Perovskite photovoltaics based on metal halide perovskites is a most promising photovoltaic
technology, but further advance demands improved device stability. Here we show the importance of
perovskite composition engineering by demonstrating long-term stable perovskite solar cells. A high-
throughput robotic approach is used to screen 160 mixed-cation mixed-halide perovskites based on
several optical characterizations, such as UV-vis absorption and photoluminescence spectra. Such
automated big data approaches allow to uniquely identify the most photo-thermal-stable perovskites
under elevated temperature and 1-Sun illumination. Most interestingly, while several perovskite
compositions are found to be stable against high temperatures of up to 140 C and are capable of
passing the damp/heat test without being packaged, the situation is more complex in working devices,
as a stable device requires both - a stable semiconductor layer and stable interfacesi. A p-type interface
consisting of polymeric multi-layers with variable doping is introduced as a robust anode interfaceii.
By integrating the most stable perovskite into this structure, we achieve stable devices that attain
about 100% of their initial efficiency after > 1000 hrs of continuous mpp operation at low
temperatures of 30-40 degrees Celsius. Increasing the temperature to beyond 65 °C caused interface
corrosion, as clearly seen by the formation of s-shaped jV curves. Meticulous engineering of the
dopand / host interactions allowed to overcome this instability, and most recent devices pass up to
2000 hrs under 1 sun @ 65 C without notable degradationiii. Nevertheless, degradation is still
observable when the operation temperature is further raised towards 85 C and above, which
highlights that the microscopic degradation mechanisms in perovskite devices are still not fully
understood. This work introduces into the fundamentals how to accelerate the screening for stable
perovskites layer and devices for operation at elevated temperatures.

REFERENCES:

i Y. Zhang et al and C. J. Brabec , Nature Communication 2021.
ii Y. Hou et al and C. J. Brabec, Science 2017.
iii Y. Zhang et al and C. J. Brabec, Nature Energy 2021, in print.

Engineering interfaces in perovskite solar cells is nowadays paramount in the optimization of multilayer perovskite device stack. This stem true for multi-dimensional (2D/3D) perovskite based solar cells, where high efficiency can be combined with promising device durability. However, the exact function of the 2D/3D interface in controlling the device behaviour and the interface physics therein are still vague.

Here I will discuss the 2D/3D functions which can simultaneously act as surface passivant, electron blocking layer, and driving efficient and selective charge extraction. In particular, I will demonstrate that the exact knowledge on the interface energetics is crucial to obtain for a smart interface engineering. As an example, I will discuss the case of thiophene-based 2D perovskite/ 3D perovskite interfaces forming a p-n junction. This leads to a reduction of the electron density at the hole transport layer interface and ultimately suppress the interfacial recombination. As a consequence, we demonstrate that photovoltaic devices with enhanced fill factor (FF) and open-circuit voltage (VOC) of 1.19V which approaches the potential internal Quasi-Fermi Level Splitting (QFLS) voltage of the perovskite absorber, nullifying the interfacial losses. We thus identify the essential parameters and energetic alignment scenario required for 2D/3D perovskite systems in order to surpass the current limitations of hybrid perovskite solar cell performances. This knowledge turns fundamental for device design, opening a new avenue for perovskite interface optimization. In addition, I will discuss the role of 2D cations versus 2D cation passivation to state the exact role of having a 2D perovskite layer on top if necessary – or maybe not – to push device performances.

