Large-area Perovskite Solar Cells Research Articles

Surface Property Regulation of a Magnetron-Sputtered NiOx Hole Transport Layer for High-Performance Inverted Perovskite Solar Cells.

The inverted perovskite solar cells (PSCs) are gaining increasing attention recently for their unprecedented advantages, such as better integration with tandem and flexible designs, negligible hysteresis, good operational stability, and compatibility with commercially scalable fabrication approaches. Nickel oxide (NiOx) films prepared by magnetron sputtering technology exhibit excellent scalability and reproducibility, which could well meet the requirements of the large-scale production of inverted PSCs. However, NiOx prepared by vacuum methods generally has fewer surface hydroxyl groups, deteriorating the wettability and damaging the interface contact with the perovskite. Particularly, the Ni3+ defects on the NiOx surface could lead to unfavorable redox reactions with organic cations in the perovskite under high temperatures, promoting the rapid degradation of the perovskite. Thus, surface regulation of sputtered NiOx is imperative for high-performance PSCs. Herein, 4-(trifluoromethyl) phenylcarbamate hydrochloride (TFFA) was used to regulate the surface properties of sputtered NiOx. The strongly electronegative F ions in TFFA passivated the Ni3+ defects on the NiOx surface, suppressed unfavorable interface reactions, and improved charge recombination. The polar ammonium functional group was used to adjust the surface energy of NiOx, thereby improving the wettability and optimizing the crystallization kinetics of the perovskite. As a result, the power conversion efficiency (PCE) of PSCs reached 22.76%, which was among the highest PCEs reported for sputtered NiOx-based inverted PSCs to date. Moreover, the unencapsulated target devices exhibited better stability, maintaining over 85% of the initial PCE after aging for approximately 1200 h in a N2 environment. Our achievements pointed out a practical strategy for enhancing the performance of sputtered NiOx-based inverted PSCs, which could potentially accelerate the development and application of large-area PSCs.

Exploring the efficiency enhancement of perovskite solar cells by chemical bath depositing SnO2 on mesoporous TiO2 electrode

This study presents a groundbreaking approach to enhance the efficiency of perovskite solar cells (PSCs) by employing Chemical Bath Deposited (CBD) SnO2 on mesoporous TiO2 (m-TiO2) as an electron transport layer (ETL) without a traditional compact TiO2 (c-TiO2) layer between FTO (fluorine-doped tin oxide) and m-TiO2 ETL. Our investigation reveals that this method significantly improves carrier dynamics, as evidenced by reduced time constants compared to traditional ETLs. The CBD SnO2 not only augments electron transport but also effectively reduces defect density in m-TiO2 films. These enhancements are reflected in the improved photovoltaic parameters of the cells, including higher open-circuit voltage (VOC), short-circuit current (JSC), fill factor (FF), and an impressive power conversion efficiency (PCE) exceeding 23.62 %. The study further underscores the scalability of this technology, highlighting advancements in screen printing and chemical bath deposition techniques vital for large-area PSC applications. Remarkably, the uniformity of PCE across large-area cells confirms the efficacy and consistency of this approach, which provides a new and general strategy for preparing high-efficiency PSCs.

Large-Area Perovskite Solar Modules Based on Uniformity Engineering of Perovskite Films: The Critical Role of Methyldiphenylphosphine Oxide Additive.

Perovskite solar cells (PSCs) have led to distinguished achievements and become one of the state-of-the-art photovoltaic technologies. Undoubtedly, reliable preparation of large area high-quality perovskite (PVK) films with uniform optoelectronic properties has become a critical and challenging task to transition PSCs from lab to market. Here, methyldiphenylphosphine oxide (MDPPO) is employed as an additive in a PVK precursor solution to promote uniform conductivity and carrier transport of PVK films. More important, to check its compatibility with the upscaling process, the MDPPO additive strategy was further applied to doctor-blade large-area PVK films. As a result, benefit from the favorable role of MDPPO additive, the power conversion efficiencies (PCEs) of small-area PSCs reach 23.85% with superb open circuit voltage (Voc) of 1.15 V and fill factor of 81.21%, while an impressive PCE of 19.22% was achieved for the large-area PSC minimodules with active area of 61.48 cm2. Remarkably, the MDPPO modified device exhibits significantly improved operational stability, maintaining an initial efficiency of 68% even after 750 h under continuous 1-sun illumination. Our achievements will provide profound insight and further guidance for the scale-up process of PSCs from lab to large-scale modules.

