Metal Halide Perovskite Materials Research Articles

Metal Halide Perovskites for Direct X‐Ray Detection in Medical Imaging: To Higher Performance

AbstractThis review discusses the utilization of metal halide perovskite (MHP) materials in X‐ray direct imaging detectors for medical application. Compared to traditional semiconductors, MHP has multiple advantages including high linear attenuation coefficient, low exciton binding energy, long carrier diffusion length, and high carrier mobility. These ascendancies allow for low‐dose and high‐resolution medical imaging. Apartment from a historical overview of the develop‐X‐ray direct imaging detectors and their performance indicators, this review specifically focuses on the development and innovation of X‐ray direct imaging detectors using MHP materials. The article concludes by identifying existing challenges and discussing the potential application of perovskite X‐ray direct imaging detectors in the medical industry.

Application of tiered human health and environmental risk assessment to develop safe and sustainable by design perovskite-based devices

Metal halide perovskite materials have gained significant attention in recent years due to their potential energy and lighting applications. They are potentially vital materials for the current energy transition which aims to minimize the dependence on fossil fuels and limited land resources by the increased use of cost-effective and efficient renewable energy sources. The European Green Deal policy, which sets out its ambitions in the Chemicals Strategy for Sustainability, can help its transition to a Safe and Sustainable by Design (SSbD) development. In this context, we applied the SSbD approach to selected perovskite-based devices which are still in their development state, by assessing potential human health and environmental risks along their life cycle. We applied the SSbD approach in a tiered manner so that it aligns with successive Technology Readiness Levels (TRL) to help the innovators ensuring safety and sustainability aspects throughout the various stages of their product development. Thus, the SSbD assessment began right from the start of the development (TRL 1–2), when there can be (huge) gaps and uncertainty in the product knowledge, up to the later stages of higher TRL when the product knowledge is more abundant and certain. In our assessment, we mainly focused on the human health risk of the perovskite-based devices and considered the implications of environmental emissions of hazardous substances on the human health. We further bring attention to the alternatives which could help mitigate concerns over their safety and sustainability for a responsible technology development and deployment. Results of this study are important to understand the detailed sustainability assessment in which we look at multiple sustainability aspects and its potential future impacts due to technology scale-up in the future.

Redox-Sensitive NiOx Stabilizing Perovskite Films for High-Performance Photovoltaics.

Metal halide perovskite materials inherently possess imperfections, particularly under nonequilibrium conditions, such as exposure to light or heat. To tackle this challenge, we introduced stearate ligand-capped nickel oxide (NiOx), a redox-sensitive metal oxide with variable valence, into perovskite intermediate films. The integration of NiOx improved the efficiency and stability of perovskite solar cells (PSCs) by offering multifunctional roles: (1) chemical passivation for ongoing defect repair, (2) energetic passivation to bolster defect tolerance, and (3) field-effect passivation to mitigate charge accumulation. Employing a synergistic approach that tailored these three passivation mechanisms led to a substantial increase in the devices' efficiencies. The target cell (0.12 cm2) and module (18 cm2) exhibited efficiencies of 24.0 and 22.9%, respectively. Notably, the encapsulated modules maintained almost 100 and 87% of the initial efficiencies after operating for 1100 h at the maximum power point (60 °C, 50% RH) and 2000 h of damp-heat testing (85 °C, 85% RH), respectively. Outdoor real-time tests further validated the commercial viability of the NiOx-assisted PSMs. The proposed passivation strategy provides a practical and uncomplicated approach for fabricating high-efficiency and stable photovoltaics.

Halide Exchange in Perovskites Enables Bromine/Iodine Hybrid Cathodes for Highly Durable Zinc Ion Batteries.