The halide perovskite photovoltaic technology can be scaled to large area modules and panels using printing processes and laser patterning. Here, we will present the progresses made to scale up from small area solar cells to modules and panels up to a dimension of 0.5 sqm. By working in controlled atmosphere (Glove Box with nitrogen) and apply conventional spin-coating technique it Is possible to easily scale up from 9 to 140 cm² active area with efficiencies above 20% for the smallest modules and 14.7% for the largest. Specific efforts have been devoted to developing a deposition process out of the glove box (GB) in conventional ambient air. We transfer out of the GB several coating technologies, including blade coating and slot-die. To do this without penalizing efficiency and stability, a specific formulation of perovskite absorber and doping strategies of transporting layer have been formulated together with specific quencing techniques based on air, vacuum and solvents.  These optimizations permitted to realized perovskite solar modules with an efficiency of > 17% on an active area of 43 cm², keeping above 90% of the initial efficiency after 800 h thermal stress at 85 °C.  One of the critical issues scaling the cell to module size is the control of interface properties. We demonstrated that  tuning of interface properties can be successfully obtained by applying two-dimensional (2D) materials, such as graphene, functionalized MoS₂, MXenes as well as 2D Perovskite.  This permitted also to increase the stability of the cell (T80) well beyond 1000h under light soaking and thermal stress tests.

The discovery of a family of semiconductor materials based on the complex halides of group 14 elements opened a big research arena and led to the emergence of a new perovskite photovoltaic technology. Impressive photovoltaic performances were demonstrated for perovskite solar cells based on lead halides, whereas their practical implementation is still severely impeded by the low device operational stability. Most importantly, complex lead halides were found sensitive to both light and heat, which are unavoidable satellites under the realistic solar cell operational conditions. Suppressing these intrinsic degradation pathways requires a thorough understanding of their mechanistic aspects. Herein, we explored the temperature effects in the light-induced decomposition of the model systems represented by MAPbI3 and PbI2 thin films under well-controlled anoxic conditions. We show that decreasing the sample temperature from 55 oC to 30 oC can extend the perovskite lifetime spectacularly by a factor of >10-100 and also alter the material decomposition pathway. The analysis of the aging kinetics revealed that MAPbI3 and PbI2 photolysis have quite high effective activation energies of ~85 and ~106 kJ mol-1, respectively, which explain the observed strong effect of the temperature on the rate of the material photodecomposition. These findings suggest that controlling the temperature of the perovskite solar panels might be a key factor for reaching their long operational lifetimes (>20 years) required for the practical implementation of this promising technology.

Despite the tremendously rapid development of perovskite photovoltaics (PV) in terms of power conversion efficiency (PCE) the stability of such devices typically still does not fulfill the requirements for commercialization of this technology. Up to date, PV devices with carbon-based back-electrodes (CBEs) have demonstrated the longest operational stability, surpassing several IEC 61215 standards [1]. Moreover, recently we reported that such modules could withstand requirements of the IEC hot-spot test (evaluating the stability of PV devices against reverse-bias degradation),[2] which is one of the most crucial hurdles not only for perovskite PV, but even for such well-established PV technology as c-Si. [3] Thus, devices with CBEs represent a promising method for up-scalable manufacturing of stable and low-cost perovskite PV devices.[4,5]

However, besides cost and stability, we must also consider greenhouse gas (GHG) emissions coming from PV manufacturing, which are projected to grow beyond national emissions of countries like France or Germany in the next 10 years.[6] Although the production of perovskite PV with CBEs has the potential to reach the lowest CO₂-footprint limit possible for large scale PV applications,[4] one of the methods to reduce the GHG emissions of PV industry further is the development of effective recycling strategies, where perovskite materials offer unique advantage of liquid processing.

Up to now, only studies on the recyclability and life-cycle-assessments of non-encapsulated devices have been demonstrated. To show that perovskite PV devices with CBEs can not only be stable but also recyclable, we manufactured such solar cells and modules, encapsulated with thermoplastic polyolefin and polyisobutylene edge-seal, which provide sufficient protection against moisture, passing the IEC damp-heat test. [7] Through life-cycle assessment, we show that most of the negative environmental impact comes from the layer deposition, rather than the environmental footprint of material itself, making the re-use of as many layers as possible the most preferable option. We demonstrate an effective mechanochemical method to remove the edge-seal and encapsulant, as well as degraded perovskite and CBEs, leaving metal oxide layers intact making them available for re-use. Our novel recycling method of such devices results in minimal performance loss, which helps to reduce the negative environmental impact of such devices (global warming potential in kg CO₂-eq./kW_p) by > 40%. Such strong reduction in the global-warming potential of perovskite solar modules with CBEs qualifies them as truly sustainable PV technology meeting all requirements for its introduction to the PV market.

