Periodic Reporting for period 2 - MAESTRO (MAking pErovskiteS TRuly explOitable)
Periodo di rendicontazione: 2019-11-01 al 2022-04-30
MAESTRO focusses on perovskites, a material shown in the last 10 years to have revolutionised solar power with the potential to do the same for display technology. Perovskites are a class of compounds with the same crystal structure type as CaTiO3, called the perovskite structure. Hybrid organic-inorganic perovskites, including Pb or Sn halides, are widely used in solar cells and light emitting diodes. Perovskite solar cells offer significant advantages: they are potentially low cost, simple to manufacture and possess exceptional optoelectronic properties leading to efficient light harvesting and emission. A schematic diagram of perovskite film fabrication by solution processing is shown in the image © Matt Klug, Oxford Photovoltaics.
An increasing number of companies, a mixture of multinationals and start-ups, is commercialising this technology, mainly in solar power but also in display technology. Despite their promise, perovskites are far from their full potential. Further progress is limited by low stability (lifetimes are much less than 25 years offered by silicon cells, the industry standard), by their environmental impact (many perovskites used in devices contain lead) and by the need to upscale their manufacture without sacrificing the high efficiency seen in the small cells made in the lab.
MAESTRO’s objective is to generate new skills, knowledge and innovation in the exploitation of perovskite materials for optoelectronics with a focus on solar power and efficient lighting. To achieve this objective an intersectoral and multidisciplinary network of 10 academic and 7 industrial partners was created with members from 9 EU and Associated countries. Early Stage researchers (ESRs) were hired by each partner. ESRs investigated means of prolonging cell lifetimes, reducing cell toxicity and upscaling manufacturing whilst maintaining the exceptionally high power efficiencies for the solar cells that have attracted worldwide attention. Exploitation was considered at all stages from laboratory to fabrication. MAESTRO’s cross sector and cross disciplinary research allowed the students to develop skills and experience, giving them a wide range of career options. Training was provided in science and technology across physics, chemistry, materials science, electrical engineering. Transferable skills were developed in planning, teamwork, communications, information technology, organization, leadership and the skills needed for innovation, such as understanding markets, product life cycles, business models and return on investment.
Information on partners, research, training and outreach activities along with YouTube videos could be found on https://maestro-itn.eu and twitter feed @MAESTRO_ITN.
An increasing number of companies, a mixture of multinationals and start-ups, is commercialising this technology, mainly in solar power but also in display technology. Despite their promise, perovskites are far from their full potential. Further progress is limited by low stability (lifetimes are much less than 25 years offered by silicon cells, the industry standard), by their environmental impact (many perovskites used in devices contain lead) and by the need to upscale their manufacture without sacrificing the high efficiency seen in the small cells made in the lab.
MAESTRO’s objective is to generate new skills, knowledge and innovation in the exploitation of perovskite materials for optoelectronics with a focus on solar power and efficient lighting. To achieve this objective an intersectoral and multidisciplinary network of 10 academic and 7 industrial partners was created with members from 9 EU and Associated countries. Early Stage researchers (ESRs) were hired by each partner. ESRs investigated means of prolonging cell lifetimes, reducing cell toxicity and upscaling manufacturing whilst maintaining the exceptionally high power efficiencies for the solar cells that have attracted worldwide attention. Exploitation was considered at all stages from laboratory to fabrication. MAESTRO’s cross sector and cross disciplinary research allowed the students to develop skills and experience, giving them a wide range of career options. Training was provided in science and technology across physics, chemistry, materials science, electrical engineering. Transferable skills were developed in planning, teamwork, communications, information technology, organization, leadership and the skills needed for innovation, such as understanding markets, product life cycles, business models and return on investment.
Information on partners, research, training and outreach activities along with YouTube videos could be found on https://maestro-itn.eu and twitter feed @MAESTRO_ITN.
This overview shows how MAESTRO succeeded in prolonging cell lifetimes, reducing cell toxicity and upscaling manufacturing to enable exploitation whilst maintaining the exceptionally high efficiencies. It is not exhaustive, for further results see the publications.
a) Tandem solar cells. Perovskites show promise in tandem cells, stacked single cells each of which is formed from a semiconductor of different bandgap energy. Each cell absorbs a different region of the solar spectrum, to increase overall efficiency. MAESTRO showed bandgap tunability of the perovskite layer is needed for these cells, such as from mixed lead‐tin perovskites. Procedures for the fabrication of silicon-perovskite tandem cells that avoid damaging the structure and causing degradation were also tested.
