All-inorganic Perovskite Research Articles

Spin–orbital coupling in all-inorganic metal-halide perovskites: The hidden force that matters

Highlighted with improved long-term thermal and environmental stability, all-inorganic metal halide perovskites exhibit tunable physical properties, cost-effective synthesis, and satisfactory optoelectronic performance, attracting increasing research interest worldwide. However, a less explored feature of these materials is their strong spin–orbit coupling (SOC), which is the hidden force influencing not only band structure but also properties including magnetoresistance, spin lifetime, and singlet-triplet splitting. This review provides an overview of the fundamental aspects and the latest progress of the SOC and debate regarding Rashba effects in all-inorganic metal halide perovskites, providing critical insight into the physical phenomena and potential applications. Meanwhile, crystal structures and photophysics of all-inorganic perovskite are discussed in the context of SOC, along with the related experimental and characterization techniques. Furthermore, a recent understanding of the band topology in the all-inorganic halide perovskites is introduced to push the boundary even further for the novel applications of all-inorganic halide perovskites. Finally, an outlook is given on the potential directions of breakthroughs via leveraging the SOC in halide perovskites.

Investigation of NMR shielding, EFG and structural relaxation of all-inorganic Pb-based Ruddlesden Popper halide perovskites

Investigation of NMR shielding, EFG and structural relaxation of all-inorganic Pb-based Ruddlesden Popper halide perovskites

Encapsulation of CsPb2Br5 in TiO2 Microcrystals to Enhance Environmental Stability.

All-inorganic lead halide perovskite has emerged as an attractive semiconducting material due to its unique optoelectronic properties. However, its poor environmental stability restricts its broad application. Here, a simple method for the fabrication of CsPb2Br5/TiO2 is investigated. The introduction of p-aminobenzoic acid, which has two functional groups, is critical for the capping of amorphous TiO2 on CsPb2Br5. After calcination at 300 °C, amorphous TiO2 crystallizes into the anatase phase. The CsPb2Br5/TiO2 NCs show high long-term stability in water and enhanced stability against ultraviolet radiation and heat treatment, owing to the chemical stability of TiO2. More importantly, photo-electrochemical characterizations indicate that the formation of TiO2 shells can increase the charge separation efficiency. Hence, CsPb2Br5/TiO2 exhibits improved photoelectric activity owing to the electrical conductivity of the TiO2 in water. This study provides a new route for the fabrication of optoelectronic devices and photocatalysts based on perovskite NCs in the aqueous phase. Furthermore, the present results demonstrate that CsPb2Br5/TiO2 NCs has considerable potential to be used as a photoelectric material in optical sensing and monitoring.

Field-Induced Transport Anisotropy in Single-Crystalline All-Inorganic Lead-Halide Perovskite Nanowires

Field-Induced Transport Anisotropy in Single-Crystalline All-Inorganic Lead-Halide Perovskite Nanowires

Electrostatically anchored MXene-Thionine hybrid electrodes for a flexible supercapacitor to attain exceptional performance

Portable photorechargeable supercapacitors hold great promise as ideal power sources for future IoT applications. However, the widespread implementation of supercapacitors is hindered by their suboptimal energy density. Organic electrodes, with their high specific capacity, have become rising stars in the energy storage community. Herein, we pioneer an electrostatic-anchoring in situ polymerization reaction pathway to synthesize MXene-organic hybrid electrode materials. Theoretical calculations show that thionine (Th) is the optimal candidate for grafting onto the pseudocapacitive 2D MXene due to its low energy levels, narrow band gap, and multiple active sites. Multilevel interactions between Th and MXene are established to prevent Th from dissolution, to inhibit the MXene from restacking, and to facilitate electron accumulation in Th, thus enhancing the accessibility/absorption of ions in electrolytes and electrode stability. The hybrid electrodes exhibit a specific capacity as high as 4906.7 mF/cm2 at 1 mA cm−2; more importantly, an integrated asymmetric flexible supercapacitor displays high specific capacity (3183.1 mF/cm2) and large energy density (1432.4 mWh/cm2), all three values are the highest among their respective categories. Combining supercapacitors with all-inorganic perovskite solar cells to achieve rapid charge storage.