Advancements in Scaling Up Perovskite Solar Cells: From Small-Area Devices to Large-Scale Modules.

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) has exceeded those of conventional thin-film solar cell technologies, and the speed at which this increase has been achieved is unprecedented in the history of photovoltaics. Despite the significant progress achieved by PSCs at the laboratory level, their commercial prospects still face two significant challenges: scaling up in size and ensuring long-term stability. Small-area devices (~1 cm2) are typically fabricated using spin-coating. However, this approach may not be suitable for preparing the large-area (>100 cm2) substrates required for commercialization. Thus, new materials and methods must be developed to facilitate the coating of large-area PSCs. This review will discuss the development of scaling up organic-inorganic hybrid PSCs and the challenges of increasing the device area. Furthermore, it will provide an overview of the methodologies for achieving high-efficiency perovskite solar modules.

Gas Molecule Assisted All-Inorganic Dual-Interface Passivation Strategy for High-Performance Perovskite Solar Cells.

The trap states at both the upper and bottom interfaces of perovskite layers significantly impact non-radiative carrier recombination. The widely used solvent-based passivation methods result in the disordered distribution of surface components, posing challenges for the commercial application of large-area perovskite solar cells (PSCs). To address this issue, a novel NH3 gas-assisted all-inorganic dual-interfaces passivation strategy is proposed. Through the gas treatment of the perovskite surface, NH3 molecules significantly enhanced the iodine vacancy formation energy (1.54eV) and bonded with uncoordinated Pb2+ to achieve non-destructive passivation. Meanwhile, the reduction of the film defect states is accompanied by a decrease in the work function, which promotes carrier transport between the interface. Further, a stable passivation layer is constructed to manage the bottom interfacial defects using inorganic potassium tripolyphosphate (PT), whose ─P═O group effectively mitigated the charged defects and lowered the carrier transport barriers and nucleation barriers of PVK, while the gradient distribution of K+ improved the crystalline quality of PVK film. Based on the dual-interface synergistic effect, the optimal MA-contained PSCs with an effective area of 0.1 cm2 achieved an efficiency of 24.51% and can maintain 90% of the initial value after aging (10-20% RH and 20°C) for 2000h.

High-Throughput Roll-to-Roll Processed Large-Area Perovskite Solar Cells Using Rapid Radiation Annealing Technique.

The development of a stable roll-to-roll (R2R) process for flexible large-area perovskite solar cells (PSCs) and modules is a pressing challenge. In this study, we introduced a new R2R PSC manufacturing system that employs a two-step deposition method for coating perovskite and uses intensive pulsed light (IPL) for annealing. This system has successfully fabricated small-sized cells and the first-ever large-sized, R2R-processed flexible modules. A key focus of our work was to accelerate the conversion of PbI2 to perovskite. To this end, we utilized IPL annealing and incorporated additives into the PbI2 layer. With these modifications, the R2R-processed perovskite films achieved a power conversion efficiency (PCE) of 16.87%, representing the highest reported value for R2R two-step processed PSCs. However, these cells exhibited hysteresis in reverse and forward PCE measurements. To address this, we introduced a dual-annealing process consisting of IPL followed by a 2-min thermal heating step. This approach successfully reduced hysteresis, resulting in low-hysteresis, R2R-processed flexible PSCs. Moreover, we fabricated large-scale flexible modules (10 × 10 cm2) with a PCE of 11.25% using the dual-annealing system, marking a significant milestone in this field.

