Development Status and Trends of New Solar Cell Materials
I. Perovskite Solar Cells
Material Characteristics and Advantages
Perovskite materials have high absorption coefficient, long carrier diffusion length and low non-radiative recombination rate, and the laboratory efficiency has exceeded 30%17. Its preparation process is simple (solution method or vapor deposition), the cost is lower than that of crystalline silicon cells, and the band gap (1.2-2.3eV) can be adjusted by components, which is suitable for multi-junction stacking design.
Application breakthrough: The Beijing Institute of Technology team solved the problem of uneven wide-bandgap perovskite film by adding long-chain alkylamines and prepared a high-efficiency stacking cell prototype.
Challenges and Improvement Directions
Stability: It is easily affected by humidity, ultraviolet light and temperature, and the life span needs to be improved by interface passivation and packaging technology (such as glass/polymer packaging).
Environmental protection: Lead-based perovskites are toxic, and research has turned to lead-free perovskites (such as cesium-tin-based)16. 2. Organic solar cells
Material properties and applications
Organic materials (such as polymers and small molecules) are lightweight, flexible, and solution-processable, making them suitable for the preparation of transparent/flexible devices. The graphene-electrode organic solar cell developed by MIT has both high conductivity and optical transparency and can be attached to windows and car surfaces.
Efficiency progress: The laboratory efficiency reaches 19%, but the efficiency decays significantly when it is prepared on a large scale.
Technical optimization
Interface engineering: Optimize the matching of donor and acceptor materials through molecular design to improve carrier mobility.
Device structure: Inverted organic solar cells (ITIC acceptors) can reduce energy loss6.
3. Dye-sensitized solar cells (DSSC)
Core advantages
Using dye-sensitized layers (such as ruthenium complexes), titanium dioxide semiconductors and iodine electrolytes, it can work in weak light, and is low-cost and environmentally friendly.
Innovation direction: Quantum dot dyes (such as lead sulfide) can broaden the spectral absorption range and increase efficiency to 12%.
Challenges
The electrolyte is prone to leakage, and solid electrolyte alternatives need to be developed6.
IV. Other cutting-edge materials
Nanocrystalline solar cells
Nanocrystalline materials (such as quantum dots) have high quantum efficiency, with theoretical efficiency exceeding 30%, but the problem of grain interface defects needs to be solved.
Triple-junction cell: GaInP/GaAs/Ge structure has an efficiency of 33%, suitable for aerospace.
New quantum materials
The "intermediate band state" material developed by Lehigh University achieves 190% external quantum efficiency through copper intercalation, breaking the Shockley-Queisser theoretical limit.
V. Future trends and challenges
Technical direction
Lightweight and flexible: Develop wearable and building-integrated photovoltaic materials (such as transparent photovoltaic glass and photovoltaic tiles).
Environmental protection and low cost: Promote lead-free perovskites and bio-based organic materials.
Industrial bottleneck
Large-scale production: need to solve the problem of efficiency attenuation during large-scale preparation (such as perovskite printing process).
Stability verification: need to pass IEC standard test (such as heat/light aging)