Compound doping enables efficient CsPbBr3 nanocrystal light emitting diodes

All-inorganic cesium-based perovskite nanocrystals (PeNCs) attract much attentions in displays due to their facile synthesis protocol and superior luminous performance, while material instability hinders their practical applications. Herein, by inducing a multi-functional dopant, i.e., SrBr2, into the perovskite precursor solution, the as-formed SrBr2-doped CsPbBr3 NCs possess purer phases, suppressed defects and hydrophobic surfaces, which leads to a high photoluminescence quantum yield of ∼90 %, as well as much improved moisture stability. Benefiting from dopant passivation and improved luminescence properties, the doped CsPbBr3 light emitting diodes show five times and two times of current efficiency and external quantum efficiency improvements, respectively, in comparison to their undoped counterparts.

Compositional Design for High-Efficiency All-Inorganic Tin Halide Perovskite Solar Cells

Compositional Design for High-Efficiency All-Inorganic Tin Halide Perovskite Solar Cells

Effect of addition of indium oxide layer on all-inorganic perovskite solar cells

In perovskite solar cells, the interface plays a crucial role in photovoltaic performance because excitons dissociate and compound at the interface. In this paper, the optical absorption layer of In2O3 planar perovskite solar cells is studied, which is an efficient intermediate layer between the TiO2 electron transport layer and perovskite. The modification of the In2O3 interlayer increases the average power conversion efficiency from 6.74% to 10.68%. Based on this background, some other feature descriptions are also carried out. The results show that the photovoltaic performance can be improved by depositing the In2O3 interlayer, mainly due to the improved film morphology, reduced recombination center, bulk carrier concentration and Hall mobility. It has been shown that In2O3 can be used as an efficient interface material on all-inorganic perovskite solar cells.

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.

Highly Anisotropic Polarization Induced by Electrical Poling in Single-Crystalline All-Inorganic Perovskite Nanoplates

Highly Anisotropic Polarization Induced by Electrical Poling in Single-Crystalline All-Inorganic Perovskite Nanoplates

Enhancing Luminescence in Hue-Tunable White-Light Emitting K4CdCl6:Sb3+,Mn2+ All-Inorganic Halide Perovskites: Insights from Defect Engineering and Energy Transfer.

All-inorganic halide perovskites (AIHPs) have emerged as highly promising optoelectronic materials owing to their remarkable properties, such as high-optical absorption coefficients, photoluminescence efficiencies, and dopant tolerance. Here, we investigate the AIHPs K4CdCl6:Sb3+,Mn2+ that demonstrate hue-tunable white-light emission with an exceptional photoluminescence quantum yield of up to 97%. Through a detailed investigation, we reveal that efficient energy transfer from Sb3+ to Mn2+ plays a dominant role in the photoluminescence of Mn2+, instead of the conventional 4T1g → 6A1g transition of Mn2+. Thermodynamic analysis highlights the crucial role of a Cl-rich environment in obtaining the K4CdCl6 phase, while transformation from K4CdCl6 to KCdCl3 can be achieved under Cl-poor and K-poor conditions. The theoretical analysis reveals that defect Cli is more readily formed compared to defect VK, corroborating experimental findings that the K4CdCl6:Sb3+ phase is exclusively obtained when the solution contains HCl concentrations higher than 4 mol L-1. Our work provides valuable insights into the photoluminescence mechanism of Sb3+, defect engineering through heterovalent doping, and efficient energy transfer between Sb3+ and Mn2+ in K-Cd-Cl-based perovskites, which offers a new perspective for the design and development of novel AIHPs with superior optoelectronic performance.

