Bismuth Halide Perovskite Research Articles

Effect of Absorber Layer Thickness on the Performance of Bismuth-Based Perovskite Solar Cells

Theoretical study of methyl-ammonium bismuth halide perovskite solar cells, (CH3NH3)3Bi2I9, was carried out using a one-dimensional Solar Cell Capacitance Simulator (SCAPS-1D) software. The performance of the tested device architectures largely depends on the thickness of the absorbing layer, with the combination of electron transport, and hole transport layers. Thus, the bismuth perovskite absorber layer was optimized by varying the thickness and also, the thicknesses of the different charge-transport materials such as Spiro-OmeTAD, copper (I) oxide (Cu2O), and copper (I) iodide (CuI) as hole transport layer (HTL), and phenyl-C61-butyric acid methyl ester (PCBM), poly(3-hexylthiophene-2,5-diyl) (P3HT), zinc oxide, and titanium dioxide as electron transport layer (ETL). The best performance in terms of the power conversion efficiency (PCE) was recorded for the device with Cu2O as the HTL and ZnO as the ETL with the absorber layer thickness of 200 nm. The working temperature of the device was varied from 295 to 320 K and the effects of temperature on various device architectures were investigated. Results obtained indication that the efficiency of the bismuth perovskite solar cells can be improved by optimizing the thickness of the absorber layer and utilizing an appropriate combination of HTLs and ETLs. Keywords: methyl-ammonium bismuth perovskite, SCAPS, HTL, ETL, PCE.

Efficient near-infrared emission from lead-free ytterbium-doped cesium bismuth halide perovskites

Yb doping of Cs3Bi2Br9 results in near-infrared luminescence with 14.5% quantum yield when excited with above bandgap photons. This emission decreases sharply when bandgap is reduced below twice the emission energy raising the possibility that the mechanism involves quantum cutting.

Dimethylammonium iodide stabilized bismuth halide perovskite photocatalyst for hydrogen evolution

Metal halide perovskites have emerged as novel and promising photocatalysts for hydrogen generation. Currently, their stability in water is a vital and urgent research question. In this paper a novel approach to stabilize a bismuth halide perovskite [(CH3)2NH2]3[BiI6] (DA3BiI6) in water using dimethylammonium iodide (DAI) without the assistance of acids or coatings is reported. The DA3BiI6 powder exhibits good stability in DAI solutions for at least two weeks. The concentration of DAI is found as a critical parameter, where the I- ions play the key role in the stabilization. The stability of DA3BiI6 in water is realized via a surface dissolution–recrystallization process. Stabilized DA3BiI6 demonstrates constant photocatalytic properties for visible light-induced photo-oxidation of I- ions and with PtCl4 as a co-catalyst (Pt-DA3BiI6), photocatalytic H2 evolution with a rate of 5.7 μmol⋅h-1 from HI in DAI solution, obtaining an apparent quantum efficiency of 0.83% at 535 nm. This study provides new insights on the stabilization of metal halide perovskites for photocatalysis in aqueous solution.

Large-Grained All-Inorganic Bismuth-Based Perovskites with Narrow Band Gap via Lewis Acid-Base Adduct Approach.

Bismuth halide perovskites have recently been considered a potential alternative to lead halide analogues due to their low toxicity and high stability. However, the layered flake structure and wide band gap limit their applications in perovskite solar cells (PSCs). We herein show that large-grained all-inorganic bismuth-based perovskites with a narrow band gap can be obtained from a Lewis acid-base adduct reaction under ambient conditions. Thiourea (CH4N2S) is utilized as a Lewis base to interact with BiI3, confirmed with infrared (IR) spectra. The strong coordination between thiourea and the Bi3+ center could slow down the perovskite crystallization and promote the preferred orientation of the perovskite crystals with a hexagonal phase. The morphology of the perovskite films varies dramatically with an increase of molar ratio of BiI3 and thiourea in the precursor. The perovskites derived from a BiI3/thiourea ratio of 1:2 display extrathick grains, higher surface coverage, extended light absorption, higher crystallinity, and similar air stability compared to the pristine sample. The power conversion efficiency (PCE) of the thiourea-induced bismuth perovskite solar cells is significantly enhanced due to the higher surface coverage and the broader absorption of the perovskite film.

