Organometal Halide Perovskite Research Articles

Chemical Reaction of FA Cations Enables Efficient and Stable Perovskite Solar Cells.

Organometal halide perovskite solar cells (PSCs) have received great attention owing to a rapid increase in power conversion efficiency (PCE) over the last decade. However, the deficit of long-term stability is a major obstacle to the implementation of PSCs in commercialization. The defects in perovskite films are considered as one of the primary causes. To address this issue, isocyanic acid (HNCO) is introduced as an additive into the perovskite film, in which the added molecules form covalent bonds with FA cations via a chemical reaction. This chemical reaction gives rise to an efficient passivation on the perovskite film, resulting in an improved film quality, a suppressed non-radiation recombination, a facilitated carrier transport, and optimization of energy band levels. As a result, the HNCO-based PSCs achieve a high PCE of 24.41% with excellent storage stability both in an inert atmosphere and in air. Different from conventional passivation methods based on coordination effects, this work presents an alternative chemical reaction for defect passivation, which opens an avenue toward defect-mitigated PSCs showing enhanced performance and stability.

SCAPS-1D simulated organometallic halide perovskites: A comparison of performance under Sub-Saharan temperature condition

Photovoltaic technology has been widely recognized as a means to advance green energy solutions in the sub-Saharan region. In the real-time operation of solar modules, temperature plays a crucial role, making it necessary to evaluate the thermal impact on the performance of the solar devices, especially in high-insolation environments. Hence, this paper investigates the effect of operating temperature on the performance of two types of organometallic halide perovskites (OHP) - formamidinium tin iodide (FASnI3) and methylammonium lead iodide (MAPbI3). The solar cells were evaluated under a typical Nigerian climate in two different cities before and after graphene passivation. Using a one-dimensional solar capacitance simulation software (SCAPS-1D) program, the simulation results show that graphene passivation improved the conversion efficiency of the solar cells by 0.51 % (FASnI3 device) and 3.11 % (MAPbI3 device). The presence of graphene played a vital role in resisting charge recombination and metal diffusion, which are responsible for the losses in OHP. Thermal analysis revealed that the MAPbI3 device exhibited an increased fill factor (FF) in the temperature range of 20–64 °C, increasing the power conversion efficiency (PCE). This ensured that the MAPbI3 solar cell performed better in the city and the season with harsher thermal conditions (Kaduna, dry season). Thus, MAPbI3 solar cells can thrive excellently in environments where the operating temperature is below 65 °C. Overall, this study shows that the application of OHP devices in sub-Saharan climatic conditions is empirically possible with the right material modification.

Stability enhancement of perovskite solar cells using multifunctional inorganic materials with UV protective, self cleaning, and high wear resistance properties

Organometal halide perovskite solar cells have reached a high power conversion efficiency of up to 25.8% but suffered from poor long-term stability against environmental factors such as ultraviolet irradiation and humidity of the environment. Herein, two different multifunctional transparent coatings containing AZO and ZnO porous UV light absorbers were employed on the front of the PSCs. This strategy is designed to improve the long-term stability of PSCs against UV irradiation. Moreover, the provided coatings exhibit two additional roles, including self-cleaning and high wear resistance. In this regard, AZO coating showed higher wear resistance compared to the ZnO coating. The photocatalytic self-cleaning properties of these prepared coatings make them stable against environmental pollutants. Furthermore, appropriate mechanical properties such as high hardness and low coefficient of friction that leads to high resistance against wear are other features of these coatings. The devices with AZO/Glass/FTO/meso-TiO2/Perovskite/spiro/Au and ZnO/Glass/FTO/meso-TiO2/Perovskite/spiro/Au configurations maintained 40% and 30% of their initial performance for 100 h during 11 days (9 h per day) against the UV light with the high intensity of 50 mW cm-2 which is due to higher absorption of AZO compared with ZnO in the ultraviolet region. Since AZO has a higher light transmission in the visible region in comparison to ZnO, perovskite cells with AZO protective layers have higher efficiency than perovskite cells with ZnO layers. It is worth noting that the mentioned features make these coatings usable for cover glass in all types of solar cells.