Defect Passivation and Fabrication of Stable Large-Area (2.0 cm2) Perovskite Solar Cells with Cost-Effective Metal Contacts

Defect Passivation and Fabrication of Stable Large-Area (2.0 cm²) Perovskite Solar Cells with Cost-Effective Metal Contacts

Room Temperature Ionic Liquid Capping Layer for High Efficiency FAPbI3 Perovskite Solar Cells with Long-Term Stability.

Ionic liquid salts (ILs) are generally recognized as additives in perovskite precursor solutions to enhance the efficiency and stability of solar cells. However, the success of ILs incorporation as additives is highly dependent on the precursor formulation and perovskite crystallization process, posing challenges for industrial-scale implementation. In this study, a room-temperature spin-coated IL, n-butylamine acetate (BAAc), is identified as an ideal passivation agent for formamidinium lead iodide (FAPbI3) films. Compared with other passivation methods, the room-temperature BAAc capping layer (BAAc RT) demonstrates more uniform and thorough passivation of surface defects inthe FAPbI3 perovskite. Additionally, it provides better energy level alignment for hole extraction. As a result, the champion n-i-p perovskite solar cell with a BAAc capping layer exhibits a power conversion efficiency (PCE) of 24.76%, with an open-circuit voltage (Voc) of 1.19V, and a Voc loss of ≈330mV. The PCE of the perovskite mini-module with BAAc RT reaches 20.47%, showcasing the effectiveness and viability of this method for manufacturing large-area perovskite solar cells. Moreover, the BAAc passivation layer also improves the long-term stability of unencapsulated FAPbI3 perovskite solar cells, enabling a T80 lifetime of 3500h when stored at 35% relative humidity at room temperature in an air atmosphere.

Dopant-additive synergism enhances perovskite solar modules

Perovskite solar cells (PSCs) are among the most promising photovoltaic technologies owing to their exceptional optoelectronic properties1,2. However, the lower efficiency, poor stability and reproducibility issues of large-area PSCs compared with laboratory-scale PSCs are notable drawbacks that hinder their commercialization3. Here we report a synergistic dopant-additive combination strategy using methylammonium chloride (MACl) as the dopant and a Lewis-basic ionic-liquid additive, 1,3-bis(cyanomethyl)imidazolium chloride ([Bcmim]Cl). This strategy effectively inhibits the degradation of the perovskite precursor solution (PPS), suppresses the aggregation of MACl and results in phase-homogeneous and stable perovskite films with high crystallinity and fewer defects. This approach enabled the fabrication of perovskite solar modules (PSMs) that achieved a certified efficiency of 23.30% and ultimately stabilized at 22.97% over a 27.22-cm2 aperture area, marking the highest certified PSM performance. Furthermore, the PSMs showed long-term operational stability, maintaining 94.66% of the initial efficiency after 1,000 h under continuous one-sun illumination at room temperature. The interaction between [Bcmim]Cl and MACl was extensively studied to unravel the mechanism leading to an enhancement of device properties. Our approach holds substantial promise for bridging the benchtop-to-rooftop gap and advancing the production and commercialization of large-area perovskite photovoltaics.

Scalable large area perovskite solar cell modules fabricated with high humidity tolerance by vacuum deposition

Vacuum deposition is promising for large-area, high-throughput production of perovskite solar cells (PSCs). However, the strict low humidity control increases the costs for manufacturing facilities and hinders the large-scale production of PSCs. In this work, a sequential deposition method was used to prepare the perovskite intermediate phase, and the impact of ambient humidity was studied during the annealing process. It is shown that proper humidity has a positive effect on the perovskite layer, which is conducive to accelerate the reaction between organic salts and PbI2 and improve the surface morphology of the film. The perovskite annealing under 55 % relative humidity exhibits fewer defects and faster carrier transport kinetics. The resulting PSCs, with all layers fabricated adopting vapor deposition, yield a power conversion efficiency (PCE) of 15.01 % for the large area modules of 100 cm2 (active area 64.8 cm2). More impressively, the PCE of the unpackaged cell modules remained above 80 % after being placed in ambient air for 1200 h. The results open a promising way for scalable fabrication of humidity-tolerant large-area perovskite solar cell modules and shed light on the industrial production of PSCs.