Self-Powered and Broadband Lead-Free Inorganic Perovskite Photodetector with High Stability.

Metal halide perovskite materials have opened up a great opportunity for high-performance optoelectronic devices owing to their extraordinary optoelectronic properties. More than lead halide ones, stable and nontoxic bismuth halide perovskites exhibit more promise in their future commercialization. In this work, we developed for the first time photodetectors based on full-inorganic Cs3Bi2I9-xBrx perovskites and modulate their performance by varying x in the composition systematically. Among those self-powered photodetectors, those based on Cs3Bi2I6Br3 shows the best performance with excellent photosensitivity of 4.1 × 104 at zero bias as well as the responsivity and detectivity reaching 15 mA/W and 4.6 × 1011 Jones, respectively. More strikingly, the full-inorganic perovskite photodetectors exhibit excellent stability in the ambient environment and can maintain over 96% of the initial value after 100 days owing to the high stability of the core perovskite film. The paper definitely paves an alternative and promising strategy for the design of future commercial photodetectors that are self-powered, stable, nontoxic, etc.

Enhanced photoconversion efficiency in cesium-antimony-halide perovskite derivatives by tuning crystallographic dimensionality

Lead-based perovskites have reached prominence in optoelectronic and photovoltaic research, yet their toxicity has prompted the search for alternative lead-free compounds. All-inorganic antimony-/bismuth-halide perovskite derivatives have been identified as a promising class of materials. Despite attractive bulk optoelectronic properties, their optoelectronic device performance has been lagging behind. Here we examine one of their most promising embodiments, the all-inorganic cesium-antimony-halide system. Through solution-based halide mixing, we achieve its structural conversion from a zero-dimensional to a layered phase at processing temperatures <150 °C, i.e., much lower than those relied upon in the prior literature (≥230 °C) of all-inorganic cesium-antimony halides. In order to evaluate the technological significance of this finding, we integrate our layered films into a sandwich-type device structure, and characterize their external quantum efficiency and photovoltaic behavior. We find that the structural conversion leads to a considerable enhancement in the optoelectronic device performance. Additionally, photocurrent-power characterization and Hall effect measurements reveal that this performance enhancement is brought about by an improvement in charge carrier transport, which can be exploited due to the unoriented nature of our low-temperature-processed layered films. Such performance boost and mechanistic insight constitute an important step in realizing the full potential of these (and related) compounds for their application in lead-free optoelectronic and photovoltaic devices, e.g., for top-cell in tandem photovoltaics, indoor photovoltaics, and photodetectors.

Synthesis and characterization of inorganic K3Bi2I9 perovskite thin films for lead-free solution processed solar cells

Bismuth halide perovskites have been proposed as a non-toxic and chemically stable alternative to lead halide perovskites. Despite being highly stable, the devices based on bismuth perovskites have not been able to compete with the lead counterparts in terms of its efficiencies. The compounds that have been extensively studied i.e. Cs3Bi2I9 and MA3Bi2I9 form 0D (dimer) structures that possess wide indirect band gaps and poor charge transport properties which hinders the performance of devices based on these materials. Theoretical studies have revealed that replacing bigger A cation like Cs/MA by smaller cation like potassium (K) could favor the formation of layered 2D structures rather than 0D structure. We have synthesized inorganic K3Bi2I9 perovskite thin films by facile one-step spin coating method and investigated its structural, optical and morphological properties. The fabricated films showed strong absorption in UV and visible region of solar spectrum and possess optical band gap ∼2 eV. On comparison with the Cs analogue, it is observed that reduction in the cation size (Cs to K) hardly changes the band gap of K3Bi2I9 films which implies that the band gap of A3Bi2I9 perovskite is insensitive to A-site variation. Films deposited on preheated substrates showed comparatively good coverage without voids on the film surface. Our preliminary studies on this material showed that the films deposited by one-step solution method favored 0D structure rather than the expected 2D layered structure.

