The most effective methods to reduce hysteresis in perovskite solar cells (PSCs) primarily involve careful engineering of materials and interfaces to mitigate ion migration and nonradiative recombination, which are key causes of hysteresis.
Key Methods to Reduce Hysteresis in Perovskite Solar Cells
1. Interfacial Engineering
- Modifying the interfaces between the perovskite layer and charge transport layers (electron transporting layer (ETL) and hole transporting layer (HTL)) effectively reduces hysteresis by limiting ion migration and recombination at these boundaries.
- For example, inserting a NaBr interlayer on the ETL has been demonstrated to improve charge carrier dynamics, significantly reducing hysteresis and boosting efficiency. This approach reduced the hysteresis index dramatically while achieving over 21% efficiency.
- Improving the quality of contacts and reducing surface recombination helps simultaneously lower hysteresis and enhance power conversion efficiency.
2. Bulk Defect Engineering
- Defects within the perovskite bulk act as recombination centers and facilitate ion migration, both of which intensify hysteresis.
- Engineering to reduce these bulk defects is seen as the most promising route to completely remove hysteresis. Approaches like doping with potassium iodide (KI) have been identified as universally effective across various perovskite compositions for hysteresis-free PSCs.
3. Optimizing Electron Transport Layers (ETLs)
- Low-temperature thermal annealing of SnO2 ETLs can substantially improve their electrical conductivity, helping to balance charge transport and thereby reduce hysteresis.
- Enhancing ETL conductivity diminishes charge transport imbalance, which is a significant factor in hysteresis in planar perovskite solar cells. Thermal annealing of SnO2 ETLs led to stabilized output powers and reduced hysteresis behavior.
4. Enhancing Charge Carrier Diffusion Length and Reducing Surface Recombination
- Numerical simulation and experiments highlight that hysteresis is minimized when charge carrier diffusion lengths are long and surface recombination at contacts is low.
- Achieving these transport properties ensures less hysteresis and greater solar cell efficiency, indicating that improving bulk material quality and interface passivation are critical.
Summary Table of Methods
| Method | Mechanism | Examples/Notes |
|---|---|---|
| Interfacial Engineering | Reduces ion migration and recombination | NaBr interlayer at ETL reduces hysteresis index from 0.135 to 0.025 |
| Bulk Defect Engineering | Minimizes defects that facilitate ion migration and recombination | KI doping universally reduces hysteresis across compositions |
| Thermal Annealing of ETLs | Improves ETL conductivity, balances charge transport | Low-temp annealing of SnO2 ETLs reduces hysteresis, boosts efficiency |
| Enhancing Charge Transport | Increases carrier diffusion length, lowers surface recombination | Longer diffusion length and better interface passivation required |
Overall, combining these methods—especially bulk defect reduction via doping, interfacial modification (e.g., with NaBr), and ETL optimization through thermal annealing—represents the state-of-the-art strategy for minimizing hysteresis while maximizing the performance and stability of perovskite solar cells.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-most-effective-methods-to-reduce-hysteresis-in-perovskite-solar-cells/
