Advancements in material compositions have played a critical role in significantly improving the efficiency of perovskite-silicon tandem solar cells, pushing their performance well beyond the limits of traditional single-junction silicon cells. Key material innovations include:
Tunable Bandgap Perovskites
- Perovskite materials can be engineered with adjustable bandgaps typically between 1.15 eV and 3.1 eV. For tandem cells, an ideal perovskite top cell bandgap lies between 1.67 and 1.75 eV to optimally complement the 1.12 eV silicon bottom cell, maximizing the absorption of different parts of the solar spectrum.
- The ability to precisely tune these bandgaps in hybrid 2D/3D perovskites enhances light absorption and reduces energy loss, enabling higher photocurrent generation and overall efficiency.
Defect Passivation and Interface Engineering
- Introduction of high-efficiency defect passivation materials within the perovskite layer significantly reduces recombination losses caused by defects and trap states, improving charge carrier lifetime and open-circuit voltage. This has been crucial in raising tandem cell efficiencies into the mid-30% range.
- Advanced interface passivation structures have been developed to optimize the contact between the perovskite and silicon layers as well as electron/hole transport layers. This reduces interface recombination and improves charge extraction.
Optimized Electron Transport Layers and Transparent Contacts
- Replacement or improvement of traditional electron transport materials such as buckminsterfullerene (C60) with more transparent and conductive alternatives has allowed better light transmission and lower series resistance, directly boosting cell efficiency.
- Similarly, finding alternatives to commonly used transparent conductive oxides like indium tin oxide (ITO) further enhances transparency and reduces parasitic absorption losses in the tandem structure.
Enhanced Stability via Material Additives and Encapsulation
- Stability improvements have come from incorporating organic stabilizers and additives, such as dimethylammonium formate, which help prevent rapid oxidation and degradation of the perovskite layer under operational conditions.
- Advanced encapsulation techniques protect the sensitive perovskite materials from moisture, oxygen, and thermal stress, which historically limited their commercial viability.
Light Management Through Textured Surfaces and Nano-Textures
- Although not strictly a compositional change, deposition of perovskite on substrates with nano-textures or planarized layers improves light absorption and uniformity of the perovskite film, which is critical given the thin (~500 nm) perovskite layers required.
- Conformal deposition techniques and managing surface roughness ensure high-quality films with fewer pinholes and defects, indirectly improving electronic material quality.
Summary Table of Key Material Composition Advancements
| Advancement | Impact on Efficiency |
|---|---|
| Tunable perovskite bandgap (1.67-1.75 eV) | Maximizes spectral utilization with silicon bottom cell |
| Defect passivation materials | Reduces trap-assisted recombination, improves Voc and FF |
| Interface passivation structures | Minimizes interface recombination, enhances charge transfer |
| Improved electron transport layers | Increases transparency and conductivity, reduces losses |
| Transparent conductive layer improvements | Reduces parasitic absorption, boosts photocurrent |
| Organic additives for stability | Enhances environmental durability of perovskite layer |
| Advanced encapsulation | Protects from moisture/oxygen/thermal degradation |
| Nano-texturing & planarization | Improves light management and film uniformity |
These material composition innovations have enabled silicon-perovskite tandem cells to achieve record efficiencies of 34.6% as demonstrated by LONGi in 2024, approaching theoretical limits for practical tandem architectures. Further material optimization in transport layers, defect passivation, and stability is expected to push efficiencies closer to the predicted practical maximum of nearly 40% and improve durability for commercial deployment.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-advancements-in-material-compositions-have-been-most-effective-in-improving-the-efficiency-of-perovskite-silicon-tandem-cells/