Organic-inorganic perovskites have the strong potential to replace the mainstream silicon photovoltaic technology due to their extensive research. The power conversion efficiency (PCE) of perovskite solar cells of just below 26% is advancing to that of silicon photovoltaics. The advancements make it a highly viable technology for broad applications especially building-integrated PVs and Tandems. Nevertheless, the efficiency of these cells is recorded on a small area. Scaling the small area cells into modules with minimal loss is a major challenge to be addressed. We will here, present our work on the optimization strategies of the semitransparent modules to achieve a power conversion efficiency slightly below 15% scaled from the semitransparent cell of 19.7%. The transparent electrode  plays a major role in the performance of the semitransparent module. Our work addresses the challenges in reducing the loss in PCE between small area cells and modules.

Deposition of two-dimensional perovskite layers between perovskite absorber and hole-transporting layer is considered to be an essential strategy to reduce defects in state-of-the-art perovskite solar cells (PSCs). This strategy, however, suffers from the inevitable formation of in-plane favoured two-dimensional (2D) perovskite layers with impaired charge transport, especially under thermal conditions, impeding photovoltaic performance and device scale-up. Therefore, to overcome this limitation, we designed and investigated various cations that form 2D perovskite layers on top of the 3-dimensional perovskite layer. The ensuing PSCs achieve an efficiency of over 24% with long-term operational stability (over 1000 hours). Notably, a record efficiency of 23% for the perovskite module with an active area of 26 cm2 was achieved using compositionally engineered perovskite. In this talk, we will present strategies to enhance PSC's power conversion efficiency and stability.

Halide perovskite solar cells (PSCs) have emerged as a competitive photovoltaic technology with power conversion efficiencies (PCEs) surpassing the 22 % mark. One of the main bottlenecks of the technology is their long-term stability. Understanding the different degradation mechanisms of the constituent materials, as well as interface instabilities, is of crucial importance for commercialization. Semiconductor oxides (SO) constitute a fundamental part of highly efficient photovoltaic technologies such as PSCs. Electron transport semiconductor oxides, like TiO₂, are characterized by an oxygen vacancy (O_vac)-mediated conductivity caused by a deviation in stoichiometry, the presence of impurities, or both. In oxygen-containing atmospheres, and especially under UV light, holes generated at the nonstoichiometric oxide surface react with the oxygen adsorbed at an O_vac increasing charge recombination and degradation of the solar cell. Different methods have been employed to passivate or eliminate these O_vac. For example, the application of organic interfacial modifiers with anchoring groups specifically selected to bond with oxides, or the application of less reactive SnO₂ which results in less hygroscopicity, fewer O_vac at its surface, and less UV-damage. Another possibility is the application of a coating of secondary oxides, like Al₂O_3, applied to supress surface defects, avoid interfacial recombination, and enhance device stability. A less-explored option is the application of complex oxides with singular properties, such as ferroelectric, multiferroic, magnetic, etc. In this talk, we report our most recent studies on the application of classic oxides (binary, doped, nanostructured) and complex oxide compounds (ternary, ferroelectric, etc.) as transport layers in Halide Perovskite Solar Cells. We will discuss their effect on the long-term stability of complete solar cell devices.   

Since the emergence of perovskite photovoltaics in 2009 the scientific community has witnessed steep progress of the technology in terms of solar to electric power conversion efficiency 25.5% accompanied by advancement in addressing stability issues and developing a deeper understanding of fundamental structure-processing-property relationships.

The technology transfer from lab to fab has proven challenging, however merely a decade after discovery the commercialization of organic-inorganic metal halide perovskites in terms of photovoltaic devices is just around the corner.