With the increasing need for reliable storage systems, the conversion-type chemistry typified by bromine cathodes attracts considerable attention due to sizeable theoretical capacity, cost efficiency, and high redox potential. However, the severe loss of active species during operation remains a problem, leading researchers to resort to concentrated halide-containing electrolytes. Here, profiting from the intrinsic halide exchange in perovskite lattices, a novel low-dimensional halide hybrid perovskite cathode, TmdpPb2[IBr]6, which serves not only as a halogen reservoir for reversible three-electron conversions but also as an effective halogen absorbent by surface Pb dangling bonds, C─H…Br hydrogen bonds, and Pb─I…Br halogen bonds, is proposed. As such, the Zn||TmdpPb2[IBr]6 battery delivers three remarkable discharge voltage plateaus at 1.21V (I0/I-), 1.47V (I+/I0), and 1.74V (Br0/Br-) in a typical halide-free electrolyte; meanwhile, realizing a high capacity of over 336 mAh g-1 at 0.4 A g-1 and high capacity retentions of 88% and 92% after 1000 cycles at 1.2 A g-1 and 4000 cycles at 3.2 A g-1, respectively, accompanied by a high coulombic efficiency of ≈99%. The work highlights the promising conversion-type cathodes based on metal-halide perovskite materials.

Electronic properties of individual CsPbI2Br nanocrystals investigated by LT-STM

Solution-processed metal halide perovskite nanocrystals show promise for various potential optoelectronic applications and the exploration of the fundamental physics underlying them. However, the electronic properties of individual nanocrystals have not been thoroughly studied. Here, we applied low-temperature scanning tunneling microscopy to investigate the properties of metal halide perovskite CsPbI2Br nanocrystals with a diameter in the range of 10–20 nm. Sub-monolayer dispersions of the nanocrystal on highly oriented pyrolytic graphite and gold thin film substrates were achieved. Using scanning tunneling microscopy, we resolved topographies of individual nanocrystals on the gold film, and their electronic properties were probed by scanning tunneling spectroscopy. In our experiment, no obvious dependence of the extracted energy gap on the nanocrystal size and shape was found, which is consistent with the reported small exciton Bohr radius in metal halide perovskite materials. Additionally, we observed that the energy gaps of some nanocrystals are smaller than that of the bulk, suggesting the influence of factors such as deep-level defects/traps, ion migration, etc. on the electronic structure.

Enhancing energy transfer via inhibition defect density of coupled quasi-2D perovskite layers for efficient sky-blue light-emitting diodes

Metal halide perovskite materials have emerged as unique and promising candidates for full-color display and solid-state lighting applications. While substantial progress has been made in developing green, red and near-infrared perovskite light-emitting diodes (PeLEDs) with external quantum efficiency (EQE) approaching their theoretical upper limit, the performance of blue PeLEDs is still lagging far behind. Here, synergistic long and short hydrobromide chains are strategically introduced into the perovskite to regulate composition and dimensional engineering for promoting coupled quasi-two-dimensional perovskite thin films with enhanced photoluminescence quantum yield (PLQY) and reduced trap state density. The inclusion of the hydrobromide can also simultaneously passivate the perovskite defects by reducing nonradiative recombination loss and increasing the formation of n >1 phases for efficient exciton energy transfer. Encouraged by these findings, we finally demonstrate the most stable sky-blue PeLEDs to date with a half-lifetime of 515 min at high external quantum efficiency (EQE＞10 %), emitting at 486 nm with a peak EQE of up to 15.6 %.

Mitigation of carrier trapping effects on carrier lifetime measurements with continuous-wave laser illumination for Pb-based metal halide perovskite materials

We investigated the impact of carrier trapping on the carrier lifetime of metal halide perovskite materials, which are key to solar cell production. We examined NH3CH3PbI3 (MAPbI3), NH3CH3PbBr3 (MAPbBr3), and CsPbBr3 using continuous-wave (CW) laser illumination during microwave photoconductivity decay (μ-PCD) measurements. Traditional pulsed light excitation falls short of mirroring solar cell operating conditions, owing to carrier trapping. Implementing CW laser illumination provides a more accurate estimation of the carrier lifetimes under operational conditions. With an increased photon flux from the CW laser, the μ-PCD decay curves changed, indicating reduced recombination via traps. The experiments revealed extended carrier lifetimes under continuous light for the MAPbI3 polycrystal. This suggests that CW lasers can mitigate trapping effects on carrier lifetime measurements. For the other samples, carrier trapping had a negligible effect on the measured carrier lifetimes. We believe that these findings will aid in the design of perovskite-based devices.

