Flexible perovskite solar cells (PSCs) have gained significant attention for their lightweight and bendable characteristics, making them suitable for diverse applications. The utilization of transparent flexible electrode substrates enhances their flexibility. In this study, we introduced 1,3-bis(diphenylphosphino)propane (DPPP) as an interface layer in the SnO2/perovskite interface to improve surface passivation. The optimization of the front interface resulted in unit cell efficiencies exceeding 23% for rigid substrates and close to 20% for flexible substrates. The lower efficiencies for PSCs on flexible substrates is attributed to the lower current density due to higher light absorption of the PEN/ITO than glass/FTO substrates. The incorporation of DPPP notably reduced surface recombination, leading to a higher open-circuit voltage in these PSCs. We also investigated the P2 line laser scribing parameter for flexible perovskite solar modules, which is crucial for achieving higher fill factors.

Engineering perovskite precursor ink to widen the processing window is crucial to obtaining uniform, compact, and pinhole-free perovskite films at scale using industrially relevant solution coating techniques. Here, we introduce a ternary solvent system and systematically investigate the impacts of coordinating solvents, N-methyl-2-pyrrolidone (NMP) and N,N'-dimethylpropyleneurea (DMPU), on the physical properties of the slot-die-coated perovskite films and on the corresponding device performance. Tailoring NMP and DMPU concentrations in the precursor ink allows us to control the perovskite intermediate phase formation and widen the processing window, enabling the reproducible production of perovskite films with high photoelectrical quality at scale. Using the optimized precursor ink, we demonstrate slot-die-coated perovskite minimodules with power conversion efficiencies of 19 and 16% on 56 and 100 cm2 substrates, respectively.

All‐inorganic perovskite cesium lead triiodide (CsPbI 3 ) with inorganic nature, low‐temperature synthesis, and a suitable bandgap is desirable for high‐performance photovoltaics. However, the scalable production of CsPbI 3 photovoltaics is still challenging due to a large nucleation energy barrier and slow phase transition during unassisted natural crystallization. Here, the crystallization dynamics of CsPbI 3 thin films is tailored via lead acetate (PbAc 2 ) substitution in the perovskite precursor ink, allowing the scalable fabrication of efficient all‐inorganic perovskite solar cells and minimodules. Introducing PbAc 2 enlarges CsPbI 3 colloid size in the precursor and reduces the nucleation energy barrier. Additionally, reactions between acetate and dimethylammonium in the wet film accelerate the removal of dimethylammonium additives and generate solvent vapors for self‐regulate internal solvent annealing, resulting in densely packed, uniform, and pinhole‐free CsPbI 3 perovskite films over large areas. This strategy demonstrates inverted CsPbI 3 solar cells with 20.17% efficiency and good operational stability (retaining 95.5% of initial efficiency after continuous operation for 1800 h) and 15.1%‐efficient CsPbI 3 minimodules with an active area of 26.8 cm 2 .

Despite the remarkable growth of perovskite photovoltaic technology, the performance and stability of flexible perovskite solar modules (f-PSMs) are still below the commercial level, and even the clear reasons for this have hardly been elucidated. Here, we found that flexible perovskite solar cells (f-PSCs) suffer from a trade-off between efficiency and stability due to the off -balance between surface coverage and the charge -transporting property when conventionally using colloidal SnO 2 nanoparticles as an electron -transport layer (ETL). To resolve this trade-off, we newly designed an ETL that enhances the charge transport properties and mitigates the shunt sites, resulting in improved efficiency and operational stability. Therefore, we succeeded in achieving a certified efficiency of 21.8% in f-PSC (22.92% in-house) and 16.4% in f-PSM (900 cm 2 ). Furthermore, we discovered that incomplete coverage gives rise to the formation of a shunt pathway, causing the current crowding effect, which could have a significant impact on long-term operational stability.