Rigid Amine-Induced Pseudo-3 D Lead-Free Bismuth Halide Perovskite with an Improved Band Edge for Visible-Light Absorption.

Bismuth organometal halide perovskites have recently been investigated as potential substitutes for lead perovskite solar-cell absorbers because of their lower toxicity. However, the narrowing of the band gap remains a crucial challenge for their practical application. All known Bi-based perovskites have large band gaps, thereby affording weak visible-light absorption. This study concerns a novel, lead-free, pseudo-3 D perovskite optoelectronic material, (MV)BiI5 (MV2+ =methyl viologen). The pseudo-3 D metal-halogen perovskite-like structure is constructed by connecting [BiI5 ] 2+ units via I⋅⋅⋅I contacts. MV, as a rigid organic amine, is located at the center of each parallelepiped to balance the charge and stabilize the structure. (MV)BiI5 has a narrow band gap of 1.48 eV and a better photoresponse than (MV)BiCl5 with a 1 D structure. (MV)BiI5 is the first Bi-based perovskite compound with a band gap energy comparable with (CH3 NH3 )PbI3 , which is encouraging for optoelectronic applications. This research will open a potential pathway for the design of pseudo-3 D Bi-based perovskites with performances comparable with APbX3 absorbers.

A Supported Bismuth Halide Perovskite Photocatalyst for Selective Aliphatic and Aromatic C–H Bond Activation

AbstractDirect selective oxidation of hydrocarbons to oxygenates by O2 is challenging. Catalysts are limited by the low activity and narrow application scope, and the main focus is on active C−H bonds at benzylic positions. In this work, stable, lead‐free, Cs3Bi2Br9 halide perovskites are integrated within the pore channels of mesoporous SBA‐15 silica and demonstrate their photocatalytic potentials for C−H bond activation. The composite photocatalysts can effectively oxidize hydrocarbons (C5 to C16 including aromatic and aliphatic alkanes) with a conversion rate up to 32900 μmol gcat−1 h−1 and excellent selectivity (&gt;99 %) towards aldehydes and ketones under visible‐light irradiation. Isotopic labeling, in situ spectroscopic studies, and DFT calculations reveal that well‐dispersed small perovskite nanoparticles (2–5 nm) possess enhanced electron–hole separation and a close contact with hydrocarbons that facilitates C(sp3)−H bond activation by photoinduced charges.

A Supported Bismuth Halide Perovskite Photocatalyst for Selective Aliphatic and Aromatic C-H Bond Activation.

Direct selective oxidation of hydrocarbons to oxygenates by O2 is challenging. Catalysts are limited by the low activity and narrow application scope, and the main focus is on active C−H bonds at benzylic positions. In this work, stable, lead‐free, Cs3Bi2Br9 halide perovskites are integrated within the pore channels of mesoporous SBA‐15 silica and demonstrate their photocatalytic potentials for C−H bond activation. The composite photocatalysts can effectively oxidize hydrocarbons (C5 to C16 including aromatic and aliphatic alkanes) with a conversion rate up to 32900 μmol gcat −1 h−1 and excellent selectivity (>99 %) towards aldehydes and ketones under visible‐light irradiation. Isotopic labeling, in situ spectroscopic studies, and DFT calculations reveal that well‐dispersed small perovskite nanoparticles (2–5 nm) possess enhanced electron–hole separation and a close contact with hydrocarbons that facilitates C(sp3)−H bond activation by photoinduced charges.

Can perovskite inspired bismuth halide nanocrystals outperform their lead counterparts?

