Periodic Reporting for period 4 - HY-NANO (HYbrid NANOstructured multi-functional interfaces for stable, efficient and eco-friendly photovoltaic devices)
Okres sprawozdawczy: 2024-01-01 do 2024-06-30
The growing demand of energy imposed by our society is significantly affecting our everyday life and the environment. Europe is active with concrete actions in sustaining alternative ways to supply electricity aiming at reaching the sustainable development goals set by the United Nation 2030 Agenda. Currently, renewable resources are the only option that offers a sustainable production of electricity. In particular, the solar energy emerged from different summits as the most efficient and cost-effective approach, showing the largest annual growth among renewables (from IEA report). The solar cell technology is dominated by the crystalline silicon industry, governed by Asiatic companies. However, even silicon technology has shown limits towards the terawatt deployment of solar energy, particularly in the availability of certain key materials and in the high environmental impact (which translates in long energy payback time). In parallel, the pandemic situation showed the importance of keeping the European know-how and localizing manufacturing to protect the business, providing continuity of technology deployment. For these reasons, it is imperative to sustain emerging technologies in the solar field. HY-NANO deals with one of those: Perovskite solar cells (PSCs), considered one of the big things in optoelectronic research today. Thanks to a worldwide effort, the steady improvement of the cell performance has been achieved. The power conversion efficiency (PCE) reached nowadays records beyond 26%, in line with the best of the crystalline silicon technologies. PSCs give their name to the ABX3 crystallographic structure typical of perovskite materials. The monovalent A-site cation can be either organic or inorganic, the B-site divalent cation is mostly Pb, while the X-site anion is a combination of halides (iodide and bromide mostly, chloride in minor part). The chemical composition of the halide perovskite dictates the optoelectronic properties, which follow the typical behavior of inorganic semiconductors, characterized by a band structure. The great performances achieved by PSCs are due to unique features, such as a high absorption coefficient (which allows for extremely efficient photons harvesting in less than a micron-thick film), great tolerance to defects (which reduces the voltage losses), and bandgap engineering (which enables different device architectures and applications, like tandem configurations). In addition to these fundamental properties, PSCs can be processed by solutions, making the technology cost-effective and at low Co2 footprint, appealing for the market. However, such technology suffers today of poor device reproducibility and stability, being sensitive to water, moisture and oxygen, which limit its operational durability, retarding its commercial uptake. HY-NANO main goal has focused on the smart design of the perovskite material composition and dimensionality as well as device interface engineering, which strongly affect device stability- creating new building blocks of efficient and stable solar cells. Interface engineering is key to that, where judicious choice of material function and energetics is crucial to reduce the losses and concomitantly boost device efficiency and stability. The project is intimately multidisciplinary in nature, calling for approach ranging from material design and synthesis to material characterization in terms of optical properties (i.e. band gap, radiative losses), electronic structure, to interface engineering and rationale device fabrication, characterization and optimization. The main results have demonstrated how engineering innovative multi-dimensional hybrid interfaces with new functionalities emerging from different dimensionality joined together (i.e. 2D/3D combining stability and efficiency) and resulting from the synergistic effects at their interface is key in pushing device efficiency and stability. More in details, the key issue we solved are i) boost device efficiency controlling perovskite chemical structure, thin film morphology and optimizing the interface processes (ultimately minimizing the non-radiative losses and defect density). As output, we demonstrated world record efficiency for inverted Perovskite Solar Cells, a milestone in the field that posed our research at international level. ii) improve the material and device stability, mainly by introducing low dimensional (or 2D) perovskites, tuning the structure from ABX3 to RAn-1BnX3n+1, resulting in a more stable crystalline structure. As main output we demonstrate 40 days of operational stability measured under critical outdoor testing. This is utmost to close the time to market gap for this technology, providing a springboard for their market uptake; iii) reduce the toxicity risks by manipulating perovskite composition but also creating new encapsulation strategy to prevent the possible leakage of toxic elements. As output of this research my team has first developed a highly sensitive low cost lead sensor able to quantify the potential losses of toxic element. Second, my team has developed novel polymeric encapsulants which enabled a wide and edge encapsulation, making the device stable to damp heat stability test. Overall, my team and I hit the target of efficient and stable solar cells, reaching approximately 25% of stability, as the ambitious goal settled in the project plan, and 40 days of outdoor stability, a milestone in the field. The results obtained proved a successful research strategy, advancing the fundamental knowledge on this class of materials with impact in solar cells but also beyond, i.e. in high tech optoelectronic field. In addition, the results of the project are having a Hughe technological impact. Indeed, the project results attracted the attention of big European industry working in the field (such as ENI or ENEL). Finally, the communication of our results to broader general audience, made of general public, stakeholders and policy makers, revealed being very effective, with important implications on the awareness of HYNANO research topic and results on the society, especially in terms of solar energy, carbon footprint and the urge for a more sustainable energy power systems.