Enhanced luminescence stability of high-entropy dual-phase Cs(Pb1/5Mn1/5Ni1/5Zn1/5Cd1/5)Br3/Cs(Pb1/5Mn1/5Ni1/5Zn1/5Cd1/5)2Br5 perovskite nanocrystals coated with SiO2 and EVA

All-inorganic halide perovskite nanocrystals (NCs) have attracted much attention in many fields. However, the poor stability of NCs and the toxicity of Pb have greatly hindered their practical applications. Reducing the proportion of Pb with the concept of high-entropy and coating NCs with an outer layer have been regarded as effective strategies to solve the problems. Herein, We have successfully synthesized the all-inorganic high-entropy dual-phase Cs(Pb1/5Mn1/5Ni1/5Zn1/5Cd1/5)Br3/Cs(Pb1/5Mn1/5Ni1/5Zn1/5Cd1/5)2Br5(Cs‘B’Br3/Cs‘B’2Br5) perovskite NCs with good luminescence properties by a high-energy ball milling method; On the basis of which, Cs‘B’Br3/Cs‘B2’Br5 NCs are coated with SiO2 and EVA resin. Due to the amorphous SiO2 protection, the Cs‘B’Br3/Cs‘B2’Br5@SiO2 NCs maintained 93% of their emission intensity after 90 days compared to their uncoated counterparts. The PL intensity of Cs‘B’Br3/Cs‘B2’Br5 NCs /EVA was significantly enhanced by a factor of 4.7 for compared to the uncoated NCs. In addition, the PL emission intensity of the Cs‘B’Br3/Cs‘B2’Br5 NCs /EVA remained 93.7% after 90 days, and the emission peak intensity remained approximately 63% after 8 h of placement in an enclosed environment at 80% humidity through the dense polymer chains and the hydrophobic nature of the film. Finally, the film could expand its application prospects in the field of flexible device.

Precursor engineering enables high-performance all-inorganic CsPbIBr2 perovskite solar cells with a record efficiency approaching 13%

All-inorganic CsPbIBr2 perovskite has attracted widespread attention in photovoltaic and other optoelectronic devices because of its superior thermal stability. However, the deposition of high-quality solution-processed CsPbIBr2 perovskite films with large thicknesses remains challenging. Here, we develop a triple-component precursor (TCP) by employing lead bromide, lead iodide, and cesium bromide, to replace the most commonly used double-component precursor (DCP) consisting of lead bromide and cesium iodide. Remarkably, the TCP system significantly increases the solution concentration to 1.3 M, leading to a larger film thickness (∼390 nm) and enhanced light absorption. The resultant CsPbIBr2 films were evaluated in planar n-i-p structured solar cells, which exhibit a considerably higher optimal photocurrent density of 11.50 mA cm−2 in comparison to that of DCP-based devices (10.69 mA cm−2). By adopting an organic surface passivator, the maximum device efficiency using TCP is further boosted to a record efficiency of 12.8% for CsPbIBr2 perovskite solar cells.

Interface Engineering with Formamidinium Salts for Improving Ambient-Processed Inverted CsPbI3 Photovoltaic Performance: Intermediate- vs Post-Treatment.

Inverted all-inorganic perovskite solar cells (PSCs) have attracted increasing attention owing to excellent thermal stability, easy fabrication, and adaptable application as top cell in tandem solar cells. Apart from efficiency, ambient processing is desirable for practical production. To avoid water invasion in ambient air, surface engineering for perovskites is reported as a valid approach. However, most were performed by post-treatment, which hardly regulates the formation process of perovskite crystals. This work demonstrates a simple but effective surface intermediate-treatment strategy to stabilize CsPbI3 perovskites fabricated in ambient air and compares the different effects yielded on the inverted PSCs. By using formamidinium (FA) salts for intermediate-treatment, the strong interaction between FA cation and [PbI6]4- octahedron improves the moisture resistance, and compared with the post-treatment strategy, the accelerated crystallization rate and the shortened exposure time to moisture reduce the devastation by water during film fabrication process further. Moreover, the greatly passivated defects and optimized energy level matching between perovskite and PCBM suppress the nonradiative recombination. Resultantly, the optimized device shows enhanced efficiency from 11.39% to 15.45%, and long-term stability is improved, with 97.6% efficiency remaining after storage for 1600 h. Therefore, we believe that this work can provide a promising guideline for fabricating all-inorganic inverted PSCs in a low-cost manufacturing scheme.