Preparation of high-performance large-area perovskite solar cells by atomic layer deposition of metal oxide buffer layer

Perovskite solar cells have been widely recognized as the most promising new-type photovoltaic device due to its power conversion efficiency rapidly increasing from 3.8% to over 26% in merely fifteen years. However, the high performances are achieved mainly on small area cells with an active area lower than 0.1 cm<sup>2</sup>. When enlarging the active area of perovskite solar cells, the efficiency falls dramatically. So, how to reduce the gap between performances of small area cells and large area cells gradually becomes a critical point in the path towards the commercialization of perovskite photovoltaic technology. Herein, a strategy of pre-growing thin layer of TiO<sub>2</sub> on a rough FTO substrate by atomic layer deposition method before spin-coating SnO<sub>2</sub> nanoparticles is proposed. Due to the inherent conformal film growth mode of atomic layer deposition, the FTO substrate can be completely covered by TiO<sub>2</sub>, thus preventing the direct contact between local protrusions of FTO and perovskite layer and impeding the current leakage phenomenon, which can be verified by the measurements from X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy, and further proved by the dark current measurement. By using this method, the repeatability and consistency of the small area cell fabrication technology on the same substrate are improved obviously. The improved electron transport process revealed by photoluminescence results and incident light management process revealed by external quantum efficiency results also brings about better solar cell performances. More importantly, highly efficient 0.5 cm<sup>2</sup> large area perovskite solar cells are fabricated through optimization of TiO<sub>2</sub> thickness. When growing 200 cycles TiO<sub>2</sub> (~9 nm in thickness) by using atomic layer deposition technology, the champion large area perovskite solar cell possesses a power conversion efficiency as high as 24.8% (certified 24.65%). The device performances also show excellent repeatability between different fabrication batches. The perovskite solar cell with TiO<sub>2</sub> buffer layer grown by the atomic layer deposition method can still retain over 95% of its initial efficiency after having been stored in a nitrogen atmosphere for 1500 h. The technique proposed in this paper can be helpful in manufacturing perovskite solar cell modules in the realistic photovoltaic market and can be extended to the large area fabrication of other perovskite optoelectronic devices such as light emitting diode, laser and detector.

Towards scalability: progress in metal oxide charge transport layers for large-area perovskite solar cells

In this review article, we aim to offer a focused overview of metal oxide CTLs for large-area PSCs, emphasizing recent advancements in deposition techniques, modification strategies, and their suitability for large-area device applications.

Eco-Friendly Solvent Engineered CsPbI2.77 Br0.23 Ink for Large-Area and Scalable High Performance Perovskite Solar Cells.

The performance of large-area perovskite solar cells (PSCs) has been assessed for typical compositions, such as methylammonium lead iodide (MAPbI3 ), using a blade coater, slot-die coater, solution shearing, ink-jet printing, and thermal evaporation. However, the fabrication of large-area all-inorganic perovskite films is not well developed. This study develops, for the first time, an eco-friendly solvent engineered all-inorganic perovskite ink of dimethyl sulfoxide (DMSO) as a main solvent with the addition of acetonitrile (ACN), 2-methoxyethanol (2-ME), or a mixture of ACN and 2-ME to fabricate large-area CsPbI2.77 Br0.23 films with slot-die coater at low temperatures (40-50 °C). The perovskite phase, morphology, defect density, and optoelectrical properties of prepared with different solvent ratios are thoroughly examined and they are correlated with their respective colloidal size distribution and solar cell performance. The optimized slot-die-coated CsPbI2.77 Br0.23 perovskite film, which is prepared from the eco-friendly binary solvents dimethyl sulfoxide:acetonitrile(0.8:0.2 v/v), demonstrates an impressive power conversion efficiency (PCE) of 19.05%. Moreover, the device maintains ≈91% of its original PCE after 1 month at 20% relative humidity in the dark. It is believed that this study will accelerate the reliable manufacturing of perovskite devices.