The research work performed during the whole period of the grant accomplishes the project plan as in the Description of Action (DoA) of the HY-NANO project. Since July 2019, when I started my ERC HYNANO project, I have been appointed Associate Professor at the HI where I established the pvsquared2 team and I lead my ERC HY-NANO laboratories and project. The project execution has called for a multidisciplinary team I put together aiming to advance in both material design and characterization, interface engineering and rationale device fabrication, and characterization. This enabled to target the ambitious goal of the project in a timely manner, demonstrating how the smart engineering of innovative multi-dimensional hybrid interfaces with new functionalities emerging from different dimensionality joined together lead to efficient and stable solar cells. I na nutshell, the key scientific advances of the project are: i) boosting device efficiency controlling perovskite chemical structure, thin film morphology and optimizing the interface processes (ultimately minimizing the non-radiative losses and defect density). As output, we demonstrated world record efficiency for inverted Perovskite Solar Cells, a milestone in the field that posed our research at international level (published in Science Advances in 2021). ii) the rational design of low dimensional (or 2D) perovskites, tuning the structure from ABX3 to RAn-1BnX3n+1, resulting in a more stable crystalline structure which enabled the fundamental understanding of the material properties and interface stability. As main output we publish a comprehensive work on that (published in Nature Energy in July 2024). iii) 40 days of demonstrated operational stability measured under critical outdoor testing, those relevant for a real device exploitation (manuscript submitted in June 2024). This is utmost to close the time to market gap for this technology, providing a springboard for their market uptake. iii) reduce the toxicity risks by manipulating perovskite composition and creating new encapsulation strategy to prevent the possible leakage of toxic elements. As output of this research my team has first developed a highly sensitive low-cost lead sensor able to quantify the potential losses of toxic element. Second, my team has developed novel polymeric encapsulants which enabled a wide and edge encapsulation, making the device stable to damp heat stability test. Overall, my team and I hit the target of efficient and stable solar cells, reaching approximately 25% of stability, as the ambitious goal settled in the project plan, and 40 days of outdoor stability, a milestone in the field.