Improvement of the performance of carbon based all-inorganic perovskite solar cells by using ammonium acetate modified rutile TiO2 nanorods array as the electron transport layer

Carbon-based all-inorganic perovskite solar cells are currently emerging as a commercial and promising photovoltaic device. Rutile TiO2 has the function of UV shielding and preventing the decomposition of perovskite, furthermore, TiO2 nanorod array provides the direct 1-D electron transmission channel. Herein, vertically oriented rutile TiO2 nanorods array are synthesized on the FTO substrate by a simple one-step hydrothermal process and used as the electron transfer layer. The analysis of characterization illustrates that the prepared TiO2 is a flawless single rutile phase. TiO2 nanorods are employed as an ETL to provide a passage for the rapid and direct charge transfer. The separation of electrons and holes can be enhanced by ammonium acetate treatment of the TiO2 nanorod ETL/perovskite interface, and the carrier recombination can be efficiently lowered. Based on the structure of FTO/TiO2@CH3COONH4/CsPbI2.25Br0.75/C, the best device containing 2.5 mg/mL ammonium acetate modified TiO2 nanorods showed a short-circuit current density of 14.55 mA/cm2, open-circuit voltage of 1.08 V, and fill factor of 69.45 %, yielding a power conversion efficiency of 11.53 %, which show an increase in efficiency of approximately 22.4% when compared with the control cell. The results show that ammonium acetate interface modification is an effective strategy to enhance the photovoltaic performance of PSCs.

Highly conducting Al-doped zinc oxide electron transport layer for all-inorganic perovskite solar cells: An experimental and simulation study

The need for an excellent electron transport layer (ETL) material is immensely significant for higher conversion efficiency of perovskite solar cells (PSCs). This work centers on the exceptional performance achieved by the Al-doped ZnO (AZO) ETL with reference to undoped ZnO (ZnO). Both doped and undoped ETL materials were synthesized and characterized to determine their structural, morphological, and optical behavior. In this work, solar cell performance of two similar CsPbIBr2-based PSCs with different ETLs namely FTO/ZnO/CsPbIBr2/NiO (Cell #1) and FTO/AZO/CsPbIBr2/NiO (Cell #2) are investigated through numerical simulation method. The obtained characteristics affirms that Cell #2 offers sufficient better performance parameters (Jsc, Voc, FF, and η) against Cell #1 with respect to variation in CsPbIBr2 PVT, ETL and HTL thickness. The adverse effect on J-V characteristics caused by controllable introduction of defect density (Nt) in PVT layer is negligible for Cell #2 compared to its ZnO counterpart. Further, the contribution of AZO ETL layer on cell's performance is evaluated in terms of variation in respective ETL and HTL thickness. The investigation reveals that Cell #2 offers a desirable η of 19.46% at electron capture cross section of 2 × 10−15 cm2 while Cell #1 delivers only 12.48%.

Low lead inorganic Zn-based mixed-halide perovskites CsPb0.625Zn0.375I3−β X β (X = Cl or Br) for energy generation with 23.5% efficiency

Hybrid perovskite (HP) solar cells have garnered significant attention in recent years for their excellent light absorption, long carrier lifetime, and high diffusion length, resulting in high power conversion efficiency and superior optical performance compared to silicon solar cells. However, the organic component in HP solar cells is vulnerable to thermal variations and the presence of lead (Pb) poses a threat to the environment. To address these issues, this work proposes the use of all-inorganic halide perovskite (IHP) materials with low lead content as the absorber layer in four different perovskite solar cell configurations: CsPb0.625Zn0.375I2Br, CsPb0.625Zn0.375IBr2, CsPb0.625Zn0.375I2Cl, CsPb0.625Zn0.375ICl2. In addition, owing to the consideration novel IHP materials, it is important to identify the appropriate properties of transport layers since conventional transport layers are best suited to conventional organic–inorganic halide perovskites and may not work well with proposed IHP. Therefore, the appropriate electron transport layer (ETL) has also been investigated through optimization of electron affinity (4.0 eV − 4.23 eV), mobility (0.004 cm2/Vs to 4 cm2/Vs), and donor doping density (1015 cm−3 to 1018 cm−3). The device performance has been further analysed and optimized by varying the active layer thickness. The selected ETL is then combined with the absorber layers to evaluate performance. The effect of varying the thickness of the absorption layer is observed in all four device arrangements. Simulation results show that CsPb0.625Zn0.375ICl2 performed best among the mentioned absorber materials, with a power conversion efficiency of 23.5% with ETL parameters of 4.00 eV (electron affinity, χ), 4 cm2/Vs (electron mobility, μ n), 1×1018 cm−3 (donor doping density, Nd) and absorber layer thickness of 500 nm. Proposed work may open a window for the development of a new class of environment friendly and stable perovskite solar cells in future.