Engineering of antisolvent dripping for large-area perovskite solar cell fabrication under air ambient conditions

Engineering of antisolvent dripping for large-area perovskite solar cell fabrication under air ambient conditions

Buried-Metal-Grid Electrodes for Efficient Parallel-Connected Perovskite Solar Cells.

The limited conductivity of existing transparent conducting oxide (TCO) greatly restricts the further performance improvement of perovskite solar cells (PSCs), especially for large-area devices. Herein, buried-metal-grid tin-doped indium oxide (BMG ITO) electrodes are developed to minimize the power loss caused by the undesirable high sheet resistance of TCOs. By burying 140-nm-thick metal grids into ITO using a photolithography technique, the sheet resistance of ITO is reduced from 15.0 to 2.7 Ω sq-1 . The metal step of BMG over ITO has a huge impact on the charge carrier transport in PSCs. The PSCs using BMG ITO with a low metal step deliver power conversion efficiencies (PCEs) significantly better than that of their counterparts with higher metal steps. Moreover, compared with the pristine ITO-based PSCs, the BMG ITO-based PSCs show a smaller PCE decrease when scaling up the active area of devices. The parallel-connected large-area PSCs with an active area of 102.8 mm2 reach a PCE of 22.5%. The BMG ITO electrodes are also compatible with the fabrication of inverted-structure PSCs and organic solar cells. The work demonstrates the great efficacy of improving the conductivity of TCO by BMG and opens up a promising avenue for constructing highly efficient large-area PSCs.

PTAA/Ag-Based Large Area Perovskite Solar Cells Toward Low-Cost and Ambient Stability

PTAA/Ag-Based Large Area Perovskite Solar Cells Toward Low-Cost and Ambient Stability

Efficient MAPbI3-based perovskite solar cells exceeding 21% efficiency via aging treatment

Recently, the demand for large-area and high-efficiency perovskite solar cells (PSCs) has increased, and a two-step process for high-efficiency large-area PSCs is actively being studied. However, the two-step process is still less efficient than the one-step antisolvent dripping process owing to the poor interdiffusion of organic components. In this study, a perovskite layer using a hybrid deposition method in which an excess of methylammonium iodide (MAI) solution is reacted with thermally evaporated PbI2 is reported. The perovskite film quality is improved by reacting unreacted residual PbI2 with excess MAI by applying daily electrical stress and aging for 60 days in a glovebox. The best PSC exhibits a PCE of 21.1 %, the highest reported power conversion efficiency among PSCs based on the two-step hybrid deposited MAPbI3 perovskite, with a large enhanced open-circuit voltage of 1.21 V and fill factor of 80.8 %. Moreover, using the solvent pre-heat treatment method, the reaction of unreacted PbI2 with MAI is accelerated, and the aging time of PSCs is shortened from 60 to 7 days, showing a PCE value of 20.7 %. Furthermore, we present a large-area PSC with a PCE of 19.4 %, indicating that the PCE can be improved through the hybrid deposition method.

Refining interface compatibility and carrier management via π-π conjugated stacking for efficient and stable perovskite solar cells based on low-temperature processing

ABSTRACT Deficiencies and instability in the ETL, perovskite layer, or their interface contribute to carrier nonradiative recombination losses. To address these issues, we propose an electron collection and injection optimisation strategy that focuses on enhancing the compatibility and charge transfer performance at the ETL-perovskite interface. Our approach involves low-temperature modification TiO2 with pyrimidine-2-carboximidamide acetate (PCA) through π-π stacking, reducing the surface energy and improving the interfacial compatibility. At the same time, a stable organic–inorganic hybrid layer is formed with lead iodide (PbI2) below the perovskite layer. Additionally, we demonstrate long-term ambient stability, with the PSCs retaining approximately 90% of their initial PCE after 100 days. We also fabricate large-area modules, achieving an efficiency of 19.53% with an active area of 36.41 cm2. Highlights The introduction of the π-π stacking multifunctional molecule PCA through a low-temperature process to modify TiO2 film enhances the stability and performance of perovskite solar cells. This novel approach improves interfacial compatibility and reduces defects at the interface, enabling vertically aligned crystal growth of perovskite and increasing the interfacial contact area. By effectively removing two types of Hydroxyl groups over the low-temperature TiO2 film through multiple surface chemical reactions, the strategy mitigates nonradiative recombination, leading to reduced energy losses and improved performance in both small and large-area perovskite solar cell modules.