The planned objectives of the project have been successfully achieved, in line with what proposed in the Work packages and described in the DoA. For each of the objectives, significant advances have been made. In particular:
-WP1) aiming at exploring new cations and new 2D perovskites to stabilize the perovskite crystal structure and to optimize the optoelectronic properties and bandgap. We have designed novel 2D perovskite materials including fluorinated ones (T1.1) and we evaluated their optical properties (T1.3) and stability (T1.4) [see publications n. 11, 12 and 13]. In addition, we have explored new 2D perovskites and revealed their incredible tunability in terms of material band gap, by simple halide substitution, also revealing a nanoscale phase segregation happening behind this class of materials, which can be adopted for solar cells but also extended into novel high impact optoelectronic applications such as light emitting devices [see Zanetta et al. Adv. Mater. 2022, 34, 2105942]. Moreover, the tunability of 2D perovskite has been pushed to the extreme, manipulating the structural arrangement of the inorganic chain and their directional growth, leading to a new fundamental understanding on the crystallization mechanism behind 2D growth (publication submitted and patent pending). In addition, we screened lead-free perovskite (T1.2) [See publications n. 14 and Pisanu et al. J. Mater. Chem. A, 2020, 8, 1875, n 24] and we developed new lead-free perovskites in the form of Silver/Bismuth Double Perovskites where we found un unprecedented physical behavior, which contrasts with Pb-based perovskites, with a dominant excitonic effects. The large Stokes shift observed is explained by the inherent soft character of the double-perovskite lattices, rather than by the often-invoked band to band indirect recombination [see Pantaler et al. JACS Au 2022, 2, 136]. In addition, the group have deeply investigated the issues derived to the use of toxic elements, resulted in two publications upon invitation [see publications n. 6 and 8] (WP2). Photophysical studies (T1.3) revealed the exception physics behind the layered structure, such as the Stark Effect unveiled for the first time [see publication n. 9]. In addition, the team has also developed a unique set-up for the detection of Photoluminescence signal, its decays (with ps resolution) and its quantum yield (PLQY, essential to test a good working material with minimal radiative recombination). The results appeared in [Pica et al. Struct. Dyn. 2022, 9, 011101, publication n 22], which demonstrated the combined skills of the HY-NANO team and the exploitation of my previous expertise in optical spectroscopy, now transferred to the group. In addition, the team contributed in understanding the fundamental exciton polariton characteristics of such materials (see publication n. 30). Regarding material stability (T.1.4) specific work has been conducted on material characterization by means of combined techniques such as PLQY and Absorption upon aging, X-Ray Diffraction of the fresh and aged materials, combined with full device characterization that enables a clear understanding on the degradation paths under thermal stress [See publication n. 4]. Additionally, we have also contributed to the understanding behind the photostability of 2D and quasi2D perovskites and we identified a critical oxygen concentration in the surrounding environment that affects the mechanism and strongly enhances the rate of layered perovskite photodegradation [see Udalova et al. ACS Applied Materials & Interfaces 2022, 14, 961]. Based on the work here investigated, as reference material, the 3D perovskite has been optimized (T.1.5) serving as a material control, which is also used for our reference device (WP2). We used the material developed in WP1 for the development of the 2D/3D stack interfaces (T2.1) along with the characterization of the photophysical processes therein (T2.2) [see publications n. 10 and 15]. The material characterization discussed in WP1 also applies to the interfaces, for which the understanding of photophysical processes and interfacial losses is crucial [see Pica et al. Struct. Dyn. 2022, 9, 011101] (WP3). Also, different stability tests have been carried out on the materials and interfaced developed, which manifest directly in highly performing devices, as shown by the results in WP3. The interface developed in WP2 have been used for the realization of perovskite solar cells, with a special focus at the beginning on carbon-based perovskite solar cells [see publications n. 4 and 7, at later stage also on nip perovskite solar cells as well as pin solar cells. In particular, we studied the long-term evolution of the interface (T2.3). We revealed that the small cation for the 3D layer can migrate to the 2D top layer and altering its structure over time. By playing with the 2D perovskite material, we show that this migration can be blocked improving the cell lifetime. Such findings provide a deep understanding and delineate precise guidelines for the smart design of multidimensional perovskite interfaces for advanced PVs [see publication n. 15]. The understanding on the interface stability is crucial for the device operation, as well as the response of the material under accelerated thermal stress [see publication n. 10].
