Engineering Stable, efficient perovskite solar cell

This project aims to resolve a critical issue facing perovskite solar cells: their instability under actual operating conditions where cells are subjected to diurnal (day-night) cycling. Over the diurnal cycle,changes in the electrochemical potential within the cell result in the movement of mobile ionic species. As these ions move through the perovskite material—and migrate into other layers that make up the solar cell—they can cause the cell to degrade by triggering decomposition of the perovskite material; corroding the contacts; and potentially causing delamination of the cell layers. 

While it is clear that mobile ionic species cause degradation, the link between ion migration and perovskite cell stability has yet to be fully determined. Critically, the most commonly-used testing regimes do not reflect real-world operating conditions and hence do not accurately evaluate stability. This project aims to systematically and rigorously evaluate strategies to prevent cell degradation due to ionic movement and to understand and prevent the instability of perovskite solar cells under operating conditions where cells are subjected to diurnal cycling.

Durable Silicon Perovskite Tandem Photovoltaics

This project aims to improve the durability of perovskites for silicon (Si)-perovskite tandem photovoltaics for the technology to be cost effective. Silicon (Si)-perovskite tandem photovoltaics have shown huge potential in efficiency gains given the rapid increase in performance from 14% (uncertified) in 2015 to 29% (certified) in 2020, surpassing the efficiency record of single junction Si solar cells. While the market is willing to pay a premium for power generated by Si-perovskite tandem with higher efficiency, long lifetime is critical to guarantee the same or lower levelised-cost-of-energy for manufacturers to invest in tandem-cell technology.

This project consists of four work packages:

  1. chemical analyses of perovskite and Si-perovskite test structures and cells by gas chromatography in conjunction with mass spectrometry (GC-MS) to identify degradation products and thereby underlying degradation mechanisms

  2. spatial luminescence imaging and high-throughput in-situ temporal characterisation of both un-encapsulated and encapsulated perovskite and Si-perovskite test structures and cells to elucidate degradation pathways

  3. development of low cost glass-glass bonding encapsulations and electrical feedthroughs compatible with Si-perovskite tandem to eliminate degradation

  4. exploration of chemically- or phase-stable perovskite alternatives such as perovskite quantum dots (QD) for Si-perovskite tandem.

This project aims to establish measurement protocols for:

  1. gas chromatography–mass spectrometry (GC-MS)

  2. high-throughput current-voltage measurement and statistical analyses

  3. optical-bandgap, luminescent-intensity and absorptivity imaging of perovskites and Si-perovskite tandem cells at different stages of environmental stress.

The project will also increase knowledge of cell degradation mechanisms by identifying:

  1. decomposition products and reactions

  2. key drivers for electrical performance drop

  3. weak spots in cell design and encapsulation.

Finally, the project will establish research capability and capacity to maximise Si-perovskite-tandem durability by developing cell design and encapsulation strategies, such as development of polymer-free glass-glass bonding with hermetic electric feedthrough and the verification phase and optical stabilities of perovskite QD for Si-perovskite-tandem.

Stable Perovskite Modules Under Real-World Conditions

This project aims to improve the durability and reliability of perovskite solar modules under partial shading conditions.

Current perovskite modules can be highly susceptible to damage from partial shading which is a common occurrence during operation, causing permanent damage due to local heating, electrical reverse bias or current flow. There is, therefore, a need to develop strategies to address this challenge and develop partial shading tolerant perovskite modules.

The project will fabricate different perovskite cells and modules using a wide range of materials and cell structures. It will experimentally investigate their properties and performance during and after reverse biasing (due to partial shading). Sophisticated computational modelling will be employed to support the experimental work and to understand what happens inside the cells during reverse biasing. This will include understanding the relationship between material composition, cell structure and partial shading tolerance to improve performance.