, I do not have an explanation for your question.

Zz.
 

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