Perovskite Thin Films Research Articles

Ligand‐Induced Crystallization Control in MAPbBr3 Hybrid Perovskites for High Quality Nanostructured Films

AbstractControlling the formation of hybrid perovskite thin films is crucial in obtaining high‐performance optoelectronic devices, since factors like morphology and film thickness have a profound impact on a film's functionality. For light‐emitting applications grain sizes in the sub‐micrometer‐range have previously shown enhanced brightness. It is therefore crucial to develop simple, yet reliable methods to produce such films. Here, a solution‐based synthesis protocol for the on‐substrate formation of MAPbBr3 (MA = methylammonium) nanostructures by adding the bifunctional rac‐3‐aminobutyric acid to the precursor solution is reported. This synthesis route improves key optical properties such as photoluminescence quantum yields and life times of excited states by inducing a controlled slow‐down of the film formation and suppressing agglomeration effects. In situ spectroscopy reveals a delayed and slowed down crystallization process, which achieves synthesis of perovskite structures with much reduced defect densities. Further, aggregation can be controlled by the amount of amino acid added and adjusting the synthesis protocol allows to produce cubic crystallites with targeted size from nanometer to micrometer scales. The nanocrystalline MAPbBr3 samples show enhanced amplified spontaneous emission (ASE) intensities, reduced ASE thresholds and purer ASE signals, compared to pristine films, even under intense optical driving, making them promising structures for lasing applications.

Robust Fully Screen‐printed Perovskite Solar Cells Based on Synergistic Ostwald Ripening

Fully screen‐printed process for low‐cost manufacturing significantly enhances the commercial competitiveness of perovskite solar cells (PSCs). However, the controllable crystallization in screen‐printed perovskite thin films using high ‐ viscosity ionic liquids has been suggested to be difficult, which hampers further development of fully screen‐printed perovskite devices in terms of application expansion and performance improvement. Here, we report a synergistic ripening strategy to fully control crystallization by employing methylamine propionate (MAPa) ionic liquid and water (H2O, moisture in the air). We found that a reversible and sustainable ripening process was activated by integrating MAPa/H2O in both externally and internally into perovskite crystals. MAPa effectively prevents the loss of organic salts and maintains the dispersion of Pb‐I framework, preventing the perovskite component loss and decomposition. H2O and organic salts trends to form hydration complexes, which lowers the energy barrier and enhances the reactivity of the humidity‐induced Ostwald ripening reaction. These improvements allow the perovskite films achieve controlled secondary growth, reducing defects and optimizing energy level alignment. The resulting fully screen‐printed PSCs exhibits a record power conversion efficiency of 19.47% and an operational stability over 1,000 h with maintaining 91.6% of the highest efficiency under continuous light stress at maximum power point.

Robust Fully Screen-printed Perovskite Solar Cells Based on Synergistic Ostwald Ripening.

Fully screen-printed process for low-cost manufacturing significantly enhances the commercial competitiveness of perovskite solar cells (PSCs). However, the controllable crystallization in screen-printed perovskite thin films using high - viscosity ionic liquids has been suggested to be difficult, which hampers further development of fully screen-printed perovskite devices in terms of application expansion and performance improvement. Here, we report a synergistic ripening strategy to fully control crystallization by employing methylamine propionate (MAPa) ionic liquid and water (H2O, moisture in the air). We found that a reversible and sustainable ripening process was activated by integrating MAPa/H2O in both externally and internally into perovskite crystals. MAPa effectively prevents the loss of organic salts and maintains the dispersion of Pb-I framework, preventing the perovskite component loss and decomposition. H2O and organic salts trends to form hydration complexes, which lowers the energy barrier and enhances the reactivity of the humidity-induced Ostwald ripening reaction. These improvements allow the perovskite films achieve controlled secondary growth, reducing defects and optimizing energy level alignment. The resulting fully screen-printed PSCs exhibits a record power conversion efficiency of 19.47% and an operational stability over 1,000 h with maintaining 91.6% of the highest efficiency under continuous light stress at maximum power point.