b) Degradation. MAESTRO ESRs unravelled the degradation mechanisms of perovskites that harvest the sunlight to create electrons and holes responsible for the photogenerated current and of the semiconductors used for the electron and hole transport layers sandwiching the perovskite layer. To aid degradation studies, ESRs showed how to identify the internal processes that govern the operation of these devices, such as charge accumulation mechanisms or slow dynamics. Intensity-modulated electroluminescence spectroscopy was demonstrated as a novel technique to characterize optoelectronic devices, deciphering the nature of the working mechanisms by their association with light emission. Multiscale modelling provided deep insights into the properties of point and extended defects in perovskites, in particular to ion migration under pressure. Other examples are identifying the impact of C60 and compact-titania as electron transport layers on device performance, and developing an advanced engineering strategy focusing on the electron transport layer/perovskite interface optimization. MAESTRO also demonstrated mechanisms through which water modifies the properties of halide perovskites. A double-cation perovskite (replacing the unstable methylammonium cation) was demonstrated
c) Upscaling. For upscaling it is necessary to increase the areas of devices. Low efficiencies of devices with areas exceeding 1 square cm stem from a poor understanding of the widespread spatial heterogeneity in devices. MAESTRO outputs include employing luminescence imaging to reveal millimeter-scale heterogeneities in the inferred electronic properties. MAESTRO ESRs demonstrated the development of printable out of glovebox CsFA perovskite solar cells and modules, avoiding more conventional spin-coating technique and antisolvent methods. Flexible substrates were shown to allow the possibility of new applications and increasing production throughput. Leaching out of lead (Pb) ions into the environment presents potential public health risks. MAESTRO showed that thiol-functionalized nanoparticles provide an economic way of minimizing Pb leaching in the case of PSC module damage and subsequent water exposure. A study of the economic cost of using low work exposure limit solvent was also conducted to assess solvent viability for commercial use.
a) Tandem solar cells. Perovskites show promise in tandem cells, stacked single cells each of which is formed from a semiconductor of different bandgap energy. Each cell absorbs a different region of the solar spectrum, to increase overall efficiency. MAESTRO showed bandgap tunability of the perovskite layer is needed for these cells, such as from mixed lead‐tin perovskites. Procedures for the fabrication of silicon-perovskite tandem cells that avoid damaging the structure and causing degradation were also tested.
b) Degradation. MAESTRO ESRs unravelled the degradation mechanisms of perovskites that harvest the sunlight to create electrons and holes responsible for the photogenerated current and of the semiconductors used for the electron and hole transport layers sandwiching the perovskite layer. To aid degradation studies, ESRs showed how to identify the internal processes that govern the operation of these devices, such as charge accumulation mechanisms or slow dynamics. Intensity-modulated electroluminescence spectroscopy was demonstrated as a novel technique to characterize optoelectronic devices, deciphering the nature of the working mechanisms by their association with light emission. Multiscale modelling provided deep insights into the properties of point and extended defects in perovskites, in particular to ion migration under pressure. Other examples are identifying the impact of C60 and compact-titania as electron transport layers on device performance, and developing an advanced engineering strategy focusing on the electron transport layer/perovskite interface optimization. MAESTRO also demonstrated mechanisms through which water modifies the properties of halide perovskites. A double-cation perovskite (replacing the unstable methylammonium cation) was demonstrated
c) Upscaling. For upscaling it is necessary to increase the areas of devices. Low efficiencies of devices with areas exceeding 1 square cm stem from a poor understanding of the widespread spatial heterogeneity in devices. MAESTRO outputs include employing luminescence imaging to reveal millimeter-scale heterogeneities in the inferred electronic properties. MAESTRO ESRs demonstrated the development of printable out of glovebox CsFA perovskite solar cells and modules, avoiding more conventional spin-coating technique and antisolvent methods. Flexible substrates were shown to allow the possibility of new applications and increasing production throughput. Leaching out of lead (Pb) ions into the environment presents potential public health risks. MAESTRO showed that thiol-functionalized nanoparticles provide an economic way of minimizing Pb leaching in the case of PSC module damage and subsequent water exposure. A study of the economic cost of using low work exposure limit solvent was also conducted to assess solvent viability for commercial use.
There were 44 papers and counting that describe these results and that reviewed the subject along with many conference papers. Dissemination to the public took place through a webinar on renewable energy June 2020 and the Perovskite Research Seminar organised by the ESRs linked to the 13th International Online Conference on Hybrid and Organic Photovoltaics (HOPV21), May 2021. The MAESTRO Coordinator took part in an invitation only session on clean energy at the MSCA European Green Deal Cluster event June 2021, presenting a short video on MAESTRO and taking part in a panel discussion. In September 2021, Vivek Babu, a MAESTRO ESR, gave a pitch at the MSCA Falling Wall Lab competition on the use of perovskites for preventing wildlife extinction. ESRs also contributed to dissemination through activities for the public organised by the universities and firms where they were based.