Many issues had to be tackled to meet industrialization, among them large area deposition techniques, safety standards and material wastage without compromising efficiency and stability. Thus, a cost-effective, reliable fabrication process capable of delivering highly efficient and durable large-area perovskite modules is vital for success of the technology. Saule Technologies has been developing a fully scalable inkjet printing process of perovskite solar cell modules on lightweight flexible substrates. This talk will focus on recent advancements in the technology and the product development process required to bring inkjet printed perovskite modules closer to commercial utility. Our perovskite solar cell solutions offer high power density at low light intensity conditions and at the same time exhibit long lifetime to guarantee autonomous operation for IoT devices far beyond typical battery lifetime. It has been a long but exciting way from the first laboratory samples to the first commercial perovskite solar cell production line. The first applications of hybrid perovskite solar cells will include powering IoT devices and many more will follow soon.

Perovskite solar cells are still improving their high performance in J-V characteristics in various compositions of perovskites including all inorganic materials. The most important element in the J-V performance is open-circuit voltage (Voc) which reflects suppression of charge recombination losses at the interfaces. We achieved high levels of Voc for all inorganic CsPbI₂Br (bandgap 1.9eV) with 1.42 V ¹ and for mixed cation Cs-FA-MAPb(I,Br)₃ perovskite cells (bandgap 1.51eV) with 1.19V.² The CsPbI₂Br device was fabricated by using amorphous SnO_x layer that passivate the perovskite and meso-SnO₂ interface, and enables Voc exceeding 1.1V even under week indoor illumination (200 lx) with power conversion efficiency (PCE) >34%. The mixed cation perovskite cells, working with conversion efficiency >22%, shows Voc close to its SQ limit (ca.1.21V) as a result of interfacial modification with phenyethylamine bromide as a dipole-inducing layer. ² These works show that the successful passivation of the junction interfaces is essential for improving Voc toward application of perovskite photovoltaic cells to circumstances of large light intensity variation. Technologies based on interfacial molecular engineering are expected to improve the device performance of lightweight flexible plastic devices. We employed an organic peroxide, artemisinin (water-insoluble anti-malarial drug), to modify the interface of SnO₂ ETL and multi-cation perovskite (Rb-Cs-FA-MA)Pb(I,Br)₃).³ This redox-active molecule is considered to interreact with the oxide surface and lead cation. The artemisinin-based passivation was applied to the SnO₂-perovskite interface of a plastic film flexible device. The device showed decreased hygroscopicity due to the effect of artemisinin, leading to an increase in shelf life. Its effects of enhancing Voc improved the device efficiency up to 21%. Organic passivators should be chemically and thermally stable non-ionic materials and inactive against their diffusion. Our challenges to design durable passivation materials for Voc improvement are underway.

Ion migration is a well-known problem in perovskite materials. It causes baseline drift, lowers imaging resolution, accelerated decomposition and device performance degradation. In particular in X-ray detectors, the effect of ion migration is more obvious under working bias. The first principals study reveals that the 0D structure perovskite would show effectively reduced ion migration between neighbouring unit cells compared with the popular 2D and 3D perovskites. A nucleation-controlled strategy is developed to grow superior inch-sized high-quality 0D-structured lead-free (CH3NH3)3Bi2I9 perovskite single crystals (MA3Bi2I9 PSCs) with significantly lower ion migration, much reduced dark current and better environmental stability compared to other perovskite materials, enabling us to design and fabricate a new type of 0D-structured lead-free perovskite X-ray detector. It is found that the X-ray detectors show surprisingly high sensitivity, 15 times more than that of the state-of-the-art commercial α-Se detectors, with very low detection limit that is desired for medical diagnostics, material inspection, etc. Furthermore, their response time is as short as 0.98 ms, the shortest among all X-ray detectors reported in literature, which may allow us to develop an X-ray screening system with reduced X-ray dose and improved resolution.

The emergence of metal halide perovskites has revolutionized the field of emerging photovoltaics. Typically, the active layers of perovskite solar cells are deposited either from solution, or alternatively by thermal evaporation. In this talk, I will describe how the two methods can be combined to fabricate highly efficient all-inorganic CsPbI3 perovskite solar cells. Specifically, half of the active layer is deposited by solution processing, following by thermally evaporating the second half. While devices fabricated by each method separately show a reasonable performance of 13-15%, the combination of the two methods leads to perovskite solar cells with improved open-circuit voltage, short-circuit current and fill factor, leading to a maximum photovoltaic performance >20%. Moreover, devices fabricated by this hybrid approach exhibit a significantly reduced hysteresis. We show that the improvement in performance and decrease in hysteresis are associated with a reduced density of defects in the active layers fabricated by the hybrid approach, thus demonstrating its high potential for the fabrication of efficient perovskite solar cells.

Hybrid organic-inorganic perovskites are highly promising absorber materials for third generation photovoltaic technologies. These materials have low production costs and enable solar cell efficiencies comparable to the best crystalline silicon PV cells [1]. The main obstacle for their widespread practical implementation is the low operational stability defined by both external and internal factors. External factors such as the action of oxygen and moisture from the atmosphere can be suppressed by encapsulating the photoactive layer. Intrinsic factors causing degradation of the materials include thermal and photochemical aging effects. In particular, the light-induced decomposition of MAPbI₃ leads to the formation of metallic lead and molecular iodine due to photolysis of PbI₂ [2]. 
Although the degradation mechanisms are usually considered as a bulk property, they are more likely to occur at the scale of individual grains and between the boundaries. Along with this, infrared scattering scanning near-field microscopy (IR s-SNOM) techniques are being actively developed to visualize the cation dynamics in lead halide perovskites [3]. Since changes in the concentration and localization of organic cations have a strong influence on the material optoelectronic characteristics and the solar cells performance, the IR s-SNOM provides great opportunities for experimental investigation of the photochemical degradation processes in these materials with nanoscale spatial resolution. Herein, we applied IR s-SNOM technique for the first time to follow the nanoscale dynamics of the light-induced decomposition of MAPbI₃ films under well-controlled anoxic conditions inside the glove box.
The obtained results revealed that the light-induced aging of the MAPbI₃ films has a spatially heterogeneous character. The perovskite decomposition is started at the grain boundaries and is accompanied by the formation of core-shell structures, where the perovskite grains are covered with a “skin” of PbI₂, which is the MAPbI₃ main aging product. It is shown that lead iodide does not decompose further into metallic lead and molecular iodine under the used experimental conditions (low temperature, LED light). On the contrary, PbI₂ recrystallization with the formation of big flat crystallites is observed. 
To summarize, we demonstrated a high potential of using IR s-SNOM as a method to study the photodegradation of perovskite films with nanoscale local spatial resolution. The application of this technique in combination with other complementary methods represents a promising approach for identifying the most stable absorber material compositions.

Long-term operational stability is a prerequisite for the commercialization of perovskite solar cells. Inorganic perovskite solar cells exhibit a high thermal stability and efficiencies of 20.8 %, which corresponds to 72 % of the Shockley-Queisser limit for the band gap of 1.72 eV [1]. However, the reported PCE is still lower than for organic-inorganic perovskite solar cells, mainly due to lower open-circuit voltages (V_OC). The V_OC of the record inorganic perovskite solar cell with CsPbI_3-xBr_x composition and 1.72 eV band gap is 1.23 V, while organic-inorganic cells of the same band gap reach a V_OC of 1.31 V [2].

This study investigates state-of-the-art inorganic CsPbI₂Br perovskite solar cells to reveal the efficiency potential and the losses induced by each layer. This is achieved by measuring intensity-dependent photoluminescence (PL) of each layer stack. This technique enables us to construct potential JV curves, revealing not only the potential V_OC, but also the potential fill factor [3]. Based on realistic assumptions of the photocurrent, we can therefore calculate the efficiency potential of the solar cell or stack which could be reached by avoiding any transport losses.

For the present study, CsPbI₂Br solar cells in n-i-p and p-i-n configuration are fabricated using an air-annealing procedure specifically developed for this composition. The CsPbI₂Br films have an efficiency potential of 21.6 % when deposited on glass, 20.7 % on MeO-2PACz and 19.9 % on mesoporous TiO₂, suggesting a very low defect density in the CsPbI₂Br perovskite.