Blade coating of perovskite solar cells (PSCs) and modules has progressed considerably toward the industrial production of perovskite photovoltaics. Developing stable perovskite precursors is critical for achieving uniform coating over large areas. Here, the engineering of a perovskite precursor solution consisting of 2‐methoxyethanol (2‐Me) and 1,3‐dimethyl‐imidazolidinone (DMI) with superior intermediate phase stability that enables scalable production of efficient perovskite solar modules is reported. With this perovskite precursor solution, uniform and pinhole‐less perovskite film is deposited over a large area of > 100 cm 2 and higher‐efficiency PSCs and modules are obtained. The best‐performing unit cell and module with n‐i‐p configuration reach power conversion efficiencies of 23.4% and 20.1%, respectively. Additionally, a series of non‐destructive metrology methods, such as spectroscopic ellipsometry, hyperspectral photoluminescence, electroluminescence, and laser beam‐induced current mapping, are employed to assess and guide the development the blade‐coated perovskite modules. This results show that rational engineering of precursor inks for blade coating is promising for the scalable production of efficient perovskite solar modules.

As the efficiency of small-area perovskite solar cells has reached more than 25% in recent years, it is now essential to accelerate the commercialization of perovskite photovoltaics. Developing low-cost, reliable, and automatic large-area coating techniques is a crucial step toward the industrial production of perovskite solar modules. For large-area solution-based deposition of perovskite films, solvent extraction from the wet precursor film is critical to producing pinhole-free, uniform, and high-quality perovskite films. Here, we report a scalable slot-die coating method for perovskite photovoltaic mini-module production. A vacuum quenching technique is developed to assist the formation of a perovskite intermediate phase by extracting solvents from the precursor films uniformly throughout the coating area. We study the impact of N-Methyl-2-Pyrrolidone (NMP) as a coordinating solvent in the perovskite precursor ink on the quality of slot-die-coated perovskite films and the photovoltaic performance of corresponding devices. We demonstrate small-area cells and 40 cm 2 perovskite mini-modules with power conversion efficiencies of up to 19% and 17%, respectively. Furthermore, external radiation efficiency (ERE) measurement carried out to characterize the uniformity of mini-modules and study the perovskite degradation.

Luminescence-based measurement techniques, such as electroluminescence (EL) and photoluminescence (PL), are great methods to evaluate the quality of solar cell materials and their electric contacts. Furthermore, imaging these responses can provide insights into the spatial character of the samples. In this work, we discuss and demonstrate the ability of our unique EL/PL system equipped with light/dark current density-voltage (JV) measurement capabilities built to observe the degradation mechanism of perovskite minimodules and the small area devices. Here, we report the fabrication of this system including the software capabilities and analysis methods. We briefly demonstrate the capabilities by presenting EL images of perovskite minimodules before and after stressing under constant current conditions. By converting the EL image into a histogram plot we provide a pathway for quantitative analysis of the EL images as a function of degradation time. In addition, we demonstrate EL, PL, and JV degradation as a function of time of four small area perovskite devices measured together at an elevated temperature. We show the acquired EL and PL images and how these and the device efficiency change as a function of time. These examples demonstrate the capability of the system and show that by repeating these measurements at multiple temperatures the degradation mechanisms and activation energies can be investigated.

Lewis base molecules that bind undercoordinated lead atoms at interfaces and grain boundaries (GBs) are known to enhance the durability of metal halide perovskite solar cells (PSCs). Using density functional theory calculations, we found that phosphine-containing molecules have the strongest binding energy among members of a library of Lewis base molecules studied herein. Experimentally, we found that the best inverted PSC treated with 1,3-bis(diphenylphosphino)propane (DPPP), a diphosphine Lewis base that passivates, binds, and bridges interfaces and GBs, retained a power conversion efficiency (PCE) slightly higher than its initial PCE of ~23% after continuous operation under simulated AM1.5 illumination at the maximum power point and at ~40°C for >3500 hours. DPPP-treated devices showed a similar increase in PCE after being kept under open-circuit conditions at 85°C for >1500 hours.

