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Extending Carrier Diffusion via Interfacial Dielectric Shielding for Operationally Stable Perovskite/TOPCon Tandem
Wenfeng Liu1, Zhiqin Ying2, Huan Li2
1School of Energy Science and Engineering, Central South University, Changsha, China.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|January 28, 2026
Summary
A novel niobium oxide (NbOX) electron-selective contact significantly enhances the long-term operational stability of perovskite/silicon tandem solar cells. This breakthrough improves carrier diffusion, boosting both efficiency and device longevity.
Area of Science:
- Materials Science
- Renewable Energy
- Semiconductor Physics
Background:
- Perovskite/silicon tandem solar cells offer efficiencies exceeding single-junction limits but suffer from operational stability issues.
- The perovskite/C60 interface in tandems limits carrier diffusion length, exacerbating carrier accumulation and recombination.
- Textured silicon in tandems necessitates thick perovskite layers, further complicating carrier dynamics.
Purpose of the Study:
- To introduce a high-dielectric-constant niobium oxide (NbOX) electron-selective contact for perovskite/silicon tandem solar cells.
- To address carrier diffusion length limitations and improve the operational stability of these devices.
- To investigate the impact of NbOX on interfacial defect passivation and energy-level alignment.
Main Methods:
- Fabrication of single-junction perovskite solar cells and monolithic perovskite/TOPCon tandem solar cells utilizing a NbOX electron-selective contact.
- Characterization of device performance, including power conversion efficiency (PCE) and long-term operational stability under maximum power point (MPP) tracking.
- Analysis of interfacial properties, including defect suppression and chemical passivation via Pb-O bond formation.
Main Results:
- Single-junction perovskite solar cells achieved 22.4% PCE with 91% efficiency retention after 650 hours of MPP tracking.
- Monolithic perovskite/TOPCon tandem solar cells reached a certified PCE of 32.0% and maintained full initial performance after 200 hours of MPP tracking.
- The NbOX contact effectively suppressed defect-mediated carrier trapping and passivated interfacial defects, extending carrier diffusion length.
Conclusions:
- The high-dielectric NbOX electron-selective contact is crucial for enhancing both the power conversion efficiency and long-term operational stability of perovskite/silicon tandem solar cells.
- Optimizing carrier diffusion length through interfacial engineering is vital for overcoming carrier accumulation and recombination challenges.
- This work demonstrates a promising strategy for developing highly efficient and durable perovskite-based photovoltaic devices.
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