Organic Molecule Vapor‐Assisted Passivation for Efficient and Stable Perovskite Solar Cells

AbstractEffective suppression of non‐radiative recombination caused by surface defects in perovskite is crucial for achieving high‐efficiency perovskite solar cells (PSCs). However, conventional passivators such as organic amine salts are prone to deprotonation to amines and rapid reaction with formamidine, leading to device degradation. Meanwhile, the solvent processing of the organic amine salts can also decompose the surface of the perovskite layer due to the dissolution of the organic amine salts. In this work, an organic small molecule, 2‐Thiophenacetamide (TAM), features multiple active sites is presented. TAM demonstrates the ability to passivate perovskite thin films through sublimation deposition. It is demonstrated that this solvent‐free method and the effect of thiophene and the carbonyl group efficiently passivate the uncoordinated Pb2+, while the amino group aids in stabilizing perovskite structures by forming hydrogen bonds with iodide ions. As a result, the TAM vapor treatment device demonstrates an enhanced efficiency of 25.33%, and the operational stability is maintained at 95% of the original efficiency after continuous operation for over 1000 h. Additionally, perovskite submodules with an active area of 14 cm2 are successfully assembled with a efficiency of up to 22.17%.

Remote epitaxial crystalline perovskites for ultrahigh-resolution micro-LED displays.

The miniaturization of light-emitting diodes (LEDs) is pivotal in ultrahigh-resolution displays. Metal-halide perovskites promise efficient light emission, long-range carrier transport and scalable manufacturing for bright microscale LED (micro-LED) displays. However, thin-film perovskites with inhomogeneous spatial distribution of light emission and unstable surface under lithography are incompatible with the micro-LED devices. Continuous single-crystalline perovskite films with eliminated grain boundaries, stable surfaces and optical homogeneity are highly demanded for micro-LEDs, but their growth and device integration remain challenging. Here we realize the remote-epitaxy growth of crystalline perovskite films, enabling their seamless integration into micro-LEDs with a pixel size down to 4 μm. By incorporating a subnanometre graphene interlayer, we enable remote epitaxy and transfer of perovskites with relaxed strain. These micro-LEDs exhibit a high electroluminescence efficiency of 16.7% and a high brightness of 4.0 × 105 cd m-2. Such high performance stems from suppressed defects and efficient carrier transport in epitaxial perovskites with high crystallinity, relaxed strain and hundreds-of-nanometres thickness. The free-standing perovskites can be integrated with commercial electronic planes for independent and dynamic control of each pixel, thus facilitating both static image and video display. With these findings, we envision on-chip perovskite photonic sources such as ultracompact lasers and ultrafast LEDs.

Fabrication of high-performance tin halide perovskite thin-film transistors via chemical solution-based composition engineering.

Metal halide perovskite semiconductors have attracted considerable attention because they enable the development of devices with exceptional optoelectronic and electronic properties via cost-effective and high-throughput chemical solution processes. However, challenges persist in the solution processing of perovskite films, including limited control over crystallization and the formation of defective deposits, leading to suboptimal device performance and reproducibility. Tin (Sn2+) halide perovskite holds promise for achieving high-performance thin-film transistors (TFTs) due to its intrinsic high hole mobility. Nevertheless, reliable production of high-quality Sn2+ perovskite films remains challenging due to the rapid crystallization compared with more extensively studied lead (Pb)-based materials. Recently, composition engineering has emerged as a mature and effective strategy for realizing the high-yield fabrication of Sn2+ halide perovskite thin films. This approach cannot only achieve improved TFT performance with high hole mobilities and current ratios1-6, but also enable reliable device operation with hysteresis-free character and long-term stability7-12. Here we provide the experimental procedure for precursor preparation, film and device fabrication and characterization. The entire process typically takes 20-24 h. This protocol requires a basic understanding of metal halide perovskites, perovskite film coating process, standard TFT fabrication and measurement techniques.

Advances in Low Temperature Fabrication Strategies on Charge Carrier Transport Layers in Perovskite Solar Cells

Perovskite solar cells have garnered extensive attention and profound scrutiny from the global scientific community, attributed to their progressively enhancing photoelectric conversion efficiency, the expedient and efficient solution-based fabrication process, their distinctive lightweight and wearable attributes, and the promise of utilizing cost-effective materials. Over recent years, the efficiency of perovskite solar cells has surpassed the benchmark of 26.7%, while innovations in low-temperature synthesis techniques for crafting high-quality perovskite thin films were still calling efforts, coupled with relentless endeavors to refine the interface and electrode material designs. Simultaneously, the stability of these cells has garnered considerable industry focus. This paper delves into the latest advancements in the low-temperature preparation of perovskite solar cells, offering an insightful examination of pioneering methodologies and technical strategies for achieving low-temperature fabrication of each pivotal layer-specifically the carrier transport functional layers, while exploring a spectrum of enhancement strategies aimed at augmenting their performance further. These endeavors establish a robust foundation for their expanded applications in the foreseeable future.