Perovskite solar modules (PSMs) have shown remarkable photovoltaic potentials, but they still suffer from large power conversion efficiency (PCE) loss on scale‐up and instability due to inferior uniformity and crystallization over large areas. Herein, the scalable production of efficient and stable PSMs using a suite of all‐scalable fabrication methods featuring a two‐step blade/dip‐coating approach to deposit the perovskite absorber layer is demonstrated. Rubidium chloride is introduced to embed (PbI 2 ) 2 RbCl complex seeds in the first‐deposited PbI 2 precursor, which assists in uniform crystallization of the perovskite layer with high crystallinity and reduced defect density over large areas. Following the optimization of RbCl additives, a champion PSM with 17.9% PCE on a 7.6 × 7.6 cm 2 substrate with a 37 cm 2 aperture area is achieved. Moreover, the RbCl‐incorporated PSMs demonstrate excellent reproducibility and stability under continuous 1 sun illumination. This work shows that the two‐step blade/dip coating is a promising method for producing high‐efficiency and stable PSMs on an industrially relevant scale.

In this work, we fabricate antimony selenosulfide (Sb2(S, Se)3) thin film solar cells by a hydrothermal method followed by a post-deposition annealing process at different temperatures. The effects of the annealing temperature on the morphological and structural properties of the Sb2(S, Se)3 films are systematically investigated by scanning electron microscopy and X-ray diffraction analyses. We find that a proper annealing temperature leads to a high-quality Sb2(S, Se)3 film with large crystal grains, proper stoichiometry, and high crystallinity. After optimizing the process, we obtained Sb2(S, Se)3 solar cells with an improved power conversion efficiency from 2.04 to 8.48%.

Hybrid organic-inorganic metal halide based perovskite films prepared in device relevant structures are examined by mapping spectroscopic ellipsometry measurements to determine spatial variations in structural and complex optical properties of the perovskite film. The measurements are repeated several times over the course of 48 hours in order to track changes in these properties as well as the spatial dependence in how the film degrades. Preliminary analysis of mapping and time dependent measurements of a (FAPbI3)0.95(MAPbBr3)0.05 perovskite film in a device-like structure consisting of soda lime glass superstrate / indium tin oxide top contact / PEDOT:PSS hole transport layer / perovskite film suggests that degradation is indicated by decreases in relative density of the perovskite nucleation layers, changes in perovskite effective film thickness, and reduction in the quality of fit indicated by increases in thee the mean square error (MSE) over time when fixing the complex optical properties of the perovskite to those obtained prior to degradation. The increase in the MSE and reduced quality of fit implies that the initial perovskite optical properties are insufficient to describe changes in the opto-electronic response during degradation occurring simultaneous to changes in the film structure. These changes vary with position from the center of the sample to the corner. This approach develops the methodology in analyzing spatially dependent variations in perovskite materials which will be necessary during scale up for large area depositions and industrial fabrication.

The utilization of solar energy into electrochemical reduction systems has received considerable attention. Most of these attempts have been conducted in a single electrolyte without a membrane. Here, we report the system combined by the electrochemical CO2 reduction on the Au dendrite electrode and the water oxidation on the Co-Pi electrode with a Nafion membrane. An efficient reduction of CO2 to CO in the cathode using the proton from water oxidation in the anode is conducted using perovskite solar cells under 1 sun condition. The sustainable reaction condition is secured by balancing each reaction rate based on products analysis. Through this system, we collect reduction products such as CO and H2 and oxidation product, O2, separately. Employing separation of each electrode system and series-connected perovskite solar cells, we achieve 8% of solar to fuel efficiency with 85% of CO selectivity under 1 sun illumination.

Using the slot-die coating technique, we demonstrate a scalable production process for perovskite solar minimodules (PSMs). To enable uniform coating of perovskite films on FTO glass substrates in an ambient environment, we carried out an investigation on the perovskite precursor solution with a focus on chemistry and processing optimization. Perovskite solar modules (PSMs) prepared by scalable slot-die coating deliver power conversion efficiencies of up to 14% with an active area of 39.2 cm 2 under AM1.5G solar irradiation and ~10% PCE under AM0 spectrum. Current density vs. voltage characterization under AM0 and AM1.5G simulated solar spectra, acquired within an irradiance and temperature control chamber.

Wide‐bandgap perovskite solar cells (WBG PSCs) have gained attention as promising tandem partners for silicon solar cells due to their complementary absorption, superb open‐circuit voltage, and an easy solution process. Recently, both their performance and stability have been improved by compositional engineering or defect passivation strategies, due to the modulation of perovskite crystal size and reduction of crystal defects. Herein, a report on the thermally induced phase control (TIPC) strategy is provided, which enables efficient and photostable WBG PSCs without compositional engineering by exploring a thermal annealing process window (100–175 °C and 3–60 min) of the WBG perovskite films. Within this window, a key annealing regime is found that produces preferred crystal orientations of lead iodide and the WBG perovskite, suppressing phase segregation and reducing charge recombination in the perovskites. The WBG PSCs (composition of FA0.75MA0.15Cs0.1PbI2Br and Eg of 1.73 eV) optimized by TIPC exhibit an excellent power conversion efficiency (PCE) of 18.60% and improved operational stability, maintaining >90% of the maximum PCE (during maximum power point tracking) without encapsulation after 12 h of operation (air mass 1.5 global irradiation in ambient air conditions) or after 500 h of operation (white light‐emitting diode irradiation (100 mW cm−2) in N2 conditions).

A facile and low-temperature process to prepare planar perovskite solar cells (PSCs) has led to considerable progress in flexible solar cells toward high throughput production based on a roll-to-roll process. However, the performance of planar PSCs is still lower than that of mesoscopic PSCs using a high temperature process. Here, we report a new concept of a low temperature processed porous planar electron transport layer (ETL) inspired by a mesoporous structure for improving the performance of flexible devices. The structurally and energetically designed porous planar ETL induced the formation of a high quality perovskite and a preferred band alignment, resulting in improved charge collection efficiency in a fabricated device. Through the porous planar ETL, we achieved a power conversion efficiency (PCE) of 20.7% with a certified efficiency of 19.9% on a flexible substrate, which is the highest PCE reported to date. In addition, for the first time, we succeed in fabricating a large area flexible module with the porous planar ETL, demonstrating a PCE of 15.5%, 12.9% and 11.8% on an aperture area of 100 cm(2), 225 cm(2) and 400 cm(2), respectively. We believe that this strategy will pave a new way for realizing highly efficient flexible PSCs.

For commercializing perovskite solar cells (PSCs), moisture-tolerant materials are required because a moisture-free environment cannot be maintained on an actual production line (large scale). Recently, PSCs with efficiency exceeding 22% have been fabricated using Li-doped mesoporous TiO2 as an electron transport layer (ETL). However, the use of Li can negatively influence device stability during the fabrication process under humid air because of its hydroscopic property. Here, we report a strategy for improving processing stability without sacrificing the power conversion efficiency (PCE) under a humid atmospheric environment by employing a mesoporous BaSnO3 as an ETL. Using the mesoporous BSO ETL, we achieved a certified efficiency of 21.3% and stabilized efficiency of 21.7%. Furthermore, the BSO-based PSCs also exhibited better processing stability than Li-doped TiO2-based PSCs under humid air. We believe that this strategy of introducing BSO into PSCs will accelerate the commercialization of PSCs.