- WP3.) Device fabrication, development and optimization has been the core of the HY-NANO project. Considering the current state of the art for the development of both nip and pin perovskite solar cells, our strategy has been to implement and fabricate both standard (nip) perovskite solar cells, using a metal oxide as electron transporting material (ETM) and spiroOMeTAD as hole transporting material (HTM) as well as inverted (pin) devices where the perovskite is interfaced between a polymeric (HTM) and fullerene layer (as ETM). Upon building the lab facility from scratch, we first dedicated to nip solar cells (counting on my previous experience in the field). Upon two years of intense optimization, the team was able to fabricate efficient and reproducible solar cells with power conversion efficiency (PCE) around 22% for triple cation based solar cells and approaching 25% for FAPbI3 based devices [under review] fulfilling (T3.1) and the final ambitious goal of the project. More in details, the project results demonstrate concomitant boost of device efficiency and stability [see publications 26, 31 and 33] obtained by a careful optimization of the device interfaces (i.e. by introducing atomically thin graphene flake to boost electron transport and charge carrier injection) and by the implementation of new 2D cation both in the bulk and on the surface of the 3D perovskite. A careful understanding of the role of the 2D in passivating both bulk and surface defects allows for pushing device open circuit voltage while simultaneously improving the device stability [see in particular papers n.31 32 and 33]. Full device characterization (T.3.2) has been essential for the rational optimization of the device. Within these tasks, in particular, working on nip devices, we have developed novel quasi-2D perovskite interfaces (WP2) and devices, along with their full characterization. Such work revealed extremely interesting performances using only Quasi-2D (with high n) perovskites [see publication n. 7], demonstrating their high impact as active layer in working devices. In addition, we have also been working on all inorganic solar cells, using Cs instead of the organic compound, which can be an interesting alternative for a more stable solution (despite critical issues in terms of material processing, such as solubility). A review has been published on this topic [see publication n. 3]. Specific effort on device interface characterization (T.3.2) has been the focus of publication n. 16. In this work we studied in depth the interfacial recombination and we discovered the multiple roles of the 2D/3D interface in reducing interface recombination and charge accumulation by forming a local pn junction, which serves as ideal heterojunction for charge separation, reducing their recombination yield. This work has been considered a milestone in the understanding of the interface, as highlighted in E. von Hauff Chem 2021, 7, 1694. In parallel, we have also developed pin solar cells, contributing to analyzing how interface functionalization impacts on both nip and pin structure [see publication n. 5, 31 and 33] and, more specifically, working on pin device optimization. To this regard, the team has worked a lot on the optimization of 2D-cation interfaces inventing a double approach for both perovskite/HTM and perovskite/ETM optimization using strategic steps to incorporate large organic cations at those interfaces. This optimization resulted in the realization of pin devices with efficiency in the best case of 23.7%, setting the new world record for pin device [see publication n. 1]. This result has been highlighted in international press, being of recognized world-level impact for the very high proved PCE. Such work certainly demonstrated the importance of interface engineering (WP2) and paves the way for a new route in pin device realization. Finally, it is also worth mentioning that for our expertise, we have been invited to contribute to a very deep and wide review on current advances in new generation PVs, recently published in [see publication n. 2]. In addition, very recently, I lead a comprehensive article reviewing all the 2D perovskite interface methods and advances, I published in Nature Energy in 2024 (see publication 34). On the other side, specifically on stability, my team has worked on multiple direction, looking at self-healing properties of perovskite materials [see publication n32], as well as evaluating the critical conditions to really have a stable device: the outdoor operation. Indeed, in parallel to lab-aging characterization, we set a 40 days long experiment monitoring the real operation and power output of a nip perovskite solar cell (with efficiency close to 25%). Results (subject of submitted publication) revealed minimal losses in performances for such a prolonged period of measurements under harsh outdoor conditions. This sets a milestone in the field and a proof of concept of the technological relevance of the results produced in the frame of the HYNANO project. Such high stability has been obtained also thanks to the work done by my research team on new encapsulant materials, as goal of WP4.
-WP4.) The team has developed MOF based materials which have been used as nanoparticles embedded in polymeric coatings. Such coatings have been deposited on top – as wide sealing material- of highly efficient perovskite solar cells, showing a remarkable increase in the device stability (publication submitted). In addition, those MOF have been fully characterized, offering the promise for their application beyond photovoltaics (see publications n.19).
Beyond the work done in accordance to HYNANO WP, my team has also contributed in analyzing the cost, in terms of environmental impact and LCOE analysis of the produced technology, which resulted in a high impact publications (n. 27 and 29). This analysis is crucial for a real understanding on the potential of perovskite solar cell (from material design to device recycling) to enter in the near future solar market.
In relationship to the project objectives, the team has demonstrated a significant scientific advances in the field of hybrid perovskites, as testified by the awards obtained by the PI (such as the J. Mater. Chemistry Lectureship 2020) and the team member recognition (best Oral presentation at EMRS congress for Phd student Zanetta), the large number of invited lectures, the participation at international conferences as well as in the communications (see the dedicated website https://pvsquared2.unipv.it(odnośnik otworzy się w nowym oknie) and the communication appeared at National Newspapers and International Web-press released (as detailed below).