Hig‐Performance Green Quasi‐2D Perovskite Light‐Emitting Diodes via Passivated Defects

AbstractIn next generation semiconductors, metal halide perovskite materials would replace traditional light‐emitting materials since their exceptional photoelectronic characteristics. The future development of perovskite light‐emitting diodes have generated challenges such as abundant surface or interfacial defects and exciton quenching. To overcome these challenges, the light‐emitting layer is modified utilizing benzimidazole/phosphine oxide hybrid 1,3,5‐tris(1‐(4‐(diphenylphenylphosphoryl)phenyl)‐1H‐benzo[d]imidazol‐2‐yl)benzene (TPOB) and 1,3,5‐tris(diphenylphosphoryl)benzene (TPO) with high triple energy state. It is demonstrated by X‐ray photoelectron spectroscopy results that the oxygen atoms in the P = O functional group of TPOB and TPO provided lone electron pairs coordinate to the unsaturated Pb2+ in turn led to a decrease in the electron cloud density of Pb2+ and Br‐, which can suppress defects. Additionally, this technique improved the morphology of film, reduced surface roughness, and facilitated carrier transport, all of which are crucial for achieving high‐emission efficiency. As a result, the optimal devices has EQEs of 16.20 (TPOB) and 20.48% (TPO), respectively. Furthermore, the devices demonstrated excellent reproducibility. Excitingly, the champion EQE value for the optimal device is 22.64%. Simultaneously, it can increase the stability of the devices and the lifetimes are increased from 1231 s (Pristine) to 5421 (TPOB) and 5631 s (TPO).

Analysis of the bonding’s energy in metal-halide perovskites and brief evaluation of meta-GGA functionals TPSS and revTPSS

Metal-halide perovskites, known for their remarkable photovoltaic performance and ease of production, have garnered global attention in material science. Addressing scalability requires tackling the technology’s primary challenge: instability. Crucial insights into the complex chemistry of these materials are imperative for progress. The present study focused on well-known perovskites, namely CsPbI3, CH3NH3PbI3 and HC(NH2)2PbI3. Through both cohesive energy and ICOHP analysis, the chemical bonding of these compounds. Additionally, a comparative evaluation of the functionals of TPSS, revTPSS, HCTH/407, and PBE was made through bandgap determination. The key findings of this study were: i) having confirmed the predominantly ionic nature of lead halide interactions; ii) having pointed out the predominantly covalent nature of the molecules’ constituents binding; iii) having found that the strongest hydrogen bonds are formed by methylammonium; and iv) having nourished the utility of the TPSS meta-GGA functional in calculating the band gap of organic–inorganic perovskites. The results presented here could be important to the understanding and description of metal halide perovskite materials.

Mn(II)-Activated Zero-Dimensional Zinc(II)-Based Metal Halide Hybrids with Near-Unity Photoluminescence Quantum Yield.

As derivatives of metal halide perovskite materials, low-dimensional metal halide materials have become important materials that have attracted much attention in recent years. As one branch, zinc-based metal halides have the potential for practical applications due to their lead-free, low-toxicity and high-stability characteristics. However, pure zinc-based metal halide materials are still limited by their poor optical properties and cannot achieve large-scale practical applications. Therefore, in this work, we report an organic-inorganic hybrid zero-dimensional zinc bromide, (TDMP)ZnBr4, using transition metal Mn2+ ions as dopants and incorporating them into the (TDMP)ZnBr4 lattice. The original non-emissive (TDMP)ZnBr4 exhibits bright green emission under the excitation of external UV light after the introduction of Mn2+ ions with a PL peak position located at 538 nm and a PLQY of up to 91.2%. Through the characterization of relevant photophysical properties and the results of theoretical calculations, we confirm that this green emission in Mn2+:(TDMP)ZnBr4 originates from the 4T1 → 6A1 optical transition process of Mn2+ ions in the lattice structure, and the near-unity PLQY benefits from highly localized electrons generated by the unique zero-dimensional structure of the host material (TDMP)ZnBr4. This work provides theoretical guidance and reference for expanding the family of zinc-based metal halide materials and improving and controlling their optical properties through ion doping.