Determining Parameters of Metal-Halide Perovskites Using Photoluminescence with Bayesian Inference

In this work, we demonstrate that time-resolved photoluminescence data of metal halide perovskites can be effectively evaluated by combining Bayesian inference with a Markov-chain Monte-Carlo algorithm and a physical model. This approach enables us to infer a high number of parameters that govern the performance of metal halide perovskite-based devices, alongside the probability distributions of those parameters, as well as correlations among all parameters. Via studying a set of halfstacks, comprising electron- and hole-transport materials contacting perovskite thin films, we determine surface recombination velocities at these interfaces with high precision. From the probability distributions of all inferred parameters, we can simulate intensity-dependent photoluminescence quantum efficiency and compare it to experimental data. Finally, we estimate mobility values for vertical charge-carrier transport, which is perpendicular to the plane of the substrate, for all samples using our approach. Since this mobility estimation is derived from charge-carrier diffusion over the length scale of the film thickness and in the vertical direction, it is highly relevant for transport in photovoltaic and light-emitting devices. Our approach of coupling spectroscopic measurements with advanced computational analysis will help speed up scientific research in the field of optoelectronic materials and devices and exemplifies how carefully constructed computational algorithms can derive valuable plurality of information from simple datasets. We expect that our approach can be expanded to a variety of other analysis techniques and that our method will be applicable to other semiconductors. Published by the American Physical Society 2025

Tuning electronic structure and carrier transport properties through crystal orientation control in two-dimensional Dion-Jacobson phase perovskites

Two-dimensional halide perovskites are attracting attention due to their structural diversity, improved stability, and enhanced quantum efficiency compared to their three-dimensional counterparts. In particular, Dion-Jacobson (DJ) phase perovskites exhibit superior structural stability compared to Ruddlesden-Popper phase perovskites. The inherent quantum well structure of layered perovskites leads to highly anisotropic charge transport and optical properties. Therefore, controlling the preferred crystal orientation (parallel or perpendicular) is crucial for optimizing device performance. This work presents a rational strategy to control parallel and perpendicular crystal growth in C6N2H16PbI4 (4AMPPbI4)-based DJ phase perovskite thin films. We demonstrate that crystal orientation depends on crystal growth rates, which can be controlled by varying the solvent composition, antisolvent, and annealing temperature. Direct and inverse photoelectron spectroscopy reveals that the electronic structure of 4AMPPbI4, including its work function, ionization energy, and electron affinity, is orientation-dependent. Different orientations significantly affect carrier transport as confirmed by single-carrier devices. This study highlights the critical role of crystal orientation in DJ phase perovskites for designing high-performance optoelectronic devices.Graphical

Improved Efficiency and Stability of Perovskite Solar Cells Through Long-Chain Phenylammonium Additives.

The addition of organic cationic iodides to form low-dimensional perovskite is an essential strategy for defect passivation in perovskite solar cells (PSCs). Specially, the 2D/3D perovskite structure can combine the stability of 2D perovskite and the high charge transport performance of 3D perovskite. Here, we introduced phenylammonium hydroiodide salts with different alkyl chain lengths into PSCs precursor solution to research the influence on formation of perovskite thin films and the photovoltaic performance of PSCs. As a result, the champion power conversion efficiency (PCE) of PSCs was increased to 22.68% by incorporation of the organic cation phenylpropyl ammonium iodide (PPAI) with the best alkyl chain length. We further fabricated the perovskite solar modules (PSMs) with an aperture area of 21 cm2, achieving an impressive efficiency of 21.65% with excellent stability that maintaining 89% of its initial efficiency after 1000 h of maximum power point tracking.

Optimization of neutron reflectometry experiment on thin films of hybrid perovskites for photovoltaics

Optimization of neutron reflectometry experiment on thin films of hybrid perovskites for photovoltaics

A facile approach for fabricating efficient and stable perovskite solar cells.

Perovskite solar cells (PSCs) with high power conversion efficiencies (PCEs) can be produced using a variety of methods, such as different fabrication methods, device layout modification, and component and interface engineering. The efficiency of a perovskite solar cell is largely dependent on the overall quality of the perovskite thin-film in every scenario. The utilization of spin-coating followed by the antisolvent pouring (ASP) method is prevalent in nearly all fabrication techniques to achieve superior perovskite thin-films. Nevertheless, there are a few guidelines that must be followed precisely when using the ASP approach, including the antisolvent amount, duration, and area for dropping. The aforementioned challenging and necessary strategies frequently result in perovskite thin-films with pinholes, tiny grains, and broad grain boundaries, which impair the performance of PSCs. Therefore, the implementation of a straightforward approach that does not require the use of such complex ASP steps is crucial. Here, we employ a simple process that involves the hot-dipping of lead iodide (PbI2) thin-films in a hot solution of methylammonium iodide (MAI) and formamidinium iodide (FAI) in isopropanol (IPA) to produce high-quality perovskite thin-films. As the time required for the desired perovskite to crystallize is critical, we carefully examined various hot-dipping process times, such as 10 seconds, 20 seconds, 30 seconds, and 40 seconds. These time intervals yielded thin-films, which were named PSK-10, PSK-20, PSK-30, and PSK-40, respectively. Morphological and optoelectronic characterization demonstrated the high quality of the perovskite thin-films obtained through dipping PbI2 for 30 seconds. Consequently, the PSK-30-based PSCs produced higher PCEs of up to 21.52% compared to those of the ASP-based devices (20.79%). Furthermore, the unsealed PSCs prepared with PSK-30 and ASP were assessed for 252 hours at 25 °C and 40-45% relative humidity in order to determine their operational stability. The ASP-based device showed poor stability, retaining only 10% of its original PCE, whereas the PSK-30-based device retained 70% of its initial PCE. These results offer a new and viable approach for producing highly efficient and stable PSCs.

Deep learning for augmented process monitoring of scalable perovskite thin-film fabrication.

Reproducible large-area fabrication is one of the remaining challenges for the commercialization of perovskite photovoltaics. Imaging methods augmented with deep learning (DL) enable in-line detection of spatial or temporal inconsistencies and predict the impact of observed changes on device performance. In this work, we showcase three use cases of how DL augments complex experimental data analysis of the large-area perovskite thin film formation, even on moderate-sized datasets. First, we demonstrate material composition monitoring by differentiating between precursor property variations, ensuring material consistency during fabrication. Second, we provide early thin-film quality assessment by predicting holistic device performance even before its finalization. Finally, we extend the approach from parameter prediction to generating recommendations for process control by forecasting monitoring signals as a function of a variable process parameter and predicting the corresponding device performances. By addressing tasks that are hardly possible for humans to solve, we present how DL augments data analysis by transforming experimental data into predictions of target parameters.

Bayesian optimization and prediction of the durability of triple-halide perovskite thin films under light and heat stressors

A machine learning regression model robustly predicts phase instability in wide bandgap halide perovskites by linking the spectral variation in 60-second photoluminescence tests to tests under 800 h, 1-sun, 85 °C conditions.

Towards highly efficient and stable perovskite solar cells: suppressing ion migration by inorganic boric acid stabilizer

The poor stability of organic-inorganic perovskite solar cells is commonly ascribed to elevated ion migration, stemming from the low electronegativity of iodine. To address this issue, boric acid was chosen as a stabilizer for perovskite thin films. As a Lewis acid, the boric acid has a sp2 hybridized boron atom, which can readily accept a pair of electrons from iodine ion into their vacant unhybridized p orbital, and the formation of the Pb-O bond further increases the iodide migration barrier. The significantly increased barrier of the iodine ion migration was demonstrated by the improved phase stability of the perovskite film under an electric field and the obviously enhanced stability of the perovskite films under strong ultraviolet light. PSCs that included the BA stabilizer were able to achieve an enhanced PCE of 25.52%. The initial efficiency of BA-modified devices remained at 80% even after being aged for 1000hours at 85 ℃ under around 30% relative humidity (RH). When subjected to maximum power point tracking and 20-25% RH, the PCE of BA-modified devices maintained an initial efficiency of 80% after 1500hours.

Vapor–Solid Reaction Techniques for the Growth of Organic–Inorganic Hybrid Perovskite Thin Films

AbstractPerovskite solar cells are considered next‐generation photovoltaic technology due to their remarkable advancements in power conversion efficiency. To transition this technology from the lab to industry, the method for preparing perovskite thin films must support mass production. Currently, the solution‐based slot‐die technique is the primary method for depositing large‐area perovskite thin films. However, solution‐based methods are not standard in the semiconductor industry, where vapor‐based techniques are favored for their high controllability and reproducibility. The cost of vacuum facilities and the complexity of these processes hinder many researchers, resulting in vapor‐based technique development lagging behind solution‐based methods in device efficiency and scale. This review focuses on the progress in growing perovskite thin films using vapor–solid reaction techniques, which are believed to offer the most direct path to commercialization. By examining the crystallization and growth mechanisms of perovskite films and discussing specific optimization strategies for vapor–solid reactions, insights into future developments and challenges in fabricating perovskite solar cells using fully vacuum processes are concluded.