The planned objectives of the project have been successfully achieved, in line with what proposed in the Work packages and described in the DoA. For each of the objectives, significant advances have been made. In particular:
-WP1) aiming at exploring new cations and new 2D perovskites to stabilize the perovskite crystal structure and to optimize the optoelectronic properties and bandgap. We have designed novel 2D perovskite materials including fluorinated ones (T1.1) and we evaluated their optical properties (T1.3) and stability (T1.4) [see publications n. 11, 12 and 13]. In addition, we have explored new 2D perovskites and revealed their incredible tunability in terms of material band gap, by simple halide substitution, also revealing a nanoscale phase segregation happening behind this class of materials, which can be adopted for solar cells but also extended into novel high impact optoelectronic applications such as light emitting devices [see Zanetta et al. Adv. Mater. 2022, 34, 2105942]. Moreover, the tunability of 2D perovskite has been pushed to the extreme, manipulating the structural arrangement of the inorganic chain and their directional growth, leading to a new fundamental understanding on the crystallization mechanism behind 2D growth (publication submitted and patent pending). In addition, we screened lead-free perovskite (T1.2) [See publications n. 14 and Pisanu et al. J. Mater. Chem. A, 2020, 8, 1875, n 24] and we developed new lead-free perovskites in the form of Silver/Bismuth Double Perovskites where we found un unprecedented physical behavior, which contrasts with Pb-based perovskites, with a dominant excitonic effects. The large Stokes shift observed is explained by the inherent soft character of the double-perovskite lattices, rather than by the often-invoked band to band indirect recombination [see Pantaler et al. JACS Au 2022, 2, 136]. In addition, the group have deeply investigated the issues derived to the use of toxic elements, resulted in two publications upon invitation [see publications n. 6 and 8] (WP2). Photophysical studies (T1.3) revealed the exception physics behind the layered structure, such as the Stark Effect unveiled for the first time [see publication n. 9]. In addition, the team has also developed a unique set-up for the detection of Photoluminescence signal, its decays (with ps resolution) and its quantum yield (PLQY, essential to test a good working material with minimal radiative recombination). The results appeared in [Pica et al. Struct. Dyn. 2022, 9, 011101, publication n 22], which demonstrated the combined skills of the HY-NANO team and the exploitation of my previous expertise in optical spectroscopy, now transferred to the group. In addition, the team contributed in understanding the fundamental exciton polariton characteristics of such materials (see publication n. 30). Regarding material stability (T.1.4) specific work has been conducted on material characterization by means of combined techniques such as PLQY and Absorption upon aging, X-Ray Diffraction of the fresh and aged materials, combined with full device characterization that enables a clear understanding on the degradation paths under thermal stress [See publication n. 4]. Additionally, we have also contributed to the understanding behind the photostability of 2D and quasi2D perovskites and we identified a critical oxygen concentration in the surrounding environment that affects the mechanism and strongly enhances the rate of layered perovskite photodegradation [see Udalova et al. ACS Applied Materials & Interfaces 2022, 14, 961]. Based on the work here investigated, as reference material, the 3D perovskite has been optimized (T.1.5) serving as a material control, which is also used for our reference device (WP2). We used the material developed in WP1 for the development of the 2D/3D stack interfaces (T2.1) along with the characterization of the photophysical processes therein (T2.2) [see publications n. 10 and 15]. The material characterization discussed in WP1 also applies to the interfaces, for which the understanding of photophysical processes and interfacial losses is crucial [see Pica et al. Struct. Dyn. 2022, 9, 011101] (WP3). Also, different stability tests have been carried out on the materials and interfaced developed, which manifest directly in highly performing devices, as shown by the results in WP3. The interface developed in WP2 have been used for the realization of perovskite solar cells, with a special focus at the beginning on carbon-based perovskite solar cells [see publications n. 4 and 7, at later stage also on nip perovskite solar cells as well as pin solar cells. In particular, we studied the long-term evolution of the interface (T2.3). We revealed that the small cation for the 3D layer can migrate to the 2D top layer and altering its structure over time. By playing with the 2D perovskite material, we show that this migration can be blocked improving the cell lifetime. Such findings provide a deep understanding and delineate precise guidelines for the smart design of multidimensional perovskite interfaces for advanced PVs [see publication n. 15]. The understanding on the interface stability is crucial for the device operation, as well as the response of the material under accelerated thermal stress [see publication n. 10].