Controlling growth of lead halide perovskites on organic semiconductor buffer layers

The performance of perovskite solar cells (PSCs) has been greatly influenced by the surface morphology and orientational growth of organometal halide perovskite, which can be controlled by buffer layers located underneath the perovskite layer. In this study, organic semiconductors such as rubrene and pentacene were selected as the buffer layer materials. We deposited CH3NH3PbI3 (MAPbI3) layers by the laser evaporation method onto the rubrene/pentacene bilayer, pentacene single layer, and rubrene single layer, respectively. The MAPbI3-based solar cell with the rubrene/pentacene bilayer showed a better cell performance compared to other PSCs with rubrene and pentacene single buffer layers. The better PSC performance can be presumably attributed to an orientational growth behavior and a smoother surface of MAPbI3 thin film on the rubrene/pentacene bilayer, as well as a more efficient hole transport in the organic bilayer.

Exploring Non-Toxic Lower Dimensional Perovskites for Next-Generation X-Ray Detectors.

Owing to their extraordinary photophysical properties, organometal halide perovskites are emerging as a new material class for X-ray detection. However, the existence of toxic lead makes their commercialization questionable and should readily be replaced. Accordingly, several lead alternatives have been introduced into the framework of conventional perovskites, resulting in various new perovskite dimensionalities. Among these, Pb-free lower dimensional perovskites (LPVKs) not only show promising X-ray detecting properties due to their higher ionic migration energy, wider and tunable energy bandgap, smaller dark currents, and structural versatility but also exhibit extended environmental stability. Herein, first, the structural organization of the PVKs (including LPVKs) is summarized. In the context of X-ray detectors (XDs), the outstanding properties of the LPVKs and active layer synthesis routes are elaborated afterward. Subsequently, their applications in direct XDs are extensively discussed and the device performance, in terms of the synthesis method, device architecture, active layer size, figure of merits, and device stability are tabulated. Finally, the review is concluded with an in-depth outlook, thoroughly exploring the present challenges to LPVKs XDs, proposing innovative solutions, and future directions. This review provides valuable insights into optimizing non-toxic Pb-free perovskite XDs, paving the way for future advancements in the field.

Long-chain organic molecules enable mixed dimensional perovskite photovoltaics: a brief view.

The remarkable optoelectronic properties of organometal halide perovskite solar cells have captivated significant attention in the energy sector. Nevertheless, the instability of 3D perovskites, despite their extensive study and attainment of high-power conversion efficiency, remains a substantial obstacle in advancing PSCs for practical applications and eventual commercialization. To tackle this issue, researchers have devised mixed-dimensional perovskite structures combining 1D and 3D components. This innovative approach entails incorporating stable 1D perovskites into 3D perovskite matrices, yielding a significant improvement in long-term stability against various challenges, including moisture, continuous illumination, and thermal stress. Notably, the incorporation of 1D perovskite yields a multitude of advantages. Firstly, it efficiently passivates defects, thereby improving the overall device quality. Secondly, it retards ion migration, a pivotal factor in degradation, thus further bolstering stability. Lastly, the inclusion of 1D perovskite facilitates charge transport, ultimately resulting in an elevated device efficiency. In this succinct review, we thoroughly encapsulate the recent progress in PSCs utilizing 1D/3D mixed-dimensional architectures. These advancements encompass both stacked bilayer configurations of 1D/3D structures and mixed monolayer structures of 1D/3D. Additionally, we tackle critical challenges that must be surmounted and offer insights into the prospects for further advancements in this domain.

Light-enhanced oxygen degradation of MAPbBr3 single crystal.