Investigation of Vacancy-Ordered Double Perovskite Halides A2Sn1-xTixY6 (A = K, Rb, Cs; Y = Cl, Br, I): Promising Materials for Photovoltaic Applications.

In the present study, the structural, mechanical, electronic and optical properties of all-inorganic vacancy-ordered double perovskites A2Sn1-xTixY6 (A = K, Rb, Cs; Y = Cl, Br, I) are explored by density functional theory. The structural and thermodynamic stabilities are confirmed by the tolerance factor and negative formation energy. Moreover, by doping Ti ions into vacancy-ordered double perovskite A2SnY6, the effect of Ti doping on the electronic and optical properties was investigated in detail. Then, according to the requirement of practical applications in photovoltaics, the optimal concentration of Ti ions and the most suitable halide element are determined to screen the right compositions. In addition, the mechanical, electronic and optical properties of the selected compositions are discussed, exhibiting the maximum optical absorption both in the visible and ultraviolet energy ranges; thus, the selected compositions can be considered as promising materials for application in solar photovoltaics. The results suggest a great potential of A2Sn1-xTixY6 (A = K, Rb, Cs; Y = Cl, Br, I) for further theoretical research as well as experimental research on the photovoltaic performance of stable and toxic-free perovskite solar cells.

Scalable All-Inorganic Halide Perovskite Photoanodes with >100h Operational Stability Containing Earth-Abundant Materials.

The application of halide perovskites in the photoelectrochemical generation of solar fuels and feedstocks is hindered by the instability of perovskites in aqueous electrolytes and the use of expensive electrode and catalyst materials, particularly in photoanodes driving kinetically slow water oxidation. Here, solely earth-abundant materials are incorporated to fabricate a CsPbBr3 -based photoanode that reaches a low onset potential of +0.4 VRHE and 8mA cm-2 photocurrent density at +1.23 VRHE for water oxidation, close to the radiative efficiency limit of CsPbBr3 . This photoanode retains 100% of its stabilized photocurrent density for more than 100h of operation by replacing once the inexpensive graphite sheet upon signs of deterioration. The improved performance is due to an efficiently electrodeposited NiFeOOH catalyst on a protective self-adhesive graphite sheet, and enhanced charge transfer achieved by phase engineering of CsPbBr3 . Devices with >1 cm2 area, and low-temperature processing demonstrate the potential for low capital cost, stable, and scalable perovskite photoanodes.

High-performance all-inorganic perovskite light-emitting diodes enabled by a self-assembled molecule additive via defect passivation and strain relaxation

All-inorganic perovskite light-emitting diodes (AIPeLEDs) have been demonstrated with superior thermal stability than organic analogues, but the high defect density and lattice strain of all-inorganic perovskites commonly result in compromised efficiency and stability of the devices. Herein, a self-assembled molecule, 4-bromobenzoic acid (BBA), is adopted as an additive to modify CsPbBr3-based green AIPeLEDs. In particular, the formic acid group (-COOH) of BBA can interact with the uncoordinated Pb dangling bonds, leading to reduced defects and released lattice strain of perovskites, thereby facilitating the formation of all-inorganic perovskite films with a high photoluminescence quantum yield of 54.5 %. As a result, AIPeLEDs with a high maximum current efficiency of 42.4 cd A−1, and an external quantum efficiency of 11.4 % are obtained. Moreover, promoted by the inhibited non-radiative recombination and released lattice stress, the T50 lifetime (at an initial brightness of 200 cd m−2) is also improved from 2 h for the control PeLEDs to 8 h for the BBA-treated PeLEDs, which further confirms the superiority of BBA in passivating the AIPeLEDs.