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Nonlinear Band Gap Dependence of Mixed Pb-Sn 2D Ruddlesden-Popper PEA2Pb1-SnI4 Perovskites
Cameron C L Underwood1, J David Carey1, S Ravi P Silva1
1Advanced Technology Institute, Department of Electrical & Electronic Engineering, University of Surrey, Guildford GU2 7XH, U.K.
The Journal of Physical Chemistry Letters
|February 3, 2021
Summary
This study reveals a nonlinear band gap in 2D Ruddlesden-Popper perovskites (RPPs) with mixed tin content. This insight is crucial for designing advanced 2D perovskite materials for optoelectronic devices.
Area of Science:
- Materials Science
- Solid-State Physics
- Optoelectronics
Background:
- Two-dimensional (2D) Ruddlesden-Popper perovskites (RPPs) are versatile materials used in photovoltaics and light-emitting diodes.
- Tuning the properties of RPPs is essential for optimizing device performance.
Purpose of the Study:
- To investigate the nonlinear band gap behavior in mixed-phase 2D RPPs (PEA2Pb1-xSnxI4) as a function of tin (Sn) content.
- To understand the underlying electronic structure responsible for this nonlinearity.
Main Methods:
- Density functional theory (DFT) calculations were performed with and without spin-orbit coupling.
- Analysis of partial density of states (PDOS) was used to study the electronic structure.
- Investigated compositions with varying Sn content (x = 0, 0.25, 0.5, 0.75, 1).
Main Results:
- A nonlinear band gap behavior was observed with increasing Sn content in the mixed-phase 2D RPPs.
- The nonlinearity is attributed to the energy mismatch between lead (Pb) 6s and tin (Sn) 5s states at the valence band maximum.
- A bowing parameter in the range of 0.35–0.38 eV was determined.
Conclusions:
- The findings provide critical insights for designing novel metal-alloyed 2D perovskite materials.
- The tunable energy band discontinuity suggests potential for intraband transitions relevant to device engineering.
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