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The market for polycarbonate (PC), a versatile material, is growing rapidly. Despite its widespread use in many applications, poor chemical resistance and roughness have hindered its adoption as a substrate in solar cell technologies. Here, the first‐ever perovskite solar cell (PSC) is demonstrated on PC films. A solution‐processed planarizing layer is developed using a commercial ambient‐curable refractory resin through blade coating which decreased film roughness from 1.46 µm to 23 nm, lowered water vapor transmission rates (WVTR) by a half, and significantly improved solvent resistance enabling deposition of precursor inks. The PSCs are fabricated on the planarized PC substrate, with a customized ITO electrode with an average visible transparency of 78%, sheet resistance of 25 Ω/sq, and a safe bending radius of 20 mm. The power conversion efficiency (PCE) reached 13.0%. The unencapsulated PSCs retained 80% of initial PCE after 1776 h upon ISOS‐D‐1 shelf‐life tests. These results open new pathways for integrating solar cells in many products made from PC materials, such as ID cards, smart cards, windows, skylights, buildings, and product packaging, as well as introducing a new solution for planarization and solvent barrier that can be used for other types of optoelectronic devices (LEDs, transistors, etc.) and substrates. [ABSTRACT FROM AUTHOR]

The mass production of photovoltaic (PV) devices requires fast and reliable characterization methods and equipment. PV manufacturers produce a complete module roughly every 20 s, and the electrical performance assessment is typically completed in less than 1 s. Times are even more stringent during cell manufacturing. To be competitive in the PV market, perovskite solar cells and modules aim to the same target, i.e., fast and reliable quality assessment. This communication report discusses the limit of characterizing the current perovskite technology. Standard current vs voltage measurements are compared to maximum power point tracking (MPPT), and a fast MPPT procedure is developed to meet the highly demand standard for quality control in the industry of PV production. [ABSTRACT FROM AUTHOR]

Efficient semi‐transparent solar cells can extend the adoption of photovoltaics beyond standard utility‐scale, commercial, or residential applications. Halide perovskites are particularly suitable in this respect owing to their tunable bandgap. The main drawbacks in the development of transparent perovskite solar cells are the high open‐circuit voltage (Voc) deficit and the difficulties in depositing high‐quality thin films over large area substrates, given the low solubility of bromide and chloride precursors. In this work, passivation strategies are developed for the high bandgap Br perovskite able to reduce charge recombination and consequently improve the Voc. The study demonstrates 1 cm2 perovskite solar cells with Voc up to 1.73 V (1.83 eV Quasi Fermi Level Splitting) and a PCE of 8.1%. The average visible transmittance (AVT) exceeds 70% by means of a bifacial light management and a record light utilization efficiency (LUE) of 5.72 is achieved. Moreover, the potential use of the technology is evaluated toward Internet of Things (IoT) application owing to a bifaciality factor of 87% along with 17% PCE under indoor lighting. Finally, the up‐scaling is demonstrated by fabricating 20 cm2 active area modules with PCE of 7.3% and Voc per cell up to 1.65 V. [ABSTRACT FROM AUTHOR]

Perovskite solar cells, known for high efficiency and compatibility with various photovoltaic (PV) applications, have garnered significant attention from academia and industry. Scaling up these cells conventionally involves fabricating modules with series‐connected cells using a monolithic interconnection based on the P1‐P2‐P3 scheme, a common approach for thin‐film PV modules. The Geometrical Fill Factor (GFF), representing the ratio between active area and aperture area, typically ranges from 90% to 95%. This study introduces an advanced laser manufacturing process to minimize interconnection area by reducing scribe width and minimizing distances between them, achieving an interconnection width of 45 µm with a GFF of 99.1%. Additionally, a discontinuous P2 design further reduces the dead area to an average of 19.5 µm, resulting in a record GFF of 99.6%. Using this interconnection in a highly efficient p‐i‐n stack, the study demonstrates the feasibility of the discontinuous P2 by fabricating 2.6 cm2 minimodules with an aperture area efficiency of 20.7%. The research highlights how proper design can minimize intrinsic losses during the scaling process from cell to module to a negligible level. Experimental studies, coupled with cell‐to‐module loss simulations and electroluminescence mapping for layer deposition uniformity, provide insights into the potential of the new P2 design. [ABSTRACT FROM AUTHOR]

Metal halide perovskite solar cells being one of the fastest emerging technologies for renewable energy still has to become more industry friendly in a way that will allow using it for thin film modules or tandems with conventional silicon devices. The simplest way to achieve this is to use chemical vapor deposition (CVD) technique for tandem production. In this work, we show a method for a single step production of MAPbI3 films in a simple two‐zone CVD reactor from lead diacetate and methyl‐ammonium iodide powders. Obtained films show highly ordered cubic MAPbI3 phase with a thickness of 400–500 nm, good photoluminescence response and absorption band edge similar to spin‐coated film. We used those films to produce p‐i‐n solar cells with ITO/NiO/MAPbI3/C60/Cu structure. The best cell showed negligible 0.23 % PCE right after the manufacturing but significantly improved to 5.5 % PCE after 8 hours of storage in the dark. The main limiting factor affecting the efficiency is low current density, which we attribute to non‐optimized growth conditions; however, our approach is a first step to a single step CVD deposition of MAPbI3 on any type of substrates including texturized silicon subcells for better overall efficiency [ABSTRACT FROM AUTHOR]