In the quest for finding non-toxic and stable lead-free perovskite nanocrystals (NCs), bismuth halide perovskites (BHP) have emerged as a promising alternative. This perspective presents an overview, challenges, and future opportunities in BHP NCs.

Bismuth halide perovskite derivatives for direct X-ray detection

A one-dimensional bismuth-based perovskite derivative (DMEDA)BiI5 was investigated for X-ray photoelectric detection.

An Improved Strategy for High-Quality Cesium Bismuth Bromine Perovskite Quantum Dots with Remarkable Electrochemiluminescence Activities.

Low-toxic trivalent bismuth, with an isoelectronic structure (6s26p0) and a similar ionic radius to divalent lead, represents a promising candidate for constructing lead-free perovskites. Herein, cesium bismuth halide perovskite quantum dots (Cs3Bi2Br9 QDs) were synthesized via a comprehensively improved ligand-assisted reprecipitation method with the addition of γ-butyrolactone, trace distilled water, and tetrabutylammonium bromide, as well as the aid of ultrasonic technology. The as-prepared QDs displayed remarkable monodispersity, outstanding stability, and highly passivated surfaces with a near-single-component PL decay, thus affording superb optical properties with a photoluminescence quantum yield up to 37%, outperforming all the reported bismuth-based perovskites. Furthermore, Cs3Bi2Br9 QDs were first attempted for electrochemiluminescence (ECL) and exhibited a stable and efficient ECL response following either an annihilation or a coreaction ECL mechanism. Not only were the optical properties and stability of Cs3Bi2Br9 QDs greatly improved in this work, but their electrochemical behaviors and ECL natures were also investigated systematically for the first time, demonstrating the significant potential to extend this environmentally friendly bismuth-based perovskite into the ECL domain.

Lead-Free Cs3 Bi2 Br9 Perovskite as Photocatalyst for Ring-Opening Reactions of Epoxides.

Herein, an innovative approach was developed by using stable, lead-free halide perovskite for solar-driven organic synthesis. The ring-opening reaction of epoxides was chosen as a model system for the synthesis of value-added β-alkoxy alcohols, which require energy-intensive process conditions and corrosive, strong acids for conventional synthesis. The developed concept included the in situ preparation of Cs3 Bi2 Br9 and its simultaneous application as photocatalyst for epoxide alcoholysis under visible-light irradiation in air at 293 K, with exceptional high activity and selectivity ≥86 % for β-alkoxy alcohols and thia-compounds. The Cs3 Bi2 Br9 photocatalyst exhibited good stability and recyclability. In contrast, the lead-based perovskite showed a conversion rate of only 1 %. The origin of the unexpected catalytic behavior was attributed to the combination of the photocatalytic process and the presence of suitable Lewis-acidic centers on the surface of the bismuth halide perovskite photocatalyst.

Solution-Processed Bismuth Halide Perovskite Thin Films: Influence of Deposition Conditions and A-Site Alloying on Morphology and Optical Properties.

Bismuth-based halide perovskites have been proposed as a potential nontoxic alternative to lead halide perovskites; however, they have not realized suitable performance. Their poor performance has been attributed to substandard film morphologies and too wide of a band gap for many applications. Herein we used a two-step deposition procedure to convert BiI3 thin films into A3Bi2I9 (A = FA+, MA+, Cs+, or Rb+), which resulted in a substantial improvement in film morphology, a larger band gap, and greater compositional tunability compared toresults when using aconventional single-step depositiontechnique. Additionally, we attempted to reduce the undesirably wide band gap inRb3Bi2I9thin filmsby inducing chemical pressures through cation-size mismatch,with an underlying hypothesis that cation-size mismatchcould inducecompressive strain within the 2D Rb3Bi2I9 lattice. However, we found that all A xRb3- xBi2I9 compositions with x > 0 adopted the 0D structure, and no changes to the band gap were observed with alloy. These results imply that the band gap ofA xRb3- xBi2I9is insensitive to A-site alloying.

Green solvent assisted synthesis of cesium bismuth halide perovskite nanocