PROGRAM DAY 2

To be defined.

The fast progress of Perovskite Solar Cells (PSC) on the photovoltaic performance under different lighting conditions, stability, and upscaling demonstrates the great potential of this technology to transit to industrial scale. In particular, the performance of PSC under low-light conditions surpassed already the energy efficiency of the well-established amorphous silicon technology. However, PSC’s industrialization will only be possible if the manufacturing process of the whole device is compatible with large-scale mass production.
Here, we report the design and development of an experimental procedure to fabricate flexible low-cost PSC based on slot-die coating focusing on mass production. The device architecture and the materials were selected to minimize the number of fabrication steps (depositions and treatments), minimize energy consumption (low temperature and no need for high-vacuum) and maximize the stability of the device, without significantly compromising its PCE. The chosen architecture was a 4-layered n-i planar device with metal oxide electron transport material – SnO2, mixed-halide 3D perovskite – (FAPbI3)0.85MAPbBr3)0.15, 2D perovskite capping/passivation layer – n-octylammonium iodide (OAI), and carbon-based electrode (deposited by blade-coating).
The solvent system of each material was carefully selected aiming low viscosity, high volatility and appropriate polarity. The coating window of each material was determined using the viscocapillary model for slot-die technique and the measured rheological data. According to the low flow limit plot, all solutions form a stable meniscus at the specified speed of 1 m min-1. The final optimized manufacturing process produces a PSC with a maximum PCE of 18.6 % under 1000 lux (372 μW cm-2; 0.64 cm2 active area). PSC with bare 3D perovskite kept 96 % of its initial efficiency after 550 h under MPPT under 0.25 sun, which demonstrates that the transition from lab to fab of perovskite technology is definitely not that far in the future.

The breakthrough of perovskite solar cell technology relies on sustainable and low-cost upscaling of large-area modules through innovative processes.

Piezoelectric drop-on-demand inkjet-printing is considered an emerging manufacturing process for the development of perovskite solar cells (PSCs) with low material waste and high production throughput. Until now, all case studies focused on inkjet-printed PSCs have relied on the use of hazardous solvents and/or high-molarity perovskite precursor inks, both of which are known to enable the development of high-efficiency photovoltaics (PVs). The work presented herein provides a new insight for the development of lower toxicity, high-performance and stable (for more than two months in storage) inkjet printable perovskite precursor inks for fully ambient air processed PSCs. The capability of producing high-quality and with minimum coffee-ring defects, annealing-free perovskite absorbent layers under ambient atmosphere conditions is demonstrated using an ink composed of a green low vapor pressure noncoordinating solvent and only 0.8 M of perovskite precursors (more than 2 times lower than the usually applied concentration).
Notably, the PSCs manufactured utilizing the industry-compatible carbon-based hole transport material free design and the proposed ink attain >13% efficiency, which is considered on the performance records for the under-consideration PV architecture employing an inkjet-printed active layer. Outstanding is also the stability of the PV devices under the conditions specified by the ISOS-D-1 protocol (T95 = 1000 h). Finally, the scaling up of the solar cell devices to the mini-module level (100 cm² aperture area) is demonstrated, with the upscaling losses to be as low as 8.3%rel dec-1 per upscaled active area.

Perovskite solar cell (PSC) technology [1] [2] is regarded as a highly promising technology for the generation of solar energy. However, the main impediment to the large-scale commercial utilization of PSCs lies in their sensitivity to moisture, which leads to degradation, with the metal top electrode being the primary source of degradation [3]. As a result, the development of effective solutions to prevent metal electrode-induced degradation is critical to know the full potential of this technology. To address this problem, our work explores a low-temperature n-i-p device architecture that replaces the conventional gold back electrode with a hydrophobic carbon-based electrode on a flexible substrate by blade coating technique. Carbon materials are low-cost starting materials that can be easily processed into carbon electrodes using simple fabrication techniques, and they also have the potential to contribute to the “circular” use of materials [4]. The low-temperature carbon-based PSC concept has numerous advantages, such as the ability to integrate a planar hole transport layer (HTL), better control over perovskite crystallization, and suitability for flexible substrates, roll-to-roll fabrication using scalable deposition techniques like screen printing and inkjet printing, and doctor blade coating. However, the power conversion efficiency of carbon-based PSCs lags behind that of conventional gold-based counterparts due to the inefficient charge transfer and collection associated with carbon electrodes and poor perovskite/carbon interfacial contact. To prevent device degradation, several methods are being used, including optimizing the hole transporting layer (HTL), which is crucial in device operation since it acts as a protective layer for the perovskite absorber layer against environmental influences such as humidity [5]. The aim of this work is to optimize the best hole transporting material that can improve the performance and stability of the device. HTL-free devices were fabricated for comparison, and one of the most interesting inorganic hole transporting materials (HTMs), copper(I) thiocyanate (CuSCN), was used since it combines intrinsic hole-transport (p-type) characteristics with wide band gaps larger than 3.5 eV [6]. At the optimum concentration, a high-power conversion efficiency (PCE) of 7.5% was achieved on a 1 cm² active area device. The obtained results were compared with the performance of gold-based devices using the reference organic HTL, PTAA. The optimization of the HTL material, allowed to demonstrate a significant improvement in the performance and stability of the device, which could pave the way for the large-scale commercialization of PSCs with low environmental impact and cost-effectiveness.

Perovskite solar cells (PSCs) have attracted intensive attention due to the ever-increasing power conversion efficiency (PCE) and simple fabrication process. Particularly, we have developed a triple-mesoscopic architecture for PSCs that can be fabricated via screen printing techniques. The traditional back contact materials of noble metals are replaced by low-cost carbon materials, such as graphite and carbon black. Through optimizing the material compositions, modifying the interfaces, and designing the device structures, the PCE of printable triple-mesoscopic PSCs has increased from the initial ~6% in 2013 to ~over 19% in 2023. Besides the advantages of low material cost and simple fabrication process, printable triple-mesoscopic PSCs also have shown promising stability under various conditions, such as high temperature, continuous illumination, and outdoor conditions.

Fabricating all-ambient perovskite solar cells (PSCs) can reduce production expenses, hence accelerating commercialization of PSC. To fabricate completed PSCs in ambient-air, the conventional Spiro-OMeTAD and metal electrode need to be replaced by ambient-stable materials, including Copper(I) thiocyanate (CuSCN) and carbon electrode. However, moisture can cause formation of non-perovskite phases, resulting in ambient-fabricated perovskite films with high-roughness surface that affects formation of the CuSCN hole-transport layer (HTL). Therefore, we will discuss approaches to form high-quality CuSCN layer in ambient-air, including polymer passivation and various CuSCN deposition process. In addition, we examine the effect of deposition technique for carbon electrode on the adhesion between carbon and CuSCN leading to fabricating all-ambient PSCs with good performance. Ultimately, integration of the perovskite surface passivation and CuSCN HTL integrated with carbon electrode can produce all-ambient PSCs that retain approximately 80% of their initial performance after 2400 hours of storage under 30%RH conditions.

A hermetic encapsulation is required to protect perovskite solar cells (PSCs) from the most relevant sources of degradation – humidity and oxygen [1]. According to the IEC61646 PV standard test, commercial photovoltaic devices must be stable from – 40 °C to 85 °C and relative humidity of 85 % [2]. Therefore, to achieve the previously mentioned requirements, the PSCs should be fabricated with thermally stable layers deposited through scalable deposition methods and protected by a long-term stable hermetic encapsulation. Laser-assisted glass frit encapsulation has successfully achieved long-term stability for PSCs with n-i-p and HTM-free structures [3,4]. The advanced novel dual laser beam glass frit sealing was previously developed and optimized to hermetically encapsulate n-i-p PSCs at 65 ± 5 °C for a short processing time of < 60 s [3]. In contrast, printable HTM-Free perovskite solar cells have been reported to be sealed with a single laser beam at 100 ºC for a long processing time of 35 min [4]. The present work studies the application of dual laser beam sealing to encapsulate HTM-Free PSCs and mini-modules fabricated with (5-AVA)0.05(MA)0.95PbI3 perovskite absorber. The power conversion efficiency (PCE) of the small-area PSCs slightly increased from (8.27 ± 0.83) % to (10.75 ± 1.41) % after the encapsulation process at 65 °C with the dual laser beam method. While using the same procedure for the mini-modules, the average PCE increased from (6.08 ± 0.32) % to (6.61 ± 0.49) % after laser-sealing at 80 °C. In conclusion, this work indicates that dual laser sealing has a low impact on the performance of lab-scale devices and mini-modules. This study concluded that the double laser-assisted glass frit encapsulation is suitable for large-area PSCs. Further intrinsic stability studies towards UV light will be performed to demonstrate the robustness of the glass frit sealing.

Electrodeposition was investigated in this work as a substitute method to develop large area perovskite active layers for carbon-based perovskite solar cells (C-PSCs) application. This innovative perovskite deposition process could pave the way for the industrialization and marketing of carbon-based perovskite solar cells architecture. Indeed, it is a low-cost process, leading to smooth & uniform layers, over large areas. In addition, it is produced under ambient conditions (with no need of glove box), and is environmentally friendly in terms of solvent engineering, since no toxic solvents are needed to stabilize or improve the morphology of the layers obtained. The present study looks at the influence of 5-AVAI (AVAI = ammonium valeric acid iodide) in the fabrication of traditional MAPbI3 perovskite. Several studies have already shown that the addition of this additive improves the stability and performance of carbon perovskite solar cells produced by spin coating or drop casting. However, in the literature, the effect of 5-AVAI has never been studied on cells produced by electrodeposition. The present study therefore involved varying the ratios of MAI: AVAI in the conversion bath in order to study the effect of this additive on C-PSCs realized by electrodeposition. It was noticed that according to MAI:AVAI ratios infiltrated in the perovskite lattice, different microstructures, optical and chemical properties are obtained. The perovskites obtained thus have different bandgap energies, crystallinity rates and stabilities. A correlation will thus be established with the photovoltaic performance of electrodeposited C-PSCs varying with the amount of 5-AVAI.

Carbon-based multi-porous-layered-electrode perovskite solar cells (MPLE-PSC), which use mesoporous carbon as the back electrode, can provide excellent performance stability against high temperature and humidity environments at a low cost. However, the stability of MPLE-PSC under UV light has not yet been improved. This is due to the photocatalytic effect of TiO2, which is commonly used as the electron transport layer of MPLE-PSC. In this study, MPLE-PSC with SrTiO3 as an alternative electron transport layer to TiO2 were fabricated and their UV durability was compared. As a result, the open circuit voltage and fill factor of the TiO2-based solar cell decreased upon UV irradiation, and the performance decreased to 80% of the initial performance after 2 hours. On the other hand, no performance degradation was observed in the solar cell using SrTiO3. Therefore, the SrTiO3 electron transport layer can be proposed as a solution to improve the UV stability of solar cells.

To be defined.

The pursuit of commercializing perovskite photovoltaics has been driving the development of various scalable perovskite crystallization techniques. Among them, gas-quenching has been demonstrated as the most promising crystallization approach due to its capability for high-throughput deposition of perovskite films. However, the perovskite films prepared by gas-quenching assisted blade coating are susceptible to a high number of pinholes, defects, and significant inhomogeneity, owing to the limited understanding of perovskite crystallization behaviour and thus lack of robust methodologies to improve it. Here, we devise in-situ optical spectroscopies integrated into a doctor blading setup that allows to real-time monitor film formation during the gas-quenching process. We first elucidate the essential role of gas quenching treatment in achieving a smooth and compact perovskite film by controlling the nucleation rate. After that, we revisit and unravel, by means of in-situ techniques along with the assistance of phase-field simulations, the role of excessive methylammonium iodide (MAI) in the precursor solution in increasing grain size by accelerating crystal growth rate. Our results show that a tailored amount of excessive MAI is dominantly controlling the growth rate of nanocrystals, which is critical to achieving high-quality perovskite films with improved crystallinity, preferred orientation and reduced defect density. Eventually, fully-printed solar cells with an impressive champion PCE of 19.50% and mini-modules with a PCE of 15.28% are achieved. These results emphasize the growth rate can be optimized independently from the crystal nucleation rate for developing efficient fully printed perovskite photovoltaic.

Printable mesoscopic perovskite solar cells (p-MPSCs) with carbon counter electrode show great potential for commercialization, but little research has been devoted to understanding the dynamics of photogenerated carriers in this type of cell, limiting their further performance improvements. Herein, time-resolved photoluminescence spectroscopy (TRPL) was used to quantify the carrier recombination, diffusion and extraction processes in p-MPSCs. TRPL was performed on mesoscopic samples with different structural configurations, such as single-layer samples with perovskite-filled ZrO2 or TiO2 scaffolds, bilayer samples with carbon electrode on one side. On this basis, the numerical simulation and TRPL differential lifetime diagrams were used to find the relationship between spectroscopy features and carrier dynamics with different incident directions. It is found that the position of the corner position of the step-type curves is very sensitive to the change in the diffusion coefficient, and the carrier diffusion in mesoscopic samples should not be neglected at the time scale monitored by TRPL. The diffusion coefficient was successfully extracted from the TRPL and obtain a long diffusion length of 5.48 µm in a well-crystallized m-ZrO2 sample. This also demonstrates that the hole transport layer is not necessary for p-MPSCs. In addition, the relationship between the maximum quasi-Fermi energy level splitting and the bulk recombination coefficient within perovskite is determined through calculations. This study takes an important step toward establishing the relationship between the mesoscopic structure, spectroscopy features, carrier dynamics, and device performance of p-MPSCs.

Lead-free Hybrid Organic-Inorganic perovskite have gained remarkable interest for photovoltaic application due remarkable electronic, optical, and electrical properties, and their lack of toxicity. In this work, the performance of lead-free formamidinium-Tin-Iodide (FASnI3) based perovskite solar cells C-PSC with ZnO as Electron Transport layer (ETL), and without Hole Transport layer (HTL-free) and C, Cu, Ag, and Ni as back contact materials is simulated using SILVACO TCAD software in MODELAB of CENER institute. The thickness, total defect density, and doping of the absorber layer (FASnI3), as well as the working temperature are varied to investigate their effect on the performance. The solar cell configuration FTO/ZnO/FASnI3/ Carbon have a PCE of 20.66%. These results can pave the way to design of new efficient, cheap lead-free perovskite solar cells with carbon as a back contact.