CO2 is a major contributor to global warming and greenhouse effect. To reduce the accumulation of CO2 in the atmosphere, various strategies for CO2 conversion to fuels have been developed. Among the various systems for CO2 conversion, photoelectrochemical and electrochemical CO2 reductions have been attracted as a promising system due to their ambient reaction conditions and high energy efficiency. However, the success in this approach requires further in-depth understanding of catalysis because it involves highly complex multi-step reactions. Here, various rational design principles of cathode catalysts for an efficient CO2 reduction to useful fuels were suggested. As a photocathode material for photoelectrochemical system, p-type semiconductors (i.e. p-CdTe, layered p-CuO/Cu2O thin film, and p-ZnTe) were developed and their performances are improved by various strategies: i) using a homogeneous catalyst (i.e. pyridine) with photocathode and ii) decoration of photocathode surface with electrocatalysts such as various transition metals (i.e. Ag, Au, Cd, Cu, Pb, and Sn) and conducting polymer, polypyrrole (Fig.1). These modifications effectively enhanced CO2 conversion to fuels in terms of Faradaic efficiency, reaction selectivity, and production rates. It is worth noting that CO2 was photoelectrochemically reduced to useful products (e.g. formic acid, carbon monoxide and methanol) without any significant overpotential loss under visible light irradiation on the prepared photocathodes. In electrochemical CO2 conversion, the various metal candidates, transition metals attracted many attention due to its low-cost, low-toxicity, and high-selectivity for CO2 conversion. Because general electrochemical catalysis is highly correlated with mass diffusion, crystal orientation, surface area, and conductivity, manipulating the architecture of electrode is an effective method for improving catalytic performance. Here we developed hierarchical 3D Cu pillar, Sn dendrite, and hexagonal Zn electrodes as electrocatalysts by facile electrodeposition methods (Fig. 2). Cu pillar, Sn dendrite and hexagonal Zn electrodes achieved significantly enhanced CO2 reduction performances in terms of current density and Faradaic efficiency compared to their pristine metal foils. Furthermore, experimental and theoretical studies additionally elucidated the origin of the catalytic behaviors of the prepared electrodes.[1]

Electrocatalytic CO 2 conversion into fuel is a prospective strategy for the sustainable energy production. However, still many parts of the catalyst such as low catalytic activity, selectivity, and stability are challenging. Herein, a hierarchical hexagonal Zn catalyst showed highly efficient and, more importantly, stable performance as an electrocatalyst for selectively producing CO. Moreover, we found that its high selectivity for CO is attributed to morphology. In electrochemical analysis, Zn (101) facet is favorable to CO formation whereas Zn (002) facet favors the H 2 evolution during CO 2 electrolysis. Indeed, DFT calculations showed that (101) facet lowers a reduction potential for CO 2 to CO by more effectively stabilizing a . COOH intermediate than (002) facet. This further suggests that tuning the crystal structure to control (101)/(002) facet ratio of Zn can be considered as a key design principle to achieve a desirable product from Zn catalyst.

To achieve high performance of electrochemical CO2 reduction, a series of Cu pillar electrodes (Cu-2.5 h, Cu-5 h) were fabricated by using an electrodeposition method, and then their catalytic activities and reaction mechanisms were investigated. The series of Cu pillar electrodes exhibited improved electrocatalytic activities toward CO2 reduction to formic acid (HCOOH) as Cu pillars on electrodes developed. The Cu-5 h electrode performed well with a 28% Faradaic efficiency for formic acid at -0.5 V (vs. RHE). X-ray diffraction (XRD) analysis indicated that the enhanced catalytic activities were primarily attributable to the increased (111) facet, which is energetically favourable for the production of HCOOH. Also, ultraviolet photoelectron spectroscopy (UPS) and in situ electrochemical impedance spectroscopy (EIS) results suggested that the series of Cu pillar structure electrodes improved the electron transfer to adsorbed CO2 due to the decreased work function of the Cu pillar structure.

Catalysis is a key technology for the synthesis of renewable fuels through electrochemical reduction of CO2 . However, successful CO2 reduction still suffers from the lack of affordable catalyst design and understanding the factors governing catalysis. Herein, we demonstrate that the CO2 conversion selectivity on Sn (or SnOx /Sn) electrodes is correlated to the native oxygen content at the subsurface. Electrochemical analyses show that the reduced Sn electrode with abundant oxygen species effectively stabilizes a CO2 (.-) intermediate rather than the clean Sn surface, and consequently results in enhanced formate production in the CO2 reduction. Based on this design strategy, a hierarchical Sn dendrite electrode with high oxygen content, consisting of a multi-branched conifer-like structure with an enlarged surface area, was synthesized. The electrode exhibits a superior formate production rate (228.6 μmol h(-1)  cm(-2) ) at -1.36 VRHE without any considerable catalytic degradation over 18 h of operation.