Lead-Free Double Perovskites: A Review of the Structural, Optoelectronic, Mechanical, and Thermoelectric Properties Derived from First-Principles Calculations, and Materials Design Applicable for Pedagogical Purposes

Metal halide perovskite materials have shown significant advancements in their application as light absorbers in perovskite solar cells, with power conversion efficiencies reaching 27%. However, lead-based perovskites pose a concern due to their toxicity and stability issues in moisture, UV radiation, and heat. This has led to a pressing need to explore substitute materials that do not contain lead but maintain the remarkable characteristics of lead-based perovskites. This review article focuses on halide double perovskites characterised by the A2B’B”X6 composition, highlighting their structural, optical, thermoelectric, and mechanical capabilities. Additionally, the review evaluates several materials databases to investigate materials suitable for high-throughput first-principles calculations integrated inside density functional theory. The review aims to identify novel perovskite materials, offer a thorough evaluation of the potential benefits and drawbacks associated with this class of materials, and, from the pedagogical standpoint, discover effective instructional frameworks.

Insights into the spectroscopic and structural features of methylammonium copper halide perovskites and theoretical view

This study encompasses a comprehensive investigation of stable metal halide perovskite materials, focusing on bandgap tuning, crystallization pathways, and the impact of moisture. In this work, we successfully synthesized different compositions of layered perovskites of methylammonium copper halides ((CH3NH3)2CuCl4). The morphology and structure were examined using a scanning electron microscope and x-ray diffractometer. Morphological and structural characterizations enhanced our understanding of the microstructure and crystallographic properties. A detailed structural characterization of the (CH3NH3)2CuCl4 was conducted using the Scherrer equation and the Williamson–Hall (W–H) method. To examine the effects of moisture on the optical properties of the samples, we used a UV–vis spectrophotometer, which provided valuable insight into their bandgap tuning. In addition, photoluminescence studies were conducted to investigate the blue fluorescence of the samples, demonstrating their efficacy in optoelectronic applications. We also explored the materials’ response to intense light using the Z-scan technique, examining their nonlinear optical properties. The findings of this study are pivotal in advancing our knowledge and facilitating the development of more stable and versatile perovskite materials for practical applications. Subsequently, simulations were conducted using the SCAPS-1D, a Solar Cell Capacitance Simulator, revealing a promising solar cell architecture with a glass substrate/FTO/zinc oxide (ZnO)/(CH3NH3)2CuCl4/spiro-OMeTAD/Au configuration, showcasing an impressive conversion efficiency of 27.93%, a fill factor of 84.16, Jsc of 34.39 mA cm−2, and Voc of 0.9 V.

Ultrastable Dual-Matrix meditated CsPbBr3 composites with enhanced photoluminescence quantum yield and robust circular polarization luminescence

