Harnessing Halogen Bond in Perovskite Solar Cells

Project Information

HaloCell

Grant agreement ID: 101059015

DOI

10.3030/101059015

Project closed

EC signature date 3 October 2022

Start date 1 April 2023

End date 30 September 2025

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 235 737,60

Coordinated by

POLITECNICO DI MILANO
Italy

Periodic Reporting for period 1 - HaloCell (Harnessing Halogen Bond in Perovskite Solar Cells)

Reporting period: 2023-04-01 to 2025-09-30

Summary of the context and overall objectives of the project

It is established that fossil fuels enabled a huge global economic growth although resulted to a fragile equilibrium between fuel prices and economic development, an unsustainable exploitation of the natural resources and prompted the ongoing environmental and societal crisis. Solar-driven energy production is pivotal for glass-architecture buildings, public transportation, domestic/ corporate roof-tops/windows and rural areas (i.e. greenhouses); oriented to EU policies for Decarbonization of the EU building stock and European Green Deal for efficient, clean and cheap energy. In the last 15 years, solution-processable metal halide perovskite solar cell (PSCs) technology, the most prominent alternative to the dominant (95% market stake) 1st generation silicon-based photovoltaics (PVs), has emerged.
To accelerate the integration of cost-effective PSCs in the market, current drawbacks need to be resolved. The Halocell project addressed the three main issues that humper the wide adoption of this new technology: the instability in prolonged environmental exposure (moisture, oxygen, irradiation), the toxic nature of some of the employed metals and iii) material imperfections. A new strategy utilizing supramolecular interactions (fluorine-fluorine interactions, halogen bonging) has been implemented and contributed to novel design principles to stabilize the materials at environmental conditions, compensate their toxicity and control their structural properties on-demand.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The aim of HaloCell project was to investigate new strategies for environmentally benign and stable perovskites with tuneable structure and properties. During project’s implementation new organic chemical compounds have been synthesized and characterized by spectroscopic, thermal, microscopic and crystallographic techniques to validate their structure, purity and stability. Then, were tested as building blocks to produce novel advanced hybrid organic-inorganic metal halide perovskites. The ability to form new metal halide perovskites, their photophysical properties and their chemical stability have been validated by crystallographic, spectroscopic and thermal techniques. Intense crystallographic characterization allowed the validation of the existence of the anticipated halogen-halogen interactions (fluorine-fluorine interactions, halogen bonding) and their fundamental role to the structure-properties relation. Quantum mechanical studies shed light on the correlation between the structural and electronic properties of the newly developed materials and the impact to the efficiency of light harvesting optoelectronic devices.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

HaloCell generated new scientific knowledge on how to implement new molecular design principles in the field of photoactive metal halide perovskites, based on selective halogen bonding and halogen-halogen interactions (i.e. fluorine-fluorine interactions). It was discovered that fluorine-fluorine interactions furnish low-dimensional metal halide perovskites stable against environmental degradation, while such supramolecular interactions are essential for the emergence of unprecedented liquid crystalline properties and on-demand modulation of the structure-properties relation. This very first example of such metal halide perovskite materials may pave the way towards a new class of perovskite-based soft materials with tailored properties via the controlled interplay between the solid- and liquid-crystalline states of the materials. Further, it was discovered that halogen bonding enables a reversible thermochromism and heat-switchable birefringence in two-dimensional metal halide perovskites. Modulating on-demand the strength of halogen bonds, new functionalities in supramolecular optoelectronic materials and devices can be unlocked. Moreover, it was discovered that the design of organic compounds with tuneable halogen bond donating strength tune the crystalline order and the photophysical properties of the metal halide perovskite materials. Project’s results advance the current state of the art and are available to the community following Open Science principles. Acquiring further funding for research and device demonstration purposes would allow deeper investigation and reinforcement of the technology readiness level.