Cross-linked polyelectrolyte reinforced SnO2 electron transport layer for robust flexible perovskite solar cells

SnO2 electron transport layer (ETL) is a vital component in perovskite solar cells (PSCs), due to its excellent photoelectric properties and facile fabrication process. In this study, we synthesized a water-soluble and adhesive polyelectrolyte with ethanolamine (EA) and poly-acrylic acid (PAA). The linear PAA was crosslinked by EA, forming a 3D network that stabilized the SnO2 nanoparticle dispersion. An organic–inorganic hybrid ETL is developed by introducing the cross-linked PAA-EA into SnO2 ETL, which prevents nano particle agglomeration and facilitates uniform SnO2 film formation with fewer defects. Additionally, the PAA-EA-modified SnO2 facilitated a uniform and compact perovskite film, enhancing the interface contact and carrier transport. Consequently, the PAA-EA-modified PSCs exhibited excellent PCE of 24.34% and 22.88% with high reproducibility for areas of 0.045 and 1.00 cm2, respectively. Notably, owing to structure reinforce effect of PAA-EA in SnO2 ETL, flexible device demonstrated an impressive PCE of 23.34% while maintaining 90.1% of the initial PCE after 10,000 bending cycles with a bending radius of 5 mm. This successful approach of polyelectrolyte reinforced hybrid organic–inorganic ETL displays great potential for flexible, large-area PSCs application.

Valine-Modified PbI2 for the Growth of Pinhole-Free Lead Halide Perovskite Thin Films by Vapor–Solid Reaction

In recent years, the efficiency of perovskite solar cells (PSCs) has rapidly increased, making PSCs commercially viable and able to compete with silicon solar cells. However, the technology for large-scale production of perovskite thin films still poses a significant challenge to the commercialization of PSCs. This is mainly because the thickness of the perovskite light-absorbing film is less than 1 μm and easily produces pinholes during large-scale production, causing serious charge recombination and reducing the efficiency of the device. As a result, the efficiencies of most large-scale PSC modules are significantly lower than those of small-size devices. Vapor-reaction technology is considered a crucial method to enhance the uniformity of perovskite thin films. However, current techniques are not yet advanced enough to deposit pinhole-free perovskite thin films on a large scale. One major challenge is that lead iodide (PbI2) precursor thin films have a tendency to develop a sheet-like structure with a loose morphology, which contributes to the formation of pinholes in the perovskite film. Additionally, uncoordinated Pb2+ could be easily generated in the PbI2 film during thermal evaporation, causing an increase in trap-states in the perovskite crystal. To address this, we developed a valine treatment process in this study to change the preferred orientation of PbI2 from a sheet-like to a particle-like aggregate and obtained compact PbI2 thin films. Meanwhile, this valine vapor treatment can significantly reduce the uncoordinated Pb2+ in PbI2 films. Based on this, we successfully prepared pinhole-free perovskite thin films using a vapor–solid reaction. Perovskite films based on these valine-treated PbI2 exhibited a reduced trap density and significantly improved PSCs’ performance, with a maximum efficiency exceeding 21%. Large-area PSC mini-modules (5 cm × 5 cm) produced from the perovskite film (30 cm × 30 cm) showed uniformly distributed power conversion efficiency values exceeding 17%, with the highest value reaching 18.78%. We believe that this facile valine vapor treatment holds great potential for the large-scale production of stable and high-efficiency PSC modules.