Perovskite solar cells promise to be part of the future portfolio of photovoltaic technologies, but their instability is slow down their commercialization. Major stability assessments have been recently achieved but reliable accelerated ageing tests on beyond small-area cells are still poor. Here, we report an industrial encapsulation process based on the lamination of highly viscoelastic semi-solid/highly viscous liquid adhesive atop the perovskite solar cells and modules. Our encapsulant reduces the thermomechanical stresses at the encapsulant/rear electrode interface. The addition of thermally conductive two-dimensional hexagonal boron nitride into the polymeric matrix improves the barrier and thermal management properties of the encapsulant. Without any edge sealant, encapsulated devices withstood multifaceted accelerated ageing tests, retaining >80% of their initial efficiency. Our encapsulation is applicable to the most established cell configurations (direct/inverted, mesoscopic/planar), even with temperature-sensitive materials, and extended to semi-transparent cells for building-integrated photovoltaics and Internet of Things systems. The instability of perovskite solar cells hinders their commercialization. Here, authors report an industrially compatible strain-free encapsulation process based on lamination of highly viscoelastic semi-solid/highly viscous liquid encapsulant adhesive to reduce thermomechanical interfacial stress. [ABSTRACT FROM AUTHOR]

Photocurrent matching in conventional monolithic tandem solar cells is achieved by choosing semiconductors with complementary absorption spectra and by carefully adjusting the optical properties of the complete top and bottom stacks. However, for thin film photovoltaic technologies at the module level, another design variable significantly alleviates the task of photocurrent matching, namely the cell width, whose modification can be readily realized by the adjustment of the module layout. Herein, this concept is demonstrated at the experimental level for the first time for a 2T‐mechanically stacked perovskite (FAPbBr3)/organic (PM6:Y6:PCBM) tandem mini‐module, an unprecedented approach for these emergent photovoltaic technologies fabricated in an independent manner. An excellent Isc matching is achieved by tuning the cell widths of the perovskite and organic modules to 7.22 mm (PCEPVKT‐mod = 6.69%) and 3.19 mm (PCEOPV‐mod = 12.46%), respectively, leading to a champion efficiency of 14.94% for the tandem module interconnected in series with an aperture area of 20.25 cm2. Rather than demonstrating high efficiencies at the level of small lab cells, this successful experimental proof‐of‐concept at the module level proves to be particularly useful to couple devices with non‐complementary semiconductors, either in series or in parallel electrical connection, hence overcoming the limitations imposed by the monolithic structure. [ABSTRACT FROM AUTHOR]

The efficiency gap between perovskite (PVSK) solar sub‐modules (size ≥200 cm2) and lab scale cells (size ˂1 cm2) is up to 36%. Moreover, the few attempts present in the literature used lab‐scale techniques in a glove‐box environment, reducing its compatibility for further product industrialization. Here, we report a PVSK sub‐module (total area 320 cm2, aperture area 201 cm2, 93% geometrical fill factor [GFF]) fabricated in ambient air by hybrid meniscus coating techniques assisted by air and green antisolvent quenching method. To suppress nonradiative recombination losses, improve carrier extraction and control the PVSK growth on such a large surface, we adopted phenethylammonium iodide (PEAI) passivation and PVSK solvent addiction strategies. The high homogeneous and reproducible layers guarantee an efficiency of 16.13% (7% losses with respect to the small area cell and zero losses with respect to the mini‐modules) and a stability of more than 3000 h according to International Summit on Organic PV Stability, dark storage/shelf life in ambient (ISOS‐D‐1). The sustainability of used methods and materials is demonstrated by the life cycle assessment. The scale‐up operation allows for strong impact mitigation in all the environmental categories and more efficient consumption of the resources. Finally, the economic assessment shows a strong cost reduction scaling from mini‐ to sub‐module (about 40%). [ABSTRACT FROM AUTHOR]

The article offers information on the advancements in perovskite solar cells (PSCs), emphasizing their efficiency improvements over the past decade. Topics include the exploration of various strategies to enhance the quality of the perovskite layer, such as using excess precursors, additives, or passivating agents.

Most thin‐film photovoltaic modules are constructed on soda‐lime glass (SLG) substrates containing alkali oxides, such as Na2O. Na may diffuse from SLG into a module's active layers through P1 lines, an area between a module's constituent cells where the substrate‐side charge transport layer (CTL) is in direct contact with SLG. Na diffusion from SLG is known to cause several important effects in II–VI and chalcogenide solar modules, but it has not been studied in perovskite solar modules (PSMs). In this work, we use complementary microscopy and spectroscopy techniques to show that Na diffusion occurs in the fabrication process of PSMs. Na diffuses vertically inside P1 lines and then laterally from P1 lines into the active area for up to 360 μm. We propose that this process is driven by the high temperatures the devices are exposed to during CTL and perovskite annealing. The diffused Na preferentially binds with Br, forming Br‐poor, I‐rich perovskite and a species rich in Na and Br (Na‐Br) close to P1 lines. Na‐Br passivates defect sites, reducing non‐radiative recombination in the perovskite and boosting its luminescence by up to 5×. Na‐Br is observed to be stable after 12 weeks of device storage, suggesting long‐lasting effects of Na diffusion. Our results not only point to a potential avenue to increase PSM performance but also highlight the possibility of unabated Na diffusion throughout a module's lifetime, especially if accelerated by the electric field and elevated temperatures achievable during device operation. [ABSTRACT FROM AUTHOR]

During the last decade, perovskite solar technologies underwent an impressive development, with power conversion efficiencies reaching 25.5% for single‐junction devices and 29.8% for Silicon‐Perovskite tandem configurations. Even though research mainly focused on improving the efficiency of perovskite photovoltaics (PV), stability and scalability remain fundamental aspects of a mature photovoltaics technology. For n‐i‐p structure perovskite solar cells, using poly‐triaryl(amine) (PTAA) as hole transport layer (HTL) allowed to achieve marked improvements in device stability compared with other common hole conductors. For p‐i‐n structure, poly‐triaryl(amine) is also routinely used as dopant‐free hole transport layer, but problems in perovskite film growth, and its limited resistance to stress and imperfect batch‐to‐batch reproducibility, hamper its use for device upscaling. Following previous computational investigations, in this work, we report the synthesis of two small‐molecule organic hole transport layers (BPT‐1,2), aiming to solve the above‐mentioned issues and allow upscale to the module level. By using BPT‐1 and methylammonium‐free perovskite, max. Power conversion efficiencies of 17.26% and 15.42% on a small area (0.09 cm2) and mini‐module size (2.25 cm2), respectively, were obtained, with a better reproducibility than with poly‐triaryl(amine). Moreover, BPT‐1 was demonstrated to yield more stable devices compared with poly‐triaryl(amine) under ISOS‐D1, T1, and L1 accelerated life‐test protocols, reaching maximum T90 values >1000 h on all tests. [ABSTRACT FROM AUTHOR]

Perovskite Solar Cells (PSCs) have attracted attention due to their low cost, easy solution processability, high efficiency, and scalability. However, the benchmark expensive hole transport material (HTM) 2,2′,7,7′-tetrakis[N, N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-MeOTAD), which is traditionally solution-processed with toxic solvents such as chlorobenzene (CB), dichlorobenzene (DCB), or toluene, is a bottleneck. To address this issue, this work investigates the implementation of Zn(II), Cu(II), or Co(II) tetra-tert-butylphthalocyanines (TBU4-Cu, TBU4-Zn, TBU4-Co), established macrocyclic derivatives whose synthesis and processing inside the devices have been redesigned to be more environmentally sustainable and cost-effective by substituting conventional solvents with greener alternatives such as anisole, propane-1,2-diol, and their mixture, as dopant-free HTMs in planar n-i-p PSCs. The anisole-processed HTMs provided power conversion efficiencies (PCE) up to 12.27% for TBU4-Cu and 11.73% for TBU4-Zn, with better photovoltaic parameters than the corresponding cells made with chlorobenzene for which the best results obtained were, respectively, 12.22% and 10.81%. [ABSTRACT FROM AUTHOR]

This article shows the new insights for stabilizing the p‐i‐n perovskite solar cells (PSCs) and modules based on double cation CsFAPbI3 absorber using CsCl additives. The presence of chlorine in the perovskite crystal structure results in the decrease of the lattice parameters by 0.6 ± 0.06%, in the increase of the bandgap value (+0.018 eV), and charge carrier lifetimes with respect to the undoped one. The champion PSCs based on the CsFAPbI3−xClx absorber show an increase in power conversation efficiency from 18.06% up to 20.13% after Cl doping. The light‐soaking stability of PSCs measured at maximum power point demonstrates impressive increase of the T80 from 1128 h for CsFAPbI3‐based devices to more than 3479 h for CsFAPbI3−xClx ones. It is found that the Cl doping suppresses the formation of lead iodide and pure CsPbI3 induced by decomposition and phase segregation processes only when the perovskite is covered with the C60/BCP electron‐transporting layer (ETL), while in the structure without ETL Cl additive is not effective. Finally, the high potential of Cl‐anion engineering for the perovskite modules (5 × 5 cm2) is demonstrated, which shows promising 17.08% of power conversation efficiency and light‐soaking stability for 1396 h. [ABSTRACT FROM AUTHOR]

Perovskite photovoltaics (PVs) is an emerging PV technology that attracts interest thanks to an unprecedented combination of properties, including the ease of the bandgap tunability. The feasibility to deploy wide bandgap absorbers (>2.2 eV) leading to high average visible transmittance (AVT) is particularly intriguing for building-integrated PVs, in particular for smart windows, façades, and agrivoltaics. However, research on this topic is still at the initial stage, especially concerning the development of scalable deposition techniques. Uniform coverage and morphology control of bromide perovskite film are the main issues to tackle. Herein, a systematic study on the development of FAPbBr3-based semitransparent perovskite solar cell (ST-PSC) is presented by replacing spin-coating as the main deposition technique used for the device fabrication. To tackle this topic, the blade coating technique is employed to obtain a manufacturing flow performed at low temperature in the air environment. The results for the bladecoated device show a power conversion efficiency of 5.8%, AVT of 52.3%, and bifacial factor of 86.5%. Moreover, scalable and uniform FAPbBr3 deposition on 300 cm2 substrates is presented for the first time. The combination of low temperature, scale-up capability, and air processing along with promising PV performances represent a feasible platform for the future exploitation of PSC in building integrated photovoltaic. [ABSTRACT FROM AUTHOR]

Among the emerging photovoltaic technologies, perovskite solar cells (PSCs) are the most promising ones with efficiencies close to crystalline silicon. However, stability and reliability issues are still a limit for future applications of this technology. This manuscript investigates the intrinsic instability of PSCs by focusing on the role of the hole-blocking layer (HBL). PSCs were fabricated employing SnOX and bathocuproine (BCP) as an HBL, and their performances were monitored in time. The two architectures show initial similar performances; hence, they are good candidates for comparison, but they feature different instability phenomena. It is shown that cells fabricated with SnOX present larger instabilities mainly ascribable to open-circuit voltage fluctuations (variations in the short-circuit current are negligible). In contrast, the BCP-based cells are more stable with a marginal increase in their power conversion efficiency that follows the increase in the short-circuit current (while the open-circuit voltage does not change). [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) and modules are driving the energy revolution in the coming photovoltaic field. In the last 10 years, PSCs reached efficiency close to the silicon photovoltaic technology by adopting low-cost solution processes. Despite this, the noble metal (such as gold and silver) used in PSCs as a counter electrode made these devices costly in terms of energy, CO2 footprint, and materials. Carbon-based perovskite solar cells (C-PSCs) and modules use graphite/carbon-black-based material as the counter electrode. The formulation of low-cost carbon-based inks and pastes makes them suitable for large area coating techniques and hence a solid technology for imminent industrialization. Here, we want to present the upscaling routes of carbon-counter-electrode-based module devices in terms of materials formulation, architectures, and manufacturing processes in order to give a clear vision of the scaling route and encourage the research in this green and sustainable direction. [ABSTRACT FROM AUTHOR]

Solar cells transparent in the visible range are highly requested for integration in see‐through photovoltaic (PV) applications such as building glass façades or greenhouse roofs. The development of advanced transparent PV can fully exploit the tandem technology where the top cell absorbs the near‐ultraviolet solar spectrum while the bottom one absorbs the near‐infrared part. Herein, a possible implementation of this tandem PV paradigm, namely, the tandem structure composed of a high‐bandgap halide perovskite solar cell and a low‐bandgap organic solar cell, is considered. Electro‐optical simulation results based on parameters calibrated on experimental data show that an efficiency of 15% can be achieved with an average visible transmittance above 50%. This can be obtained considering the halide perovskite with mixed chlorine and bromine anions, a nonfullerene‐based bulk heterojunction, a well‐calibrated light management, and a three‐terminal configuration of the tandem. [ABSTRACT FROM AUTHOR]

Solar cells (SCs) are the most ubiquitous and reliable energy generation systems for aerospace applications. Nowadays, III–V multijunction solar cells (MJSCs) represent the standard commercial technology for powering spacecraft, thanks to their high‐power conversion efficiency and certified reliability/stability while operating in orbit. Nevertheless, spacecraft companies are still using cheaper Si‐based SCs to amortize the launching costs of satellites. Moreover, in recent years, new SCs technologies based on Cu(In,Ga)Se2 (CIGS) and perovskite solar cells (PSCs) have emerged as promising candidates for aerospace power systems, because of their appealing properties such as lightweightness, flexibility, cost‐effective manufacturing, and exceptional radiation resistance. In this review the current advancements and future challenges of SCs for aerospace applications are critically discussed. In particular, for each type of SC, a description of the device's architecture, a summary of its performance, and a quantitative assessment of the radiation resistance are presented. Finally, considering the high potential that 2D‐materials (such as graphene, transition metal dichalcogenides, and transition metal carbides, nitrides, and carbonitrides) have in improving both performance and stability of SCs, a brief overview of some important results concerning the influence of radiation on both 2D materials‐based devices and monolayer of 2D materials is also included. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) intensity is often used as an indicator of the performance of perovskite solar cells and indeed the PL technique is often used for the characterization of these devices and their constituent materials. Herein, a systematic approach is presented to the comparison of the conversion efficiency and the PL intensity of a cell in both open‐circuit (OC) and short‐circuit (SC) conditions and its application to multiple heterogeneous devices. It is shown that the quenching of the PL observed in SC conditions is a good parameter to assess the device efficiency. The authors explain the dependence of the PL quenching ratio between OC and SC on the cell efficiency with a simple model that is also able to estimate the carrier extraction time of a device. [ABSTRACT FROM AUTHOR]

The impending commercialization of perovskite solar cells (PSCs) is plodding despite the booming power conversion efficiencies and high stabilities. Most high‐performance, stable PSCs are often processed partially with high‐temperature processes, increasing the cost of production and energy payback time. Low‐temperature‐processed PSCs are crucial as they cut down the expenses lowering the barriers to industrial use. In addition, low‐temperature‐processed methods have a wide range of applicability in flexible devices and for tandem applications with other photovoltaic technologies where the temperature budget is limited. Therefore, making stable PSCs under ambient conditions as well as providing low‐cost fabrication techniques is highly desirable. Here, a detailed review is presented on the development of the low‐temperature process strategies for fabricating highly stable PSCs and perovskite solar modules. The effectiveness of low‐temperature processing in various classes of materials is also discussed. First, the authors introduce some major degradation processes in PSCs. Then, the developments and evolving strategies of notable materials using low‐temperature processing routes and a correlation with stability are summarized. A few general trends which are related to stability are also discussed. Overall, this review contributes to a better understanding of the status of low‐temperature‐processed cells and modules. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) are a type of emerging thin‐film photovoltaics, which show a promising potential to catch a major portion of the near future market. However, hazardous waste‐generation and cost‐management of the industrial production are two key issues which need to be addressed in the commercialization process. Herein, a universal coating strategy is introduced by combination of blade and spin coating to realize a zero‐waste‐generation of the perovskite precursor materials for layer‐by‐layer deposition of 3D/2D perovskite films on large‐area substrates with high uniformity and reproducibility. This leads to eliminate 90% and 95% of the materials consumption compared to the conventional spin‐coating for deposition of the 3D and 2D perovskite layers, respectively, without changing of the ink precursor. Large‐area PSCs have been realized by blade–spin/blade coating approach reaching 19.55% photo‐conversion efficiency (PCE) over 0.92 cm2 masked area and >1000 h T90 thermal stability at 85 °C. Fabricated perovskite solar modules via blade–spin/blade deposition have been reached to 18.8% PCE over 10 cm2 active‐area. The economic analysis shows the potential for >90% decrease of the operational expenditure via break‐down of the material costs from 1.99 € m−2 in spin coating method to 0.18 € m−2 in blade–spin/blade coating approach. [ABSTRACT FROM AUTHOR]

Large‐scale solution printing perovskite photovoltaics is one of the key technological advantages in comparison to the manufacturing of wafer‐based solar cells (Si, GaAs, etc.). Herein, all‐slot‐die‐coated perovskite solar cells (PSCs) in p–i–n (inverse) configuration with a process fully performed out of the glove box in ambient conditions are demonstrated. The successful implementation of the approach is demonstrated for devices based on the MAPbI3 and CsFAPbI3 perovskite absorbers with four slot‐die‐coated layers—NiOx/perovskite/PCBM/BCP. Noticeably, the use of Cl‐containing additives MACl and FACl in combination with vacuum quenching is found to be essential for the reproducible and controllable crystallization of the perovskite films. Moreover, vacuum quenching shows beneficial results also for the morphology of thin electron transporting layers—PCBM (40 nm) and BCP (11 nm). Finally, the power conversion efficiency (PCE) of the all‐slot‐die‐coated PSCs reaches the level of >16% for MAPbI3 and >17% for CsFAPbI3‐based devices. Slot‐die coating fabrication is successfully upscaled for minimodules (total active area 2.1 cm2), which demonstrates up to 14.9% of PCE. This result demonstrates the high potential of the slot‐die printing for sheet‐to‐sheet fabrication of PSCs and unravels the specifics for each functional layer in the p–i–n device. [ABSTRACT FROM AUTHOR]

In the ever-increasing energy demand scenario, the development of novel photovoltaic (PV) technologies is considered to be one of the key solutions to fulfil the energy request. In this context, graphene and related two-dimensional (2D) materials (GRMs), including nonlayered 2D materials and 2D perovskites, as well as their hybrid systems, are emerging as promising candidates to drive innovation in PV technologies. The mechanical, thermal, and optoelectronic properties of GRMs can be exploited in different active components of solar cells to design next-generation devices. These components include front (transparent) and back conductive electrodes, charge transporting layers, and interconnecting/recombination layers, as well as photoactive layers. The production and processing of GRMs in the liquid phase, coupled with the ability to "on-demand" tune their optoelectronic properties exploiting wet-chemical functionalization, enable their effective integration in advanced PV devices through scalable, reliable, and inexpensive printing/coating processes. Herein, we review the progresses in the use of solution-processed 2D materials in organic solar cells, dye-sensitized solar cells, perovskite solar cells, quantum dot solar cells, and organic–inorganic hybrid solar cells, as well as in tandem systems. We first provide a brief introduction on the properties of 2D materials and their production methods by solution-processing routes. Then, we discuss the functionality of 2D materials for electrodes, photoactive layer components/additives, charge transporting layers, and interconnecting layers through figures of merit, which allow the performance of solar cells to be determined and compared with the state-of-the-art values. We finally outline the roadmap for the further exploitation of solution-processed 2D materials to boost the performance of PV devices. [ABSTRACT FROM AUTHOR]

High bandgap semitransparent solar cells based on CH3NH3PbBr3 perovskites are attractive for building integration, tandem cells, and electrochemical applications. The lack of control of the CH3NH3PbBr3 perovskite growth limit the exploitation of CH3NH3PbBr3‐based perovskite solar cells. Herein, a post‐treatment is carried out after the initial CH3NH3PbBr3 crystallization based on methylamine gas that drastically enhances the perovskite quality leading to a highly crystalline film with improved average visible transmittance (AVT) close to 56%. Opaque devices showed outstanding results in terms of open‐circuit voltage and power conversion efficiency (PCE) reaching 1.54 V and 9.2%, respectively. These achievements are ascribed to a film with reduced morphological defects and better interface quality and reduced nonradiative pathways. For the first time, the fabrication of semitransparent CH3NH3PbBr3‐based solar cells is demonstrated reaching a maximum PCE equal to 7.6%, an AVT of the full stack device of 52%, and an excellent light stability at maximum‐power point tracking. [ABSTRACT FROM AUTHOR]

Although halide perovskite solar cell (PSC) technology reaches, in few years, efficiencies greater than 25%, the cost‐ceffective perspective is achievable only if scalable processes in real manufacturing conditions (i.e., pilot line and/or plant factory) are designed and optimized for the full device stack. Herein, a full semiautomatic scalable process based on the blade‐coating technique is demonstrated to fabricate perovskite solar modules in ambient conditions. An efficient and stable triple‐cation cesium methylammonium formamidinium (CsMAFA) perovskite is deposited in ambient air with a two‐step process assisted by air and green anti‐solvent quenching. The developed industry compatible coating process enables the fabrication of several highly reproducible small‐area cells on module size substrate with an efficiency exceeding 17% and with high reproducibility. Corresponding reproducible modules (less than 2% variability) with a 90% geometrical fill factor achieve an efficiency larger than 16% and T80 = 750 h in light‐soaking condition at maximum power point and room temperature/ambient after encapsulation. Film deposition properties are assessed by different characterization techniques, namely, scanning electron microscopy, profilometry, UV–vis and photoluminescence (PL) spectroscopy, and PL and electroluminescence imaging. The techniques confirm less defects and local coating variations of the ambient air/bladed devices with respect to the nitrogen air/spinned devices. [ABSTRACT FROM AUTHOR]

Comparisons between different laboratories on long‐term stability analyses of perovskite solar cells (PSCs) is still lacking in the literature. This work presents the results of an interlaboratory study conducted between five laboratories from four countries. Carbon‐based PSCs are prepared by screen printing, encapsulated, and sent to different laboratories across Europe to assess their stability by the application of three ISOS aging protocols: (a) in the dark (ISOS‐D), (b) under simulated sunlight (ISOS‐L), and (c) outdoors (ISOS‐O). Over 1000 h stability is reported for devices in the dark, both at room temperature and at 65 °C. Under continuous illumination at open circuit, cells survive only for few hours, although they recover after being stored in the dark. Better stability is observed for cells biased at maximum power point under illumination. Finally, devices operate in outdoors for 30 days, with minor degradation, in two different locations (Barcelona, Spain and Paola, Malta). The findings demonstrate that open‐circuit conditions are too severe for stability assessment and that the diurnal variation of the photovoltaic parameters reveals performance to be strongly limited by the fill factor, in the central hours of the day, due to the high series resistance of the carbon electrode. [ABSTRACT FROM AUTHOR]

MXenes are a recent family of 2D materials with very interesting electronic properties for device applications. One very appealing feature is the wide range of work functions shown by these materials, depending on their composition and surface terminations, that can be exploited to adjust band alignments between different material layers. In this work, based on density functional theory calculations, how mixed terminations of F, OH, and/or O affect the work function of Ti3C2 MXene is analyzed in detail, covering the whole phase‐space of mixtures. The Ti3C2/CH3NH3PbI3 (MAPbI3) perovskite coupled system for solar cell applications is also analyzed. A strong nonlinear behavior is found when varying the relative concentrations of OH, O, and F terminations, with the strongest effect of the OH groups in lowering the work function, already at a relative amount of 25%. A surprising minimum work function is found for relative OH:O fraction of 75:25, explained in terms of the nonlinear electronic response in screening the surface dipoles. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) represent nowadays a promising starting point to develop a new efficient and low‐cost photovoltaic technology due to the demonstrated power conversion efficiency (PCE) exceeding 25% on small area devices. However, best reported devices suffer from stability issue under real working conditions thus slowing down the race for the commercialization. In particular, the hole transporting material commonly employed in mesoscopic n–i–p PSCs (nip‐mPSCs), namely spiro‐OMeTAD, is strongly corrupted when subjected to temperatures above 70 °C due to intrinsic thermal instability and because of the dopant employed to improve the hole mobility. In this work, the novel use of a copper‐based corrole as HTM is proposed to improve the device thermal stability of nip‐mPSCs under prolonged 85 °C stress conditions. Corrole‐based devices show remarkable PCE above 16% by retaining more than 65% of the initial PCE after 1000 h of thermal stress, while spiro‐OMeTAD cells abruptly lose more than 60% after the first 40 h. Once scaled‐up to large area modules, the proposed device structure can truly represent a possible way to pass thermal stress tests proposed by IEC‐61646 standards and, not less importantly, the high temperature required by the lamination process for panel production. [ABSTRACT FROM AUTHOR]

Metal halide perovskites have raised huge excitement in the field of emerging photovoltaic technologies. The possibility of fabricating perovskite solar cells (PSCs) on lightweight, flexible substrates, with facile processing methods, provides very attractive commercial possibilities. Nevertheless, efficiency values for flexible devices reported in the literature typically fall short in comparison to rigid, glass‐based architectures. Here, a solution‐processable fullerene derivative, [6,6]‐phenyl‐C61 butyric acid n‐hexyl ester (PCBC6), is reported as a highly efficient alternative to the commonly used n‐type materials in perovskite solar cells. The cells with the PCBC6 layer deliver a power conversion efficiency of 18.4%, fabricated on a polymer foil, with an active area of 1 cm2. Compared to the phenyl‐C61‐butyric acid methyl ester benchmark, significantly enhanced photovoltaic performance is obtained, which is primarily attributed to the improved layer morphology. It results in a better charge extraction and reduced nonradiative recombination at the perovskite/electron transporting material interface. Solution‐processed PCBC6 films are uniform, smooth and displayed conformal capping of perovskite layer. Additionally, a scalable processing of PCBC6 layers is demonstrated with an ink‐jet printing technique, producing flexible PSCs with efficiencies exceeding 17%, which highlights the prospects of using this material in an industrial process. [ABSTRACT FROM AUTHOR]

The [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) planar system was used to functionalize the phthalocyanine ring aiming at synthesizing novel electron‐rich π‐conjugated macrocycles. The resulting ZnPc−BTBT and ZnPc−(BTBT)4 derivatives are the first two examples of a phthalocyanine subclass having potential use as solution‐processable p‐type organic semiconductors. In particular, the combination of experimental characterizations and theoretical calculations suggests compatible energy level alignments with mixed halide hybrid perovskite‐based devices. Furthermore, ZnPc−(BTBT)4 features a high aggregation tendency, a useful tool to design compact molecular films. When tested as hole transport materials in perovskite solar cells under 100 mA cm−2 standard AM 1.5G solar illumination, ZnPc−(BTBT)4 gave power conversion efficiencies as high as 14.13 %, irrespective of the doping process generally required to achieve high photovoltaic performances. This work is a first step toward a new phthalocyanine core engineerization to obtain robust, yet more efficient and cost‐effective materials for organic electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

The operation of halide perovskite optoelectronic devices, including solar cells and LEDs, is strongly influenced by the mobility of ions comprising the crystal structure. This peculiarity is particularly true when considering the long‐term stability of devices. A detailed understanding of the ion migration‐driven degradation pathways is critical to design effective stabilization strategies. Nonetheless, despite substantial research in this first decade of perovskite photovoltaics, the long‐term effects of ion migration remain elusive due to the complex chemistry of lead halide perovskites. By linking materials chemistry to device optoelectronics, this study highlights that electrical bias‐induced perovskite amorphization and phase segregation is a crucial degradation mechanism in planar mixed halide perovskite solar cells. Depending on the biasing potential and the injected charge, halide segregation occurs, forming crystalline iodide‐rich domains, which govern light emission and participate in light absorption and photocurrent generation. Additionally, the loss of crystallinity limits charge collection efficiency and eventually degrades the device performance. [ABSTRACT FROM AUTHOR]

In the renewable energy field, the use of hybrid perovskite materials has opened up new directions to fabricate cost‐effective and highly efficient photovoltaic devices. Despite impressive power conversion efficiency (PCE), exceeding 25.2%, demonstrated on lab‐scale devices, scalability and stability of device are still topical issues. In this context, large‐area deposition procedures and automated fabrication protocols are required to achieve high throughput serial production of modules and panels. In this work, a spray‐coated tin oxide (SnO2) layer processed at low temperature for the realization of planar perovskite solar cells (PSCs) and modules is demonstrated. Using sprayed Np‐SnO2 as the electron transport layer (ETL), a CH3NH3PbI3‐based solar device shows a maximum PCE of 16.77% (avg. 15.01%) comparable to 17% (avg. 15.5%) with respect to spin‐coated Np‐SnO2. Unencapsulated spray‐ and spin‐coated PSCs stored in 25 °C and 50% relative humidity show shelf life stability by retaining 85% of the initial PCE value after more than 1000 h. Moreover, the feasibility of fabrication of the modules with 15 cm2 active area is demonstrated, which reaches 9.37% of PCE from uniform spray‐deposited SnO2 film on a large area (20 × 20 cm2). [ABSTRACT FROM AUTHOR]

Resonant semiconductor nanoparticles (NPs) that improve both light trapping and scattering have recently emerged as an additional tool for enhancing the efficiency of perovskite solar cells. Among the various types of nanostructures, silicon NPs, which support Mie modes and have lower losses compared with metallic particles with plasmon resonances, exhibit the best improvement for standard methylammonium lead iodide (MAPbI3)‐based solar cells. Herein, not only the optical problem of solar cell optimization with silicon nanoantennas is studied, but also the effects related to charge carrier transport in the presence of NPs are considered. In particular, it is theoretically shown that the silicon nanoantennas can be further optimized by p‐doping. The experimental verification is conducted for MAPbI3‐based solar cells by p‐doped silicon NPs in a hole transport layer (Spiro‐OMeTAD). The improved generation rate of charge carriers and hole transport through the doped silicon NPs leads to improved efficiency of the device. [ABSTRACT FROM AUTHOR]

Previous reports have observed a direct relationship between the polymer poly(3-hexylthiophene) molecular weight (MW) and the perovskite solar cell (PSC) efficiency. Herein, we analyse how the differences in MW and the differences in energetic disorder influence the interfacial carrier losses in the PSCs under operation conditions and explain the observed differences. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'. [ABSTRACT FROM AUTHOR]

• Analytic expressions for solar cell characteristics are presented for limiting cases. • Open circuit voltage is determined by bulk or interface recombination. • Carrier mobility is a key parameter to determine between operation regimes. • Analytic models can help to determine the operation regime of a solar cell. For a detailed understanding of solar cell operation and optimization it is necessary to know how the main performance parameters (open circuit voltage, short circuit current and fill factor) depend on material and structural parameters. In this work, we give analytic formulas for the case of solar cells consisting of a single layer absorber, derived from the drift-diffusion model under some simplifying assumptions. We provide insight into the dependency of these parameters on mobility, light intensity, contact workfunctions and recombination coefficients, and we derive simple formulas for limiting cases. [ABSTRACT FROM AUTHOR]

In the framework of the research on dye-sensitized solar cells of p-type (p-DSCs) the definition and optimization of the electrolyte have been a crucial aspect for the reach of the recent records of photo-conversion for these devices. At the basis of this progress there was the replacement of the redox shuttle of reference I3 -/I- with opportune redox mediators which deliver higher photocurrents and produce larger open circuit photovoltages. In the present study we intend to optimize the composition of the iodine-based electrolyte for p-DSCs employing variable concentrations of redox shuttle. Beside the general conditioning of the overall performance, the analysis of the influence of p-DSC electrolytes has concerned the aspects of the extent of optical parasitic absorption of the electrolyte, of the chemical aggressiveness of the redox species and of the control of the phenomena of electronic back-donation by the photoreduction product. Non-obvious correlations have been found between the main cell parameters (η, JSC, VOC, FF) and the electrolyte conductivity. In the present work, a photocurrent density higher than 4.0 mA*cm-2 is reported when I-based electrolyte (LiI 1.0 M and I2 1.0 M in ACN) was employed. EIS experiments proved that this outstanding photocurrent was due to the lowering of recombination phenomena. [ABSTRACT FROM AUTHOR]

The use of low-band-gap polymers as donors is a new approach to realize high-efficiency polymer solar cells. Among the low bandgap polymers, poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2- b;4,5- b′]dithiophene-2,6-diyl- alt-[4-(2-ethylhexyl)-3-fluorothieno[3,4- b]thiophene]-2-carboxylate-2-6-diyl} (PTB7-Th) is one of the most promising candidates, thanks to the possibility of exploiting deposition protocols (technique, solvent, concentration) from the most-known poly{[4,8-bis(2-ethylhexyloxy)benzo(1,2- b:4,5- b′)dithiophene]-2,6-diyl- alt-[4-(2-ethylhexyl)-3-fluorothieno[3,4- b]thiophene]-2-carboxylate-2-6-diyl} (PTB7) and the fact that it shows a power conversion efficiency (PCE) exceeding 10 %. In this paper, we focus on the role of the ink concentration for film deposition and the formation of the active layer. The effect of the solid content (PTB7-Th:[70]PCBM; [70]PCBM=[6,6]-phenyl-C71-butyric acid methyl ester) in an ortho-xylene-based solution on the performance of the polymer solar cell was investigated. Further, a correlation between the solid content and the1,8-diiodooctane additive in the ink formulation with respect to device performance was discussed. A remarkable PCE of 8.2 % was demonstrated. [ABSTRACT FROM AUTHOR]

The electron transport layer (ETL) plays a fundamental role in perovskite solar cells. Recently, graphene-based ETLs have been proved to be good candidate for scalable fabrication processes and to achieve higher carrier injection with respect to most commonly used ETLs. Here, the effects of different graphene-based ETLs in sensitized methylammonium lead iodide (MAPI) solar cells are experimentally studied. By means of time-integrated and picosecond time-resolved photoluminescence techniques, the carrier recombination dynamics in MAPI films embedded in different ETLs is investigated. Using graphene doped mesoporous TiO2 (G+mTiO2) with the addition of a lithium-neutralized graphene oxide (GO-Li) interlayer as ETL, it is found find that the carrier collection efficiency is increased by about a factor two with respect to standard mTiO2. Taking advantage of the absorption coefficient dispersion, the MAPI layer morphology is probed, along the thickness, finding that the MAPI embedded in the ETL composed by G+mTiO2 plus GO-Li brings to a very good crystalline quality of the MAPI layer with a trap density about one order of magnitude lower than that found with the other ETLs. In addition, this ETL freezes MAPI at the tetragonal phase, regardless of the temperature. Graphene-based ETLs can open the way to significant improvement of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Three different pyran based dyes were synthesized and tested for the first time as photosensitizers of NiO based p-type dye-sensitized solar cells (p-DSSC). The molecules feature a similar molecular structure and are based on a pyran core that is functionalized with electron acceptor groups of different strength and is symmetrically coupled to phenothiazine donor branches. Optical properties of the dyes are deeply influenced by the nature of the electron-acceptor group, so that the overall absorption of the three dyes covers the most of the visible spectrum. The properties of devices based on the NiO electrodes sensitized with the investigated dyes were evaluated under simulated solar radiation: the larger short circuit current density exceeded 1mA/cm² and power conversion efficiency as high as 0.04% could be recorded. The performances of the fabricated p-DSSC have been compared to a reference cell sensitized with P1, a high level benchmark, which afforded a photoelectrochemical activity similar to the best example of our pyran sensitized devices (Jsc = 1.19 mA* cm-2 and α = 0.049%). [ABSTRACT FROM AUTHOR]

A new series of KuQuinones (KuQs) have been synthesized and employed as dye-sensitizers for NiO-based p-type dye-sensitized solar cells (p-DSSCs). KuQs are pentacyclic quinoid compounds which are characterized by a fully conjugated structure that is responsible for the strong and broad absorption in the visible spectrum. The HOMO/LUMO states of KuQs considered here have matching energy levels with the upper edge of the NiO valence band and I−/I3− redox potential energy. These features render such compounds suitable for NiO sensitization in p-DSSCs. The new carboxylic acid-substituted KuQ derivatives proposed here differ in the length of the alkyl chain. The JV characteristic curves and the external quantum efficiency spectra have been recorded. The results showed that the performances of KuQ-sensitized cells were similar to that of the benchmark sensitizer erythrosine B (Ery B), despite the lack of electronic conjugation between the anchoring group and the light absorbing unit. This result led us to hypothesize that the photoinduced charge transfer between the excited KuQ dyes and the NiO electrode occurred through space and not via chemical bonds as it usually occurs in these systems. The mechanism of charge transfer through space has been supported by data from IR spectroscopy. [ABSTRACT FROM AUTHOR]

There are numerous theoretical approaches to estimating the power conversion efficiency (PCE) of organic solar cells (OSCs), ranging from the empirical approach to calculations based on general considerations of thermodynamics. Depending on the level of abstraction and model assumptions, the accuracy of PCE estimation and complexity of the calculation can change dramatically. In particular, PCE estimation with a drift-diffusion approach (widely investigated in the literature), strongly depends on the assumptions made for the physical models and optoelectrical properties of semiconducting materials. This has led to a huge deviation as well as complications in the analysis of simulated results aiming to understand the factors limiting the performance of OSCs. In this work, we intend to highlight the complex relation between mobility, exciton dynamics, nanoscale dimension, and loss mechanisms in one framework. Our systematic analysis represents key information on the sensitivity of the drift-diffusion approach, to estimate how physical parameters and physical processes bind the PCE of the device under the influence of structure, contact, and material layer properties. The obtained results ultimately led to recommendations for putting effort into certain properties to get the most out of avoidable losses, presented the impact and importance of modification of material properties, and in particular, recommended to what degree the design of new material could improve OSC performance. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) are demonstrating great potential to compete with second generation photovoltaics. Nevertheless, the key issue hindering PSCs full exploitation relies on their stability. Among the strategies devised to overcome this problem, the use of carbon nanostructures (CNSs) as hole transporting materials (HTMs) has given impressive results in terms of solar cells stability to moisture, air oxygen, and heat. Here, the use of a HTM based on a poly(3-hexylthiophene) (P3HT) matrix doped with organic functionalized single walled carbon nanotubes (SWCNTs) and reduced graphene oxide in PSCs is proposed to achieve higher power conversion efficiencies (η = 11% and 7.3%, respectively) and prolonged shelf-life stabilities (480 h) in comparison with a benchmark PSC fabricated with a bare P3HT HTM (η = 4.3% at 480 h). Further endurance test, i.e., up to 3240 h, has shown the failure of all the PSCs based on undoped P3HT, while, on the contrary, a η of ≈8.7% is still detected from devices containing 2 wt% SWCNT-doped P3HT as HTM. The increase in photovoltaic performances and stabilities of the P3HT-CNS-based solar cell, with respect to the standard P3HT-based one, is attributed to the improved interfacial contacts between the doped HTM and the adjacent layers. [ABSTRACT FROM AUTHOR]

The technology of perovskite-based solar cells is evolving rapidly, reaching certified power conversion efficiency values now exceeding 20 %. One of the main drawbacks hindering progress in the field is the long-term stability of the cells: the mixed halide perovskites used in most devices are sensitive to humidity and degrade on a timescale varying from hours to weeks. The degradation mechanisms are poorly understood, but likely arise from combined physical and chemical modifications at the nanometer scale. The characterization of pristine and degraded materials is difficult owing to their complex chemical and physical structure and their relatively poor stability. In this work, we investigated the changes in local composition and morphology of a standard device after 2 months of air exposure in the dark, using scanning transmission electron microscopy (STEM) with nanometer resolution for imaging and analysis. Because of a state-of-the-art technique that combines STEM and energy dispersive X-ray spectroscopy (EDX), and the use of different decomposition algorithms for multivariate analysis, we highlighted the migration of elements across the interfaces between the layers comprising the device. We also noticed a morphological degradation of the hole-transporting layer (HTL), representing one of the main factors enabling the infiltration of moisture in the device, which results in reduced performance. [ABSTRACT FROM AUTHOR]

Interface engineering is performed by the addition of graphene and related 2 D materials (GRMs) into perovskite solar cells (PSCs), leading to improvements in the power conversion efficiency (PCE). By doping the mesoporous TiO2 layer with graphene flakes (mTiO2+G), produced by liquid-phase exfoliation of pristine graphite, and by inserting graphene oxide (GO) as an interlayer between the perovskite and hole-transport layers, using a two-step deposition procedure in air, we achieved a PCE of 18.2 %. The obtained PCE value mainly results from improved charge-carrier injection/collection with respect to conventional PSCs. Although the addition of GRMs does not influence the shelf life, it is beneficial for the stability of PSCs under several aging conditions. In particular, mTiO2+G PSCs retain more than 88 % of the initial PCE after 16 h of prolonged 1 sun illumination at the maximum power point. Moreover, when subjected to prolonged heating at 60 °C, the GO-based structures show enhanced stability with respect to mTiO2+G PSCs, as a result of thermally induced modification at the mTiO2+G/perovskite interface. The exploitation of GRMs in the form of dispersions and inks opens the way for scalable large-area production, advancing the possible commercialization of PSCs. [ABSTRACT FROM AUTHOR]