Photochemical Characterisation of Perovskites to Inform Stability and Sustainability
Lead Research Organisation:
Swansea University
Department Name: College of Engineering
Abstract
Solar energy is a key component of current and future renewable energy. However, analysis of materials requirements for large-scale PV deployment has shown that solar energy production may well be more limited, from a technological and sustainable point of view than initially supposed. Printable Photovoltaics (PPV), which include dye-sensitized, perovskite and organic solar cells, are promising green energy technologies in their infancy, and prime candidates for full lifecycle optimisation to create truly sustainable renewable energy technologies. The remarkable evolution of perovskite-based solar cells (PSCs) during the last few years, reaching certified power conversion efficiencies (PCEs) over 20% and the recent materials developments for organic photovoltaics (OPV) with higher efficiency and enhanced stability have confirmed PPV as an extremely strong candidate for low cost, low embodied energy, performance-competitive PV technology. Currently, international progress in PV research and technology is running at an unparalleled rate, with major contributions from the SPECIFIC group at Swansea University. This involves developing cheaper materials, along with reducing the energy, cost, and time needed to process materials. When these technologies emerge onto the market it is likely that they will be used initially in niche building and product integrated applications. Lifecycle optimisation for these products must include development of end-of-life (EoL) strategies, appropriate design optimisation and substitution of primary and critical resources. Full lifecycle optimisation for circular economy, however, requires further intervention enabling circular flows of PPV materials and products through reuse, remanufacturing and recycling.
The overall aim of this project is to develop an understanding of device photophysics and photochemistry to inform development of remanufacturing and material substitution strategies for perovskite devices, resulting in world leading, high impact articles in the premier international journals in the field. This involves studying the replacement of the current materials used in perovskite photovoltaic devices that hinders its commercial viability (e.g. looking at critical materials, toxic materials, toxic solvents used in manufacture). Material substitutions will be characterised by investigated the changes in photovoltaic device performance (J-V data, EQE etc) and film characteristics of individual layers (UV/Vis, photoluminescence, photoluminescence lifetimes, XRD, SEM as appropriate) versus control devices. Additionally, environmental and lifecycle benefits will be quantified through appropriate lifecycle cost analysis. Work into replacing the toxic solvents currently used in device manufacture (DMF, chlorobenzene) is a primary focus.
The overall aim of this project is to develop an understanding of device photophysics and photochemistry to inform development of remanufacturing and material substitution strategies for perovskite devices, resulting in world leading, high impact articles in the premier international journals in the field. This involves studying the replacement of the current materials used in perovskite photovoltaic devices that hinders its commercial viability (e.g. looking at critical materials, toxic materials, toxic solvents used in manufacture). Material substitutions will be characterised by investigated the changes in photovoltaic device performance (J-V data, EQE etc) and film characteristics of individual layers (UV/Vis, photoluminescence, photoluminescence lifetimes, XRD, SEM as appropriate) versus control devices. Additionally, environmental and lifecycle benefits will be quantified through appropriate lifecycle cost analysis. Work into replacing the toxic solvents currently used in device manufacture (DMF, chlorobenzene) is a primary focus.
Organisations
| Description | To this date, the award has allowed us to focus on the development of new solvent systems for the deposition of perovskite solar cells. This thin film, crystalline, photovoltaic material is solution deposited, low cost, but requiring the use of strong solvents. However, the most highly efficient films utilise a particularly harmful solvent, dimethylformamide (DMF). DMF has been placed on the candidate list of substances of very high concern (SVHC) as part of the registration, evaluation, authorisation, and restriction of chemicals (REACH) initiative headed by the European Chemicals Agency. This is expected to impose further restrictions on the industrial use of DMF going forward, as seen with NMP. Our work has developed an initial methodology to assess potential 'green' solvents in terms of the physiochemical properties required for dissolving, holding, and depositing perovskite precursor chemicals. This has allowed us to identify multiple 'green' solvents with at least some capacity for use in perovskites. Several of these solvents were then developed into a series of alternative DMF-free multi-component solvent systems. These solutions are capable of depositing the traditional and well studied perovskite composition (MAPbI3), at an equivalent efficiency to DMF based films. Indications also suggest a slight improvement to the optoelectronic properties of the material, including superior crystallinity and fluorescence emission. A study and characterisation of several candidate solvent systems, with slightly different compositions of the multicomponent system, was conducted and published in the Green Chemistry journal as the article 'Sustainable solvent selection for the manufacture of MAPbI3 perovskite solar cells'. Further to this standalone study, we have worked with colleagues to provide them with novel solvents that may be better suited for their perovskite manufacturing process. These solvents were identified in the initial creation of the solvent selection methodology, funded by this award. This includes the use of gamma-valerolactone, a bio derived solvent, in carbon based screen printed perovskite cells. This replaces the legislated solvent gamma-butyrolactone (GBL), a precursor to GHB. This is particularly advantageous in global research spheres where GBL is heavily regulated. The results of a comparative carbon cell study was published in Energy Technology under the title '?-Valerolactone: A Nontoxic Green Solvent for Highly Stable Printed Mesoporous Perovskite Solar Cells'. |
| Exploitation Route | Further work could include the development of robust methods for assessing the lifecycle impact of such 'sustainable' chemical substitutions, to increase confidence levels in performing such substitutions. At this stage of development there are still plenty of perovskite compositions, increasingly complex in nature, which could benefit from the application of this 'green' solvent engineering methodology. Due to the different requirements of these compositions, tailoring the multicomponent solvent system to synergistically improve performance and sustainability will require longer term studies for each composition (this is a current research aim as the award is still active). Further application of this work is to investigate the possibility of formulating sustainable solvent systems for alternative manufacturing technologies (as proven by our collaboration with carbon based devices). |
| Sectors | Chemicals,Energy |
| Description | As an award in progress the impact in a non academic sense is limited right now to a certain amount of press coverage attained for the paper '?-Valerolactone: A Nontoxic Green Solvent for Highly Stable Printed Mesoporous Perovskite Solar Cells'. This reporting is mainly online based technology/engineering/sustainability news outlets including an article on theengineer.co.uk. In an academic sense, it is still quite early on to judge the overall impact, but the research strand is part of current grant applications with hopes to produce further publications in due course. |
| First Year Of Impact | 2021 |