In the n-i-p CsPbI₂Br solar cells, losses in QFLS are caused in almost equal parts by the electron transport layer (ETL) and hole transport layer (HTL). In the p-i-n solar cells, the main part of the losses is caused by the ETL. Importantly, both configurations show a strong mismatch between the quasi Fermi level splitting (QFLS) in the perovskite layer and the measured V_OC at the contacts. The inorganic p-i-n solar cell has a QFLS-e∙V_OC mismatch of 170 meV. The organic-inorganic reference solar cell with the same band gap shows a QFLS- e∙V_OC mismatch of only 10 meV. Using ultraviolet photoelectron spectroscopy (UPS) measurements, we examine possible reasons for this striking difference and discuss potential solutions.

Overall, this study helps to identify the most promising layer stacks for inorganic n-i-p and p-i-n perovskite solar cells and reveals the contribution of each interface to the voltage and fill factor losses.

APbX₃ lead perovskites, where A is either an organic (methylammonium MA⁺ and formamidinium FA⁺) or an inorganic (Cs⁺) species, are a highly promising photovoltaic materials, due to the exceptionally high power conversion efficiency (> 25%) demonstrated recently in the case of mixed-cation and mixed-halide perovskites. However, the poor intrinsic stability of complex lead halides remains a major hindrance in the commercialization of this emerging photovoltaic technology. Experimentally it is known, and has been demonstrated by our group that bromide-containing mixed halide perovskites have much lower photostability when compared to the equivalent iodide-based materials. The light-induced photochemical aging produces metallic lead as one of the final decomposition products in the case of all the experimentally studied complex lead halides (MA_0.15FA_0.85PbI_2.55Br_0.45, Cs_0.1MA_0.15FA_0.75PbI_2.55Br_0.45, Cs_0.15FA_0.85PbI_2.55Br_0.45, MA_0.15FA_0.85PbI₃, Cs_0.1MA_0.15FA_0.75PbI₃ )  except for Cs_0.15FA_0.85PbI₃, which demonstrated outstanding stability under white light exposure. To check the effect of the halide substitution our theoretical calculations compared FAPbI₃ with the bromide-containing mixed-halide perovskite FAPbBr_0.45I_2.55 and indicated that hole-coupling drives the formation of interstitial-vacancy halide pair defects to become more thermodynamically favorable, thus leading to the accelerated degradation of the halide-mixed perovskites. It is notable that oxidation of this type is possible also without illumination; however, our calculations demonstrate that illumination greatly promotes it. Our calculations also showed the relative insensitivity of the halide vacancy towards the composition of the perovskite.

Perovskite solar cells (PSCs) have achieved tremendous progress in terms of power conversion efficiencies (PCE) during the last decade which features a high commercialization potential of this PV technology. To achieve high PCE, significant efforts have been made to design and investigate new hole-transport layer (HTL) materials. Along with the spiro-OMeTAD, polytriarylamines (PTAAs) represent one of the most commonly used families of HTL materials [1]. However, even the most promising HTL materials delivering high PCEs will not bring PSCs towards commercialization if their high cost is not taken into consideration [2]. Unfortunately, both spiro-OMeTAD and PTAA are prohibitively expensive materials with the current price of ~500 and ~2000 $/g respectively [3].

Spiro-OMeTAD is expensive due to its multistep synthesis that requires low temperature, sensitive and aggressive reagents, and costly sublimation purification. The high cost of PTAA is driven by both complexity of the utilized synthetic methods, which often require several synthetic steps, and the high cost of metal-based catalysts, including noble metal complexes. For example, Pd-catalyzed Suzuki reaction has been actively utilized as the method of polycondensation of triarylamines with halogen and boron-based functional groups [4]. Unstable and pricey Ni(COD)₂ has also been utilized for the polymerization of brominated triarylamines. Although the oxidative polymerization of arylamines has been actively utilized for the synthesis of materials for electroluminescent devices [5], the application of this approach for the synthesis of HTL materials for perovskite solar cells remains still unexplored.