Organometal halide perovskites are promising materials for optoelectronic applications, whose commercial realization depends critically on their stability under multiple environmental factors. In this study, a methylammonium lead bromide (MAPbBr3) single crystal was cleaved and exposed to simultaneous oxygen and light illumination under ultrahigh vacuum (UHV). The exposure process was monitored using X-ray photoelectron spectroscopy (XPS) with precise control of the exposure time and oxygen pressure. It was found that the combination of oxygen and light accelerated the degradation of MAPbBr3, which could not be viewed as a simple addition of that by oxygen-only and light-only exposures. The XPS spectra showed significant loss of carbon, bromine, and nitrogen at an oxygen exposure of 1010 Langmuir with light illumination, approximately 17 times of the additive effects of oxygen-only and light-only exposures. It was also found that the photoluminescence (PL) emission was much weakened by oxygen and light co-exposure, while previous reports had shown that PL was substantially enhanced by oxygen-only exposure. Measurements using a scanning electron microscope (SEM) and focused ion beam (FIB) demonstrated that the crystal surface was much roughened by the co-exposure. Density functional theory (DFT) calculations revealed the formation of superoxide and oxygen induced gap state, suggesting the creation of oxygen radicals by light illumination as a possible microscopic driving force for enhanced degradation.

Ultrafast hole relaxation between dual valence bands in methylammonium lead iodide

Hybrid organometal halide perovskites have attracted much attention owing to their high conversion efficiencies in solar cell applications. Besides this, hybrid organometal halide perovskites have also been demonstrated to be...

Halide Perovskites-Based Diffusive Memristors for Artificial Mechano-Nociceptive System.

Numerous efforts for emulating organ systems comprised of multiple functional units have driven substantial advancements in bio-realistic electronics and systems. The resistance change behavior observed in diffusive memristors shares similarities with the potential change in biological neurons. Here, the diffusive threshold switching phenomenon in Ag-incorporated organometallic halide perovskites is utilized to demonstrate the functions of afferent neurons. Halide perovskites-based diffusive memristors show a low threshold voltage of ≈0.2V with little variation, attributed to the facile migration of Ag ions uniformly dispersed within the halide matrix. Based on the reversible and reliable volatile threshold switching, the memristors successfully demonstrate fundamental nociceptive functions including threshold firing, relaxation, and sensitization. Furthermore, to replicate the biological mechano-nociceptive phenomenon at a system level, an artificial mechano-nociceptive system is built by integrating a diffusive memristor with a force-sensing resistor. The presented system is capable of detecting and discerning the detrimental impact caused by a heavy steel ball, effectively exhibiting the corresponding sensitization response. By further extending the single nociceptive system into a 5 × 5 array, successful stereoscopic nociception of uneven impulses is achieved in the artificial skin system through array-scale sensitization. These results represent significant progress in the field of bio-inspired electronics and systems.

Light-induced micro-strain regulation and charge carrier dynamics of (FA0.83MA0.17)0.95Cs0.05Pb(I0.83Br0.17)3 hybrid perovskite films

Light-induced strategies are crucial for deciding the physical and chemical properties of organometal halide perovskite materials and their photovoltaic devices. Herein, the triple cation ((FA0.83MA0.17)0.95Cs0.05Pb(I0.83Br0.17)3) hybrid perovskite films have been fabricated using a simple solution-processed method. These films were illuminated by blue light (417 nm) for different time durations and characterized for structural, surface morphological, optical, and charge carrier dynamics. Under illumination conditions, a reduction in lattice micro-strain has been observed. The enhanced optical absorbance and reduced non-radiative recombination have also been monitored in light-illuminated perovskite films. Further, time-resolved photoluminescence (TRPL) and ultra-fast transient absorption spectroscopy (TAS) measurements have been performed to study the charge carrier dynamics. TRPL results show that the average lifetime of charge carriers has increased from 3 ns to 19 ns upon continuous light illumination conditions. Further, the recombination time of the charge carriers decreased from 226 ps to 66 ps upon continuous light illumination for 30 min. This study suggests that light-induced experiments on perovskite films can be utilized for micro-strain regulation and modulation of their charge carrier dynamics for future perovskite solar cell applications.

The Scale Effects of Organometal Halide Perovskites.

Organometal halide perovskites have achieved great success in solution-processed photovoltaics. The explorations quickly expanded into other optoelectronic applications, including light-emitting diodes, lasers, and photodetectors. An in-depth analysis of the special scale effects is essential to understand the working mechanisms of devices and optimize the materials towards an enhanced performance. Generally speaking, organometal halide perovskites can be classified in two ways. By controlling the morphological dimensionality, 2D perovskite nanoplatelets, 1D perovskite nanowires, and 0D perovskite quantum dots have been studied. Using appropriate organic and inorganic components, low-dimensional organic-inorganic metal halide hybrids with 2D, quasi-2D, 1D, and 0D structures at the molecular level have been developed and studied. This provides opportunities to investigate the scale-dependent properties. Here, we present the progress on the characteristics of scale effects in organometal halide perovskites in these two classifications, with a focus on carrier diffusion, excitonic features, and defect properties.

