A Hybrid Electrode to Supercharge Space-Grade Solar Cells
An international team of researchers has developed a new transparent electrode that could significantly improve the efficiency of solar cells used in space.
The Innovation
Scientists from the University of Salerno (Italy), Warsaw University (Poland), and the Center for Physical Sciences and Technology (Lithuania) created a hybrid electrode by combining graphene with indium tin oxide (ITO).
- The goal was to enhance charge transport in high-performance multijunction solar cells (GaInP/GaAs/Ge), which are standard in aerospace applications.
- The monolayer graphene was synthesized via cold-wall chemical vapor deposition and transferred onto ITO-coated glass using thermal release tape.
Critical Findings
The hybrid structure dramatically outperformed bare ITO at the nanoscale.
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Raman Spectroscopy confirmed the graphene was high-quality, showing characteristic D, G, and 2D peaks with minimal defects and strong interfacial coupling with the ITO.
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Nanoscale Conductivity (TUNA-AFM): Under a 1-2V DC bias, the performance leap was clear:
- Bare ITO: Tunneling currents ranged from -950 fA to 940 fA, with conduction concentrated at grain boundaries.
- Graphene-coated ITO: Tunneling currents jumped to a range of -1.6 pA to 1.5 pA, featuring a smoother morphology and continuous conductive pathways.
This represents an approximately 60% increase in nanoscale tunneling current.
The researchers attribute this improvement to graphene's exceptional in-plane conductivity and the strong interfacial coupling between the two materials.
Implications for Aerospace
The new hybrid electrode directly addresses the major limitations of conventional ITO: the inherent trade-off between conductivity and transparency, as well as its mechanical brittleness.
- These structures could pave the way for lightweight, durable, and high-efficiency solar cells specifically designed for harsh aerospace environments.
Next Steps
While the nanoscale results are highly promising, the team notes that further device-level studies are required to assess the real-world performance gains in operational solar cells under space conditions.