Metal halide perovskite materials have emerged as a focal point of research in the field of circularly polarized luminescence (CPL). However, striking a delicate balance between several crucial parameters, including large luminescence dissymmetry factors (glum), high photoluminescence quantum yields (PLQY), and long-term stability, has proven to be a challenging endeavor. Here, this study presented a pioneering strategy for crafting robust CPL-active inorganic nanomaterial composites utilizing dual-matrix of chiral nematic mesoporous silica (CNMS) and inorganic passivation Cs4PbBr6 layer. The use of free-standing CNMS hard templates provided a confined growth environment for all-inorganic CsPbBr3 perovskite nanocrystals, enabling the conversion of unpolarized light emission into CPL. Through further advancements in the form of effective passivation with inorganic Cs4PbBr6 layer, superior optical performance and stability were achieved in the system. The figure of merit (FM) value for the resultant CsPbBr3/Cs4PbBr6@CNMS composite film reached −7.8 × 10−2, surpassing the performance of current advanced systems. Moreover, the surface passivation, along with the protection offered by the dual-matrix encapsulation, enhanced the resilience of composite film to harsh environments with robust performance. The successful integration of the CPL materials into a circularly polarized light-emitting diode device confirmed their applicability in CPL displays and luminescence applications. This work establishes a reliable and efficient method for the development of high-performance CPL materials and applications.

Perovskite Light-Emitting Devices Based on Solid-State Diffusion In Situ Dynamic Thermal Crystallization.

Due to the excellent photonic and electrical properties of metal halide perovskite materials, perovskite light-emitting devices have the potential to replace OLED devices as the next-generation of commercial light-emitting devices. In this article, we controlled the surface morphology of PbBr2 using an in situ dynamic thermal crystallization process, which increased the specific surface area of the films and promoted the solid-state diffusion rate. The CsPbBr3 PeLEDs prepared using this method achieved a maximum current efficiency of 7.1 cd/A at the voltage of 5 V, which was 200% higher than devices prepared using traditional spin-coating processes. These results proved that the in situ thermal dynamic crystallization process effectively improved the film quality of perovskite materials.

Study of a metal-halide perovskite CsPbBr3 thin film deposited on a 10B layer for neutron detection

Metal halide perovskite materials have received significant attention in recent years due to their promising properties and potential applications, particularly their use as scintillator detectors, which is rapidly emerging due to their promising advantages as detectors, such as low costs, fast response, high quantum yield, strong absorption, scalability, flexibility, and emission wavelength tunability. Given the effectiveness of perovskites as α particle detectors and the potential of 10B as a neutron converter, in this paper a 10B converting layer was coupled with an all-inorganic lead halide perovskite (CsPbBr3) layer aiming to create a thermal neutron detector. Specifically, a 1 µm thin film of 10B and a 1 µm thin layer of CsPbBr3 were deposited on a suitable substrate using a laser ablation process. The fabricated detector was subjected to a comprehensive characterization, including structural, morphological, and detection properties. As output, the films exhibit macroscopically uniform behavior and good adhesion to the substrate. In terms of thermal neutron efficiency, an efficiency of (7.9 ± 0.3)% was determined with respect to a commercial detector (EJ-426), which corresponds to an intrinsic efficiency of (2.5 ± 0.1)%. Also, Monte Carlo simulations were conducted, and the optimum value of the 10B layer thickness was found to be 2.5 µm.

Luminescent Behavior of Sb3+-Activated Luminescent Metal Halide.

Metal halide perovskites have unparalleled optoelectronic properties and broad application potential and are expected to become the next epoch-making optoelectronic semiconductors. Although remarkable achievements have been achieved with lead halide perovskites, the toxicity of lead inhibits the development of such materials. Recently, Sb3+-activated luminescent metal halide perovskite materials with low toxicity, high efficiency, broadband, large Stokes shift, and emission wavelengths covering the entire visible and near-infrared regions have been considered one of the most likely luminescent materials to replace lead halide perovskites. This review reviews the synthesis, luminescence mechanism, structure, and luminescence properties of the compounds. The basic luminescence properties of Sb3+-activated luminescent metal halide perovskites and their applications in WLED, electroluminescence LED, temperature sensing, optical anti-counterfeiting, and X-ray scintillators are introduced. Finally, the development prospects and challenges of Sb3+-activated luminescent metal halide perovskites are discussed.