Herein, we report a straightforward synthesis of a series of polytriarylamines using an efficient and cheap FeCl₃-assisted oxidative polymerization. This simple yet efficient synthetic approach allowed us to obtain a series of polytriarylamines. These polymers outperformed commercial PTAA, which was utilized as a reference, when used as HTL materials in MAPbI₃-based n-i-p perovskite solar cells. In particular, reproducible PCEs of >18% were reached for ITO|SnO₂|PCBA|MAPbI₃|HTL|VO_x|Ag device configuration.

This work was supported by Russian Science Foundation (project 19-73-30020).

Metal-halide perovskites have recently emerged as one of the most promising low-cost promising materials for photovoltaic and light-emitting technologies, due to their excellent optoelectronic properties and fabrication versatility. Since the advent of the first perovskite solar cells (PSCs) in 2009, their power conversion efficiency (PCE) has now reached 25.6% [1], for active areas smaller than 1 cm². Moreover, their operational stability is also constantly improving [2-3]. The interest in transferring the existing technology into large-area perovskite modules using industrial compatible techniques, necessary for industrial development is exploding.

Lately, we have demonstrated highly efficient, large area, planar PSCs where the MAPbI₃ perovskite layer has been deposited by thermal co-evaporation of PbI₂ and MAI. The high-quality co-evaporated perovskite thin films are uniform over large areas showing low surface roughness, and a long carrier lifetime. The high-quality perovskite thin films together with vacuum processed charge transport layers PSCs with PCE above 20% in both n.i.p [4, 5] and p.i.n [6] configurations. The co-evaporated MAPbI₃ guarantee an impressive thermal and environmental stability maintaining over ≈95% and ≈80% of their initial PCE after 1000 and 3600 h respectively under continuous thermal aging at 85 °C without encapsulation. TE_MAPbI₃ PSCs demonstrate remarkable structural robustness, absence of pinholes, or significant variation in grain sizes, and intact interfaces with the HTM, upon prolonged thermal aging.

The first co-evaporated mini-modules achieved record PCEs of 18.13% and 18.4% for active areas of 20 cm² [7] and 6.4 cm² [8].

Moreover, looking forward to tandem integration and building-integrated photovoltaics we have also developed coloured semi-transparent PSCs and mini-modules for all the range of colours realized.

These results represent a significant step towards the development of high-quality large-area perovskite solar cells and mini-modules, one of the main requirements for the commercialization of the technology.

Mixed metal-halide perovskite solar cells (PSC) are advancing in power conversion efficiency (PCE) faster than any other photovoltaic technologies, reaching over 25% [1]. However, the reported record efficiencies are obtained with lab-scale devices. Promoting this technology to the market level with efficient and stable devices manufactured with cost-effective, industrially scalable processes is the persisting challenge. Here we report on bifacial PIN perovskite photovoltaic modules processed on glass,  passing the 1000 hour damp-heat test by retaining 94% of its initial PCE. The same device stack was transferred to a flexible substrate. This resulted in the first flexible, bifacial PIN modules with a state of the art efficiency and passing the 1000 hour damp-heat test by retaining 100% of its initial PCE.

Figure 1: Image of the flexible, semi-transparent bifacial PIN perovskite module with monolithic series laser interconnection.

REFERENCES:

[1] https://www.nrel.gov/pv/assets/pdfs/pv-efficiency-chart.20200203

Halide perovskite solar cells are on the brink of commercialisation with exciting efficiency trajectories for both single junction and tandem configurations. Critical to their commercial success is demonstration of long-term stability, yet our fundamental understanding of failure modes is still lacking. Here, I will show our recent work investigating how nanoscale heterogeneity plays a key role in performance and stability [1]. I will show how nanoscale phase impurities, even at trace levels, lead to carrier traps [2] and critical photo-instabilities in devices. Finally, I will show how phase engineering will be essential to remove these problematic inclusions, ultimately leading to extremely phase and operational stable halide perovskite absorbers and devices.