Modelling of Germanium-Based Perovskite Solar Cell for Different Hole Transport Materials and Defect Density

The performance of four distinct materials (organic and inorganic) was simulated and analyzed as hole transport layer (HTL) in the design of germanium (Ge)-based Perovskite Solar Cell (PSC). A 1-dimensional numerical software (SCAPS 1-D) has been applied to simulate the HTL candidates: spiro-OMeTAD, PTAA, nickel oxide (NiO), and copper (I) thiocyanate (CuSCN), with tin (IV) dioxide (SnO2) as the electron transport layer (ETL). The thickness of the methylammonium germanium iodide (CH3NH3GeI3) absorber was varied from 300 nm to 1100 nm, and the highest simulated power conversion efficiency was achieved at a thickness of 800 nm for all HTL candidates. It was observed that the inorganic CuSCN outperformed its counterparts with a power conversion efficiency (PCE) of 25.38%. The effect of the perovskite absorber’s defect density was investigated, and ultimately, it was demonstrated that this value is disproportionately related to the PCE. A reduction of nearly 98% in PCE was recorded when the defect density increased from 1x1014 cm-3 to 1x1020 cm-3. Additionally, for a constant ETL thickness of 80 nm, it was revealed that the PCE would decrease slightly, ranging from 0.1% to 0.3%, with an increase in HTL thickness from 50 nm to 300 nm. Comparing the PCE of our current work with published reports further justifies its competitiveness. Full Text: PDF References W.R. Becquerel, "Becquerel Photovoltaic Effect in Binary Compounds", J. Chem. Phys. 32, 1505 (1960). CrossRef A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka, "Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells", J. Am. Chem. Soc. 131, 6050 (2009). CrossRef M.M. Salah, K.M. Hassan, M. Abouelatta, A. Shaker, "A comparative study of different ETMs in perovskite solar cell with inorganic copper iodide as HTM", Optik 178, 958 (2019). CrossRef S. Rai, B. Pandey, A. Garg, D. Dwivedi, "Hole transporting layer optimization for an efficient lead-free double perovskite solar cell by numerical simulation", Opt. Mater, 121, 111645 (2021). CrossRef H. Liangsheng, Z. Min, S. Yubao, M. Xinxia, W. Jiang, Z. Qunzhi, F, Zaiguo, L. Yihao, H. Guoyu, L. Tong, "Tin-based perovskite solar cells: Further improve the performance of the electron transport layer-free structure by device simulation", Sol. Energy, 230, 345 (2021). CrossRef K. Fatema, M. Arefin, "Enhancing the efficiency of Pb-based and Sn-based perovskite solar cell by applying different ETL and HTL using SCAPS-ID", Opt. Mater. 125, 112036 (2022). CrossRef P. Patel, "Device simulation of highly efficient eco-friendly CH3NH3SnI3 perovskite solar cell", Sci. Rep., 11, 3082 (2021). CrossRef P. Roy, Y. Raoui, A. Khare, "Design and simulation of efficient tin based perovskite solar cells through optimization of selective layers: Theoretical insights", Opt. Mater., 125, 112057 (2022). CrossRef A.I. Azmi, M.Y. Mohd Noor, M.H.I. Ibrahim, F. Ahmad, M.H. Ibrahim, "A Numerical Simulation of Transport Layer Thickness Effect in Tin-Based Perovskite Solar Cell", JJEE, 8, 355 (2022). CrossRef A.A. Kanoun, M.B. Kanoun, A.E. Merad, S. Goumri-Said, "Toward development of high-performance perovskite solar cells based on CH3NH3GeI3 using computational approach", Sol. Energy, 182, 237 (2019). CrossRef A. Hima, N. Lakhdar, "Enhancement of efficiency and stability of CH3NH3GeI3 solar cells with CuSbS2", Opt. Mater., 99, 109607 (2020). CrossRef S.T. Jan, M. Noman, "Influence of layer thickness, defect density, doping concentration, interface defects, work function, working temperature and reflecting coating on lead-free perovskite solar cell", Sol. Energy, 237, 29 (2022). CrossRef

Organometal Halide Perovskite-Based Photoelectrochemical Module Systems for Scalable Unassisted Solar Water Splitting.

