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Optimizing the role of impact ionization in conventional insulators
1Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32306-4350, USA. manousakis@gmail.com.
Scientific Reports
|January 2, 2020
Summary
Impact ionization (IA) in conventional insulators generates multiple carriers with lighter mass for efficient separation. This mechanism may explain the high photovoltaic efficiency in halide perovskites.
Area of Science:
- Solid State Physics
- Materials Science
- Photovoltaics
Background:
- Existing impact ionization (IA) mechanisms are primarily for strongly correlated insulators.
- Conventional insulators with localized bands near the Fermi level are less explored for IA-based carrier generation.
Purpose of the Study:
- Generalize the IA mechanism for multiple carrier generation to conventional insulators.
- Investigate the role of localized band hybridization in enhancing carrier generation and separation.
- Propose IA as a potential contributor to the high photovoltaic efficiency of halide perovskites.
Main Methods:
- Theoretical generalization of the impact ionization mechanism.
- Analysis of localized orbital hybridization with dispersive bands.
- Modeling carrier dynamics and mass acquisition during IA decay.
Main Results:
- Demonstrated IA-driven multiple carrier generation in conventional insulators with localized bands.
- Showed that hybridized carriers acquire lighter effective mass, facilitating efficient separation.
- Identified potential applications in halide perovskites for enhanced photovoltaic performance.
Conclusions:
- The generalized IA mechanism offers a new pathway for efficient carrier generation in semiconductors.
- Lighter carrier mass resulting from IA is crucial for improved charge separation and photovoltaic efficiency.
- Material selection criteria are discussed for optimizing IA effects across the solar spectrum.
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