Stability Of Perovskite Devices Research Articles

Multi‐Point Collaborative Passivation of Surface Defects for Efficient and Stable Perovskite Solar Cells

AbstractThe inherent defects (lead iodide inversion and iodine vacancy) in perovskites cause non‐radiative recombination and there is also ion migration, decreasing the efficiency and stability of perovskite devices. Eliminating these inherent defects is critical for achieving high‐efficiency perovskite solar cells. Herein, an organic molecule with multiple active sites (4,7‐bromo‐5,6‐fluoro‐2,1,3‐phenylpropyl thiadiazole, M4) is introduced to modify the upper interface of perovskites. When M4 interacts with the perovskite surface, the active bromine (Br) site interacts with lead (Pb) at the surface to repair iodine atomic vacancy defects. The fluorine (F) site of M4 interacts with Pb to correct octahedral crystal lattice distortions and eliminate PbI defects. Additionally, sulfur–iodine (S–I) interactions reduce I–I dimerization and eliminate IPb defects. It is also calculated that the energy level of M4 aligns with the band gap, promoting charge transfer. As a result, the perovskite devices achieve an efficiency of 25.1%, a stabilized power output (SPO) of 25.0%, a voltage of 1.19 V, and a fill factor of 85.2%. The device retains 95% of its initial efficiency after 2000 h of ageing in a nitrogen atmosphere. Thus, multi‐point cooperative passivation of surface defects provides an effective method to improve the efficiency and stability of perovskite solar cells.

Suppressing interfacial nonradiative recombination by alkali hydroxides for efficient blue perovskite light-emitting diodes

Blue perovskite light-emitting diodes (PeLEDs) provide unlimited possibility in the field of optoelectronic devices due to their excellent characteristics. However, the widely used hole-transport material, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), has strong acidity and poor conductivity which deteriorate the efficiency and stability of perovskite devices. In this work, we modified PEDOT:PSS layer using alkalis, LiOH, NaOH, and KOH, to address these issues. Our findings indicated that the indium defect from indium tin oxide substrate was passivated after the introduction of LiOH, which resulted in the suppression of nonradiative recombination. In addition, the conductivity was improved owing to the increased phase separation of PEDOT:PSS. Taking advantage of optimized interface, the small-n phases of quasi-two-dimensional (quasi-2D) perovskite films were redistributed in quantities and dimensions. As results of these improvements, blue PeLEDs possessed the external quantum efficiencies of 5.95 % and an extended half-lifetime with emission-light wavelength of 473 nm. These findings offer an effective strategy to achieve highly efficient blue light-emitting diode.

Strain Regulation and Photophysical Properties in Halide Perovskite

Perovskite solar cells (PSCs) are regarded as the most promising new generation of green energy technology due to their outstanding device performance and simple processing technology. The strain in the active layer of PSCs is primarily caused by lower interionic and intercrystal forces, leading to an increase in defect density and high recombination of carriers, which can negatively impact the performance and stability of perovskite devices. Herein, the origins of strain in perovskite film of solution processing are revealed by conducting strain tests and characterizing photophysical processes. The impacts of strain on optical and electrical properties are summarized, including its effects on molecular interaction force, band structure, defect formation energy, activation energy of ion migration, phase segregation, and phase transition. To mitigate these negative effects, the review introduces several methods for modulating strain in perovskite films, including crystallization, component tailoring, adding additives, and modifying contact layers, which are aimed at improving carrier transport and collection efficiency. It is believed that these approaches will provide scientists with new ways of thinking and system schemes for improving the performance and stability of perovskite solar cells.

Enhanced performance of inverted hybrid perovskite solar cells with interfacial passivation filler

Defects at the interface between the perovskite and charge transport layers in perovskite solar cells serve as sites for non-radiative charge recombination as they are the main energy loss channels that reduce the open-circuit voltage. In this study, we used a small molecule, N-methyl-4-piperidone (NMPD), as an interfacial passivation filler between the perovskite and electron transport layers in inverted organic–inorganic hybrid CH3NH3PbI3 perovskite solar cells. The filler deactivates the charge traps at the interface, which are responsible for non-radiative charge recombination, and improves the electron extraction efficiency. Consequently, it enhanced the power conversion efficiency (PCE) from 16.3% to 20.1% by increasing both the open-circuit voltage and short-circuit current. Furthermore, after 800 h of aging without encapsulation at 35% humidity and 25 °C temperature, the device with NMPD filler retained 78.4% of the initial PCE. This indicates that the interfacial modification filler, with a single carbonyl group, can effectively improve the efficiency as well as the stability of perovskite devices.

Anti-corrosion strategy to improve the stability of perovskite solar cells.