- WP3.) Device fabrication, development and optimization has been the core of the HY-NANO project. Considering the current state of the art for the development of both nip and pin perovskite solar cells, our strategy has been to implement and fabricate both standard (nip) perovskite solar cells, using a metal oxide as electron transporting material (ETM) and spiroOMeTAD as hole transporting material (HTM) as well as inverted (pin) devices where the perovskite is interfaced between a polymeric (HTM) and fullerene layer (as ETM). Upon building the lab facility from scratch, we first dedicated to nip solar cells (counting on my previous experience in the field). Upon two years of intense optimization, the team was able to fabricate efficient and reproducible solar cells with power conversion efficiency (PCE) around 22% for triple cation based solar cells and approaching 25% for FAPbI3 based devices [under review] fulfilling (T3.1) and the final ambitious goal of the project. More in details, the project results demonstrate concomitant boost of device efficiency and stability [see publications 26, 31 and 33] obtained by a careful optimization of the device interfaces (i.e. by introducing atomically thin graphene flake to boost electron transport and charge carrier injection) and by the implementation of new 2D cation both in the bulk and on the surface of the 3D perovskite. A careful understanding of the role of the 2D in passivating both bulk and surface defects allows for pushing device open circuit voltage while simultaneously improving the device stability [see in particular papers n.31 32 and 33]. Full device characterization (T.3.2) has been essential for the rational optimization of the device. Within these tasks, in particular, working on nip devices, we have developed novel quasi-2D perovskite interfaces (WP2) and devices, along with their full characterization. Such work revealed extremely interesting performances using only Quasi-2D (with high n) perovskites [see publication n. 7], demonstrating their high impact as active layer in working devices. In addition, we have also been working on all inorganic solar cells, using Cs instead of the organic compound, which can be an interesting alternative for a more stable solution (despite critical issues in terms of material processing, such as solubility). A review has been published on this topic [see publication n. 3]. Specific effort on device interface characterization (T.3.2) has been the focus of publication n. 16. In this work we studied in depth the interfacial recombination and we discovered the multiple roles of the 2D/3D interface in reducing interface recombination and charge accumulation by forming a local pn junction, which serves as ideal heterojunction for charge separation, reducing their recombination yield. This work has been considered a milestone in the understanding of the interface, as highlighted in E. von Hauff Chem 2021, 7, 1694. In parallel, we have also developed pin solar cells, contributing to analyzing how interface functionalization impacts on both nip and pin structure [see publication n. 5, 31 and 33] and, more specifically, working on pin device optimization. To this regard, the team has worked a lot on the optimization of 2D-cation interfaces inventing a double approach for both perovskite/HTM and perovskite/ETM optimization using strategic steps to incorporate large organic cations at those interfaces. This optimization resulted in the realization of pin devices with efficiency in the best case of 23.7%, setting the new world record for pin device [see publication n. 1]. This result has been highlighted in international press, being of recognized world-level impact for the very high proved PCE. Such work certainly demonstrated the importance of interface engineering (WP2) and paves the way for a new route in pin device realization. Finally, it is also worth mentioning that for our expertise, we have been invited to contribute to a very deep and wide review on current advances in new generation PVs, recently published in [see publication n. 2]. In addition, very recently, I lead a comprehensive article reviewing all the 2D perovskite interface methods and advances, I published in Nature Energy in 2024 (see publication 34). On the other side, specifically on stability, my team has worked on multiple direction, looking at self-healing properties of perovskite materials [see publication n32], as well as evaluating the critical conditions to really have a stable device: the outdoor operation. Indeed, in parallel to lab-aging characterization, we set a 40 days long experiment monitoring the real operation and power output of a nip perovskite solar cell (with efficiency close to 25%). Results (subject of submitted publication) revealed minimal losses in performances for such a prolonged period of measurements under harsh outdoor conditions. This sets a milestone in the field and a proof of concept of the technological relevance of the results produced in the frame of the HYNANO project. Such high stability has been obtained also thanks to the work done by my research team on new encapsulant materials, as goal of WP4.