Despite achievements in the remarkable photoelectrochemical (PEC) performance of photoelectrodes based on organometal halide perovskites (OHPs), the scaling up of small-scale OHP-based PEC systems to large-scale systems remains a great challenge for their practical application in solar water splitting. Significant resistive losses and intrinsic defects are major obstacles to the scaling up of OHP-based PEC systems, leading to the PEC performance degradation of large-scale OHP photoelectrodes. Herein, a scalable design of the OHP-based PEC systems by modularization of the optimized OHP photoelectrodes exhibiting a high solar-to-hydrogen conversion efficiency of 10.4% is suggested. As a proof-of-concept, the OHP-based PEC module achieves an optimal PEC performance by avoiding major obstacles in the scaling up of the OHP photoelectrodes. The constructed OHP module is composed of a total of 16 OHP photoelectrodes, and a photocurrent of 11.52mA is achieved under natural sunlight without external bias. The successful operation of unassisted solar water splitting using the OHP module without external bias can provide insights into the design of scalable OHP-based PEC systems for future practical application and commercialization.

A novel, eco‐friendly film preparation process for improving the stability of organometal halide perovskite in solar cells

AbstractA major challenge for outdoor uses of methylammonium lead halide (MAPbX3) solar cells is the poor durability of the perovskite film under humidity. This instability is due to limitations of the dipping or spin coating process in producing MAPbX3 films through a direct reaction between PbI2 and methylammonium iodide (MAI) in an organic solvent. In this study, we devised an eco‐friendly and cost‐effective method to fabricate MAPbX3 films using an aqueous solution of Pb(NO3)2 and MAI vapour. In both instances of using Pb(NO3)2 and PbI2, a perovskite layer with a tetrahedral structure was seen with a band gap of roughly 1.52‐1.54 eV. We discovered that the perovskite film grew at a slower rate with aqueous Pb(NO3)2 compared to that in PbI2 and disintegrated gradually at ambient temperature and 40% humidity. Compared to PbI2 films‐based solar cells under the same reaction time, those based on aqueous Pb(NO3)2 films showed remarkably higher durability (maintain 83% for Pb(NO3)2 films‐based, 78% for PbI2 films‐based after 720 hours) and greater photovoltaic efficiency with the photocurrent density of 10.1 mA.cm‐2, the voltage of 0.89 V, the fill factor of 0.82 and PCE of 7.4% which is higher than PbI2 cells 30%.

Facet-Dependent Photoelectrochemistry on Single Crystal Organic-Inorganic Halide Perovskite Electrodes.

Organometallic halide perovskites have garnered significant attention in various fields of material science, particularly solar energy conversion, due to their desirable optoelectronic properties and compatibility with scalable fabrication techniques. It is often unclear, however, how carrier generation and transport within complex polycrystalline films are influenced by variations in local structure. Elucidating how distinct structural motifs within these heterogeneous systems affect behavior could help guide the continued improvement of perovskite-based solar cells. Here, we present studies applying scanning electron microscopy (SECCM) to map solar energy harvesting within well-defined model systems of organometallic halide perovskites. Methylammonium lead bromide (MAPbBr3) single crystals were prepared via a low-temperature solution-based route, and their photoelectrochemical properties were mapped via SECCM using p-benzoquinone (BQ) in dichloromethane as a redox mediator. Correlated SECCM mapping and electron microscopy studies enabled facet-to-facet variations in photoelectrochemical performance to be revealed and carrier transport lengths to be evaluated. The photoelectrochemical behavior observed within individual single crystals was quite heterogeneous, attributable to local variations in crystal structure/orientations, intrafacet junctions, and the presence of other structural defects. These observations underscore the significance of controlling the microstructure of single perovskite crystals, presenting a promising avenue for further enhancement of perovskite-based solar cells.

