Principle of triple junction nanowires for solar cells

WP3: Up scaling and integration of III-V nanowire solar cells and III-V power transmission nanowire devices on Silicon

Our research is focused on upscaling solar cells to sizes up to 100 mm, with a strong emphasis on optimizing manufacturing processes for minimal defects and high yield. This scaling involves developing advanced surface passivation schemes specifically tailored for large-area devices, which is crucial for maintaining efficiency as cell size increases.

To further enhance performance, we are implementing highly efficient front contact designs for these larger cells. This includes using buried front contacts, minimizing ITO coverage to reduce optical losses, and employing SEM (Scanning Electron Microscopy) for detailed morphology analysis to continually improve contact quality.

WP2: Explore Wireless microwave transmission-detection with nanowires

We are advancing wireless power transmission through optimized transmitter and detector structures. By balancing transconductance and drive voltage, and employing impedance matching, we aim to maximize power transfer efficiency within the voltage ranges generated by solar harvesting systems.

Our system design addresses critical specifications, including power levels, operating voltage, field plate dimensions, and antenna design (focusing on gain, bandwidth, and loss). Selecting the optimal transmission frequency is central to achieving high performance.

In circuit design, we are developing new process design kits (PDKs) for transmitter and detector circuits. Our device-level optimization targets 100 mm device processing with a focus on minimizing self-heating and ensuring stable temperature performance. Circuit fabrication and characterization can be integrated with photovoltaic systems or function as standalone units.

WP4: Testing and characterisation for long term space performance

Our solar cell testing includes both standard and advanced electrical characterization methods. Standard tests cover EQE (External Quantum Efficiency), E-V (Energy-Voltage) analysis, and performance evaluation under AM0 conditions (25°C, 1361 W/m²).

For advanced characterization, we simulate a wide range of space conditions, with irradiances from 1361 W/m² (similar to Earth orbit) down to 15 W/m² (Saturn levels) and temperatures spanning from +100°C to -175°C.

We also conduct rigorous environmental tests, including standard radiation exposure (1 MeV electrons, total dose of 1×1015cm−21 \times 10^{15} \, \text{cm}^{-2}1×1015cm−2), thermal vacuum testing, and stress testing to replicate the harsh conditions encountered before and during launch.