High Performance of Cs2AgBiBr6 Perovskite-based Photodetectors by Adding DEAC.

Perovskite-based photodetectors (PDs) are broadly utilized in optical communication, non-destructive testing, and smart wearable devices due to their ability to convert light into electrical signals. However, toxicity and instability hold back their mass production and commercialization. The lead-free Cs2AgBiBr6 double perovskite film, promised to be an alternative, is fabricated by electrophoretic deposition (EPD), which compromises film quality. Herein, we improved the quality of the Cs2AgBiBr6 films and the performance of PDs by adding N-acetylethylenediamine (DEAC) to Cs2AgBiBr6 perovskite precursor for EPD, in which the ligand DEAC provides a pair of lone electrons to Bi3+, forming coordinate covalent bonds. The optimized PDs have high detectivity, up to 4.4×1012 Jones, and high stability in the air. The high-performance, flexible Cs2AgBiBr6 perovskite PDs were fabricated on this basis, it also achieved the detectivity up to 3.2×1012 Jones with excellent bending cycle stability. These results propose a feasible approach to improving the crystallization of double perovskite thin films by introducing ligands during the EPD process. Furthermore, they demonstrate enhanced optoelectronic performance, indicating that this method is also applicable to halide perovskites, offering an effective strategy to improve their film quality.

Influence of 5‑ammonium valeric acid iodide additive on the structural and optical behaviors of methylammonium lead tri-iodide perovskite thin films

Influence of 5‑ammonium valeric acid iodide additive on the structural and optical behaviors of methylammonium lead tri-iodide perovskite thin films

Perovskite Solar Cells: Structure, Working Principle, and Modification Strategy

Perovskite solar cells (PSCs) are known for their excellent photoelectric conversion efficiency, low cost, and high flexibility. Organic-inorganic hybrid PSCs have excellent performance which is comparable to traditional solar cells. However, the crystal quality of perovskite thin films is poor. In addition, there are numerous interface defects in the films, which lead to the unstable performance. Therefore, exploring ways to modify PSCs is beneficial for expanding their application realms. This work mainly discusses the development of perovskite solar cell. The structures of PSCs are discussed. The components and working principles of PSCs are described in detail. Perovskite films exhibit many defects, especially at the interface. These defects hinder the movement of charge carriers. As a result, the lifetime of charge carriers is largely reduced. Defect passivation technology can help improve this situation. Therefore, this work also introduces the modification strategies of PSCs including the additive engineering and interface engineering. In addition, exploring two-dimensional perovskite materials as one of the effective ways of modification has also been summarized. This work opened up a new perspective for the study of PSCs.

Iron-irradiated methylammonium lead iodide bromide (MAPbI2Br) thin films with enhanced optical and electrical properties for high-efficiency perovskite solar cells

In the pursuit of enhancing the optoelectronic properties of perovskite thin films for photovoltaic applications, this study investigates the effects of Fe ion irradiation on methylammonium lead iodide bromide (MAPbI₂Br) thin films. Thin films of methylammonium lead iodide bromide, (CH3NH3PbI2Br, or MAPbI2Br) have been deposited by sol–gel dip coating technique. These films were irradiated with 300 keV Fe ions with flouncy of 2 × 1014 ions/cm2. The prepared films all show the cubic crystal structure. However, the film irradiated with Fe ions has a larger grain size, according to XRD. The optical characteristics, such as refractive index, band gap energy, and extinction coefficients, are examined by UV–Vis analysis. Although both the films showed a direct bandgap, the film irradiated with Fe ions showed a lower value for the bandgap energy (1.76 eV) and high refractive index. The device structure used was FTO/TiO2/MAPbI2Br/spiro-OMeTAD/Au. The devices made with 300 keV Fe ions irradiated film has high current density of 10.86 mA cm−2, fill factor of 0.80, an open circuit voltage of 1.06 V, and an efficiency of 9.93%. The findings emphasize the potential of Fe ion irradiation as a novel technique to improve grain structure and optoelectronic properties, advancing perovskite-based device technology for higher efficiency solar cells.