Environmentally Friendly Perovskite‐Based Photovoltaics and Luminescence: Lead Less or Lead Free

Lead‐based metal halide perovskite materials have been rapidly developed for light‐emitting diodes, solar cells, and photodetectors owing to their excellent optoelectronic properties. Nevertheless, the presence of lead in these materials raises critical concerns regarding their environmental impact and potential toxicity, hindering their commercial development. In response to these concerns, researchers have devoted considerable effort toward the development of environmentally friendly perovskites. In this review, the theoretical evolution path and characteristics of lead‐substituted perovskites are first emphasized, as they contribute to the development of high‐performance lead‐free halide perovskites. Additionally, the current investigation of lead‐less and lead‐free perovskites including synthesis, optoelectronic properties, and applications is systematic summarized. Notably, the positive effects of both lead‐less and lead‐free perovskites on structure, optoelectronic properties, and associated devices in comparison to their lead‐based counterpart are emphasized. Finally, potential opportunities and challenges for future research into environmentally friendly perovskites and their applications are identified.

Recent Application and Progress of Metal Halide Perovskite Photodetector on Flexible Substrates

Comprehensive SummaryIn recent years, flexible photodetectors (FPDs) have received increasing attention due to their applications in electronic eyes, flexible sensing, terminal devices, and wearable devices. In addition, metallic halide perovskite materials are considered as future materials for FPDs due to their compatibility with flexible substrates, low cost, simple synthesis methods, and superior optoelectronic properties. This review provides a comprehensive overview of the relevant cutting‐edge research in the field of flexible perovskite photodetectors (FPPDs) from 2020 to 2022. First, the evaluation criteria for FPPDs are discussed and the development of perovskite stability criteria is emphatically described. Afterwards, the synthesis methods and device construction processes of metal halide perovskite materials commonly used by researchers in the past three years are described. These include single crystals and low‐dimensional materials. Moreover, we have elaborated on the research of self‐powered FPPD and its contributions in wearability, terminals, and portability. Finally, a summary of developments and possibilities in the field of FPPDs from 2020 to 2022 is provided.

Enhancing energy channel and carriers recycling in sky-blue perovskite light-emitting diodes via a fluorescent fortifier

Metal halide perovskite materials are renowned for their exceptional photoelectric properties, holding immense promise as next-generation luminescent materials. However, challenges, such as inferior film morphology, multidimensional phase coexistence, and energy level barrier hindrance, result in carrier transport imbalance and poor confinement. The presence of numerous defects in the light-emitting layer (EML) or at the interface leads to auger recombination, hindering the attainment of high-efficiency and stable devices. To address these issues, herein, we introduce a fluorescent material named t-DABNA-dtB in a hole transport layer (HTL) as a carrier catcher, leveraging the Förster channel to enhance energy and carrier utilization. Moreover, the reduction in energy level barriers between HTL and EML ensures balanced carrier transport within the EML and effectively suppresses trap-induced non-radiative losses. Consequently, the diminished density of defect states effectively curbs luminescence quenching, leading to enhanced device stability.

Machine‐Learning Accelerating the Development of Perovskite Photovoltaics

Perovskite solar cells (PSC) are a potential candidate for next‐generation photovoltaic technology. Despite the significant advancements in the field of PSCs, the ongoing development of stable and efficient metal halide perovskite materials, along with their successful integration into photovoltaic applications, remains challenges. These challenges originate from the diverse range of device structures and perovskite compositions, requiring meticulous consideration and optimization. Traditional trial‐and‐error methods are characterized by their sluggishness and labor‐intensive nature. Recently, the emergence of extensive datasets and advancements in computer hardware have facilitated the utilization of machine learning (ML) across multiple domains, including in various fields for material discovery and experimental optimization. Herein, the fundamental procedure of ML is briefly introduced, and latest progress of ML in the materials development and solar cell fabrication is comprehensively reviewed. The utilization of ML in PSCs at all stages of design can be categorized into four main areas: screening perovskite material, fabrication process optimization, device structure optimization, and understanding mechanism. The challenges and outlooks on the future development of ML are finally discussed. It is highly expected that this review can offer valuable guidance for the design and development of highly efficient and stable PSCs.