-WP4.) The team has developed MOF based materials which have been used as nanoparticles embedded in polymeric coatings. Such coatings have been deposited on top – as wide sealing material- of highly efficient perovskite solar cells, showing a remarkable increase in the device stability (publication submitted). In addition, those MOF have been fully characterized, offering the promise for their application beyond photovoltaics (see publications n.19).
Beyond the work done in accordance to HYNANO WP, my team has also contributed in analyzing the cost, in terms of environmental impact and LCOE analysis of the produced technology, which resulted in a high impact publications (n. 27 and 29). This analysis is crucial for a real understanding on the potential of perovskite solar cell (from material design to device recycling) to enter in the near future solar market.
In relationship to the project objectives, the team has demonstrated a significant scientific advances in the field of hybrid perovskites, as testified by the awards obtained by the PI (such as the J. Mater. Chemistry Lectureship 2020) and the team member recognition (best Oral presentation at EMRS congress for Phd student Zanetta), the large number of invited lectures, the participation at international conferences as well as in the communications (see the dedicated website https://pvsquared2.unipv.it(odnośnik otworzy się w nowym oknie) and the communication appeared at National Newspapers and International Web-press released (as detailed below).
As reported in detail in the previous section, HYNANO contributed in the progress of the knowledge on perovskite solar cells, critically advancing the state of the art. This has included different aspects of the research: from material design to device implementation, from the development of novel 2D perovskite materials for scope even beyond PVs, to the understanding of new (unexpected) physical-chemical phenomena and the realization of in-house developed spectroscopic systems for advanced optical characterization. The progress made by the results of the whole HYNANO activity goes well beyond the state of the art as testified by the high-impact publications in peer-reviewed Journals (33 plus two submitted) reporting the innovative grade of HYNANO research results, as well as the large number of invited talks the HY-NANO team delivered, leading to wide and effective result dissemination. The progress beyond the state of the art, in full alignment with the objectives described in the project DoA, concerns: 1. Development of new perovskite materials with different dimensionality, different chemical elements, and tunable structure, with a particular emphasis on demonstrating the superior stability of this family of materials, but also their incredible tunability – for instance we could control the nanoscale phase segregation of new 2D perovskites, which can serve as a new platform for light emitting applications. In addition, new perovskite have been designed with no lead opening the path for the research into new nontoxic materials; 2. Design and Engineering of new methods for the interface functionalization, which have included new passivation strategies with large cations for the surface doping and for controlling interface energetics; 3. Understanding of key interfacial physical processes, such as radiative recombination paths, which ultimately control the device open circuit voltage and the device performances; 4. Device Optimization, with the realization of high efficient pin perovskite solar cells and the demonstration of world record device with champion pin PCE of 23.7% and, more recently 25% in nip configuration, hitting the project objective; 5. Development of advanced methodologies for understanding the main physical processes happening at the device scale; 6. pushing the device stability, in accordance with the objectives presented in the DoA while concomitantly limiting the risks associated with the use of toxic elements. Results demonstrated device stability on lab scale by means of prolonged aging tests according to ISOS protocols as well as a 40 days power output stability under outdoor testing, those relevant for a real device exploitation. This result is indeed crucial for the device implementation and commercialization and real know-how exploitation in the market. Results have therefore demonstrated robust scientific feasibility allowing us targeting such ambitious objective. In addition, the development of new encapsulation techniques (including the design of new protective layers with MOF nanoparticles embedded in polymeric matrix) enabled to push device stability while reducing the risks of degradation and possible leakage of toxic elements in the environment, ultimate goal of HYNANO.