In recent years, perovskite solar cells (PSCs) have been considered as one of the most promising photovoltaic technologies due to their solution processing, cost effectiveness, and excellent performance. The highest certified power conversion efficiency (PCE) achieved to date is 25.8%, which is approaching the best PCE of 26.81% achieved for silicon-based cells. However, perovskite materials are susceptible to various aging stressors, such as humidity, oxygen, temperature, and electrical bias, which hinder the industrialization of perovskite photovoltaic technologies. In this review, we discuss the lifetime of PSCs from the perspective of corrosion science. On one hand, benefiting from a series of anti-corrosion strategies (passivation, surface coating, machining etc.) used in corrosion science, the stability of perovskite devices is remarkably enhanced; on the other hand, given that perovskites are soft crystal lattices, which are different from traditional metals, the revealed degradation processes and specific methods to improve device operation stability can be applied to the field of corrosion, which can enrich and expand corrosion science.

Improved p-i-n MAPbI3 perovskite solar cells via the interface defect density suppression by PEABr passivation.

Organic-inorganic hybrid perovskite solar cells (PSCs) are promising candidates for next-generation photovoltaics due to their excellent optoelectronic properties and process compatibility. In this report, numerical simulations show the effect of perovskite surface defect density on the inverted MAPbI3 perovskite device. The Phenethylammonium bromide (PEABr) is introduced to passivate the MAPbI3 layer surface of the perovskite solar cell devices, PEA+ diffuses into the grain boundaries of the 3D perovskite to form 2D/3D hybrid structure during the thermal annealing process, thus improve the surface morphology and decrease the interface defects between MAPbI3 layer and PCBM layer. The power conversion efficiency (PCE) of the PSCs increased from 17.95% to 19.24% after PEABr treatment. In addition, the 2D/3D hybrid structure can also hinder the intrusion of water and oxygen, the stability of perovskite devices has been greatly improved.

Facet Engineering for Stable, Efficient Perovskite Solar Cells

Facet engineering is an important strategy for tuning the physical, chemical, and electronic properties of a crystal surface, and it also provides an effective route to improve the device performance in many fields. Complex crystal structures with rough morphologies have been observed for most of the hybrid perovskite thin films. Thus, it is speculated whether high-quality crystals with tunable facets can be formed on a perovskite thin film and how the facet properties can influence the device performance. More importantly, the high-quality crystals and tunable facets are also effective strategies to further improve the efficiency and stability of perovskite devices. This perspective provides the challenges to achieving high-quality crystals with tunable facets and discusses the crystal shape, facet properties, and several prospects of facet engineering on perovskite thin films.

Efficient mixed-cation perovskite photovoltaic cells via additive-assisted slot-die deposition

The main objective of this study was to enhance the quality of slot-die-processed perovskite film layer using an additive process that could improve the performance and stability of perovskite devices. To improve slot-die-processed perovskite, 2-hydroxyethyl acrylate (HEA) additive with -OH was utilized as an effective functional group. The addition of HEA controlled the perovskite's growth, enlarged perovskite's grain size, and reduced perovskite's defects. As a result, the slot-die-processed device fabricated with HEA as additive produced a high efficiency of 16.08% and a good stability, maintaining an initial efficiency of 80% under air for 95 days.

Fabrication Strategies and Optoelectronic Applications of Perovskite Heterostructures

AbstractMetal halide perovskites (MHPs) are emerging low‐cost and multifunctional semiconductor materials. They have been widely used in optoelectronic devices such as perovskite solar cells, light‐emitting diodes, photodetectors, memristors, and lasers. Developing new MHPs, defects passivation, optimizing device structures, and packaging techniques are all effective methods to improve photoelectric performance and stability of perovskite devices. Particularly, the fabrication of perovskite/perovskite heterostructures (PPHSs) is a novel and arresting method to obtain stable and high‐performing optoelectronic perovskite devices since it can passivate defects, regulate energy gaps, and provide new carrier transmission modes of MHPs for multiple semiconductor applications. In this paper, representative fabrication strategies of PPHSs including films and single‐crystal heterostructures are reviewed, and their applications in optoelectronic devices are summarized. Furthermore, the challenges and prospects of PPHSs are discussed based on the current status.

Water Stable Haloplumbate Modulation for Efficient and Stable Hybrid Perovskite Photovoltaics

AbstractThe commercialization of perovskite solar cells is mainly limited by their operational stability. Interlayer modification by thin interface materials between the perovskite and the charge transport layers is one of the most effective methods to promote the efficiency and stability of perovskite devices. However, the commonly used interlayer materials do not fulfill all the demands, including good film quality, excellent stability, and passivation capability without interfering with the charge transport. In this work, a water stable haloplumbate [TBA]PbI3 for interfacial modification that meets these demands is proposed, which is formed on the perovskite surface in situ by tetra‐butylammonium iodide treatment. Benefiting from its passivation effect and robustness, the modified devices result in a power conversion efficiency of 22.90% with enhanced environmental and operational stability. In addition, the self‐limiting effect of the reaction contributes to the controllability of device fabrication and the repeatability of device performance.