Designing an Efficient Lead-Free Perovskite Solar Cell through a Computational Method

Organometallic halide perovskite (PVK)-based solar cells (PSC) have gained significant popularity owing to their efficiency, adaptability, and versatility. However, the presence of lead in conventional PVK poses environmental risks and hinders effective commercialization. Although lead-free PVK solar cells have been developed, their conversion efficiency is limited due to intrinsic losses. To address this challenge, we present a simulation study focusing on methylammonium tin bromide (MASnBr3) as an alternative material. In our investigation, the MASnBr3 layers are strategically placed between a copper iodide (CuI)-based hole transporting material (HTM) and a zinc oxide (ZnO)-based electron transporting material (ETM). We optimize the active layer thickness, operating temperature, defect density analysis, and series resistances to assess device performance. Furthermore, we employ contour mapping, considering both thickness and defect density, for a detailed investigation. Our primary objective is to achieve unprecedented efficiency in lead-free MASnBr3-based PSCs. Remarkably, our study achieves the highest JSC (short-circuit current density) of 34.09 mA/cm2, VOC (open-circuit voltage) of 1.15 V, FF (fill factor) of 82.06%, and optimized conversion efficiency of 32.19%. These advancements in conversion efficiency pave the way for the development of lead-free PVK solar cells in the desired direction.

Unveiling the potential of organometal halide perovskite materials in enhancing photodetector performance

Unveiling the potential of organometal halide perovskite materials in enhancing photodetector performance

Organometal Halide Perovskite CH3NH3PbI3as an Effective Photosensitizer for p-Type Solar Cells

Organometal Halide Perovskite CH3NH3PbI3as an Effective Photosensitizer for p-Type Solar Cells

Tunable charge injection from graphene to halide perovskite induced by reversible ion segregation

Migration of point defects can result in various performance instabilities in organometal halide perovskite devices. In particular, the segregation of charged defects can influence the electron transport, but the correlation between ionic and electronic transports remains elusive. In this work, we use a graphene/methylammonium lead iodide capacitor to probe the effect of ion segregation on the charge injection behavior at the graphene/perovskite junction. In our samples, the ion segregation in the perovskite film is induced by a controllable electric field applied through an electrostatic gate. At the same time, the charge injection from graphene to the perovskite is probed by monitoring changes in the graphene conductivity. It is found that a positive (negative) defect accumulation layer near the graphene/perovskite interface can facilitate electron (hole) injection from the graphene electrode to the perovskite. Because the polarity of the defect accumulation layer is switchable by changing the direction of the applied electric field, the graphene/perovskite interface behaves like a Schottky junction with a tunable charge injection barrier height. This behavior should be generally found in other metal/halide perovskite interfaces as well.

Direct Observation of Contact Reaction Induced Ion Migration and its Effect on Non-Ideal Charge Transport in Lead Triiodide Perovskite Field-Effect Transistors.

The migration of ionic defects and electrochemical reactions with metal electrodes remains one of the most important research challenges for organometal halide perovskite optoelectronic devices. There is still a lack of understanding of how the formation of mobile ionic defects impact charge carrier transport and operational device stability, particularly in perovskite field-effect transistors (FETs), which tend to exhibit anomalous device characteristics. Here, the evolution of the n-type FET characteristics of one of the most widely studied materials, Cs0.05 FA0.17 MA0.78 PbI3, is investigated during repeated measurement cycles as a function of different metal source-drain contacts and precursor stoichiometry. The channel current increases for high work function metals and decreases for low work function metals when multiple cycles of transfer characteristics are measured. The cycling behavior is also sensitive to the precursor stoichiometry. These metal/stoichiometry-dependent device non-idealities are correlated with the quenching of photoluminescence near the positively biased electrode. Based on elemental analysis using electron microscopy the observations can be understood by an n-type doping effect of metallic ions that are created by an electrochemical interaction at the metal-semiconductor interface and migrate into the channel. The findings improve the understanding of ion migration, contact reactions, and the origin of non-idealities in lead triiodide perovskite FETs.