Thin film - perovskite tandem structures

Photovoltaics (PV) solar cells are one of the key technologies to realise a decarbonised economy and to date > 1 TW of PV systems have been installed globally. However, it is estimated that > 20 TW of PV capacity alone is needed by 2050. While costs have come down dramatically, the PV module cost is typically less than half that of the total system with limited opportunities to further reduce the balance of systems cost. Therefore, the best way to drive the overall costs down is by increasing the module conversion efficiency. Multi-junction (tandem) solar cells (excluding III-V semiconductors) are offering the next breakthrough opportunity for mainstream terrestrial applications with the prominent solution currently based on the combination of silicon (making use of existing manufacturing capabilities) with perovskite achieving a power conversion efficiency of > 29 %.

Opportunities for thin film based tandem devices remain high due to their low fabrication costs, lightweight and flexible nature making them ideally suited for building integrated PV and mobile devices. State-of-the-art thin film/perovskite devices are approaching ~ 26 % efficiency. This project will focus on key technological aspects of the thin film-perovskite tandem structure:

1. Alternative transparent layer(s) in both the perovskite and thin film cell to reduce film roughness and allow for large flexible devices.

2. Investigate alternative ultra-thin bottom cell (variable bandgap).

3. Lift-off methods for transferable and inverted structures.