Role and Contribution of Polymeric Additives in Perovskite Solar Cells: Crystal Growth Templates and Grain Boundary Passivators

Polymers or polymeric materials are used as additives for promoting the nucleation and crystallization of perovskite films to increase the crystal grain size. Due to their high molecular weight, polymers remain within perovskite‐crystal grain boundaries (GBs), where they passivate trap sites. Furthermore, some polymers function as charge‐transport materials in interfacial layers to effectively separate charge carriers and reduce charge recombination. Certain hydrophobic polymers protect perovskite films against moisture, whereas elastic polymers contribute to the mechanical resilience of perovskite films by crosslinking and self‐healing. Although polymeric additives have become essential to perovskite fabrication, a thorough review has not summarized their application to perovskite solar cells. Therefore, various strategies are comprehensively discussed for incorporating typical polymers and 1D polymeric materials into perovskite materials to improve the efficiency and stability of perovskite devices. Herein, thermoplastic, hydrophilic, and conductive polymers and elastomers are focused and related works are chronologically discussed to clearly elucidate the advances in perovskite devices.

The surface of halide perovskites from nano to bulk

The surface of a semiconductor often has a key role in determining its properties. For metal halide perovskites, understanding the surface features and their impact on the materials and devices is becoming increasingly important. At length scales down to the nanoscale regime, surface features become dominant in regulating the properties of perovskite materials, owing to the high surface-to-volume ratio. For perovskite bulk films in the micrometre range, defects and structural disorder readily form at the surface and affect device performance. Through concerted efforts to optimize processing techniques, high-quality perovskite thin films can now be fabricated with monolayer-like polycrystalline grains or even single crystals. Surface defects therefore remain the major obstacle to progress, pushing surface studies to the forefront of perovskite research. In this Review, we summarize and assess recent advances in the understanding of perovskite surfaces and surface strategies towards improving perovskite materials and the efficiency and stability of perovskite devices. The surface features of metal halide perovskites have a crucial role in determining their properties. This Review introduces the recent advances in the understanding of perovskite surfaces and surveys the surface strategies towards improving the properties of perovskite materials and the performance of perovskite optoelectronic devices.

Micro- and Nanostructured Lead Halide Perovskites: From Materials to Integrations and Devices.

In the past decade, lead halide perovskites have been intensively explored due to their promising future in photovoltaics. Owing to their remarkable material properties such as solution processability, nice defect tolerance, broad bandgap tunability, high quantum yields, large refractive index, and strong nonlinear effects, this family of materials has also shown advantages in many other optoelectronic devices including microlasers, photodetectors, waveguides, and metasurfaces. Very recently, the stability of perovskite devices has been improved with the optimization of synthesis methods and device architectures. It is widely accepted that it is the time to integrate all the perovskite devices into a real system. However, for integrated photonic circuits, the shapes and distributions of chemically synthesized perovskites are quite random and not suitable for integration. Consequently, controlled synthesis and the top-down fabrication process are highly desirable to break the barriers. Herein, the developments of patterning and integration techniques for halide perovskites, as well as the structure/function relationships, are systematically reviewed. The recent progress in the study of optical responses originating from nanostructured perovskites is also presented. Lastly, the challenges and perspective for nanostructured-perovskite devices are discussed.

Spontaneous Passivation of Perovskite Solar Cells by Titanium Tetrafluoride

The efficiency, stability, and scalability of perovskite devices still require further enhancement for real-world application. Defect passivation has been recognized as one prominent strategy that can simultaneously promote the optoelectronic performance and stability of perovskite devices. Here, we demonstrate an additive, titanium tetrafluoride (TiF4), which could spontaneously enrich at perovskite interfaces and passivate the nearby charge traps efficaciously. Consequently, a power conversion efficiency of 20.19% was attained on the basis of the passivated device with TiF4, about 22% enhancement over that of the control device without TiF4. Moreover, the moisture stability of PSCs with TiF4 was significantly enhanced.

Critical analysis of stability and performance of organometal halide perovskite solar cells via various fabrication method (Review)

Organometal halide perovskite solar cells (Omh-PSCs ) have attracted attention due to its unique electrical and optical properties. Ideally, the Omh-PSCs should remain free from degradation under normal operating conditions for several years, preferably tens of years. In order to produce high power conversion efficiency with low potential of degradation, different fabrication methods have been developed. The reported stability of perovskite films can vary significantly and reported to decay substantially up to 20% of its original performance. A thorough understanding of fabrication process upon the stability of the device is regarded as crucial to pave the way for future endeavors. This review summarized and highlighted the recent research of fabrication methods that gave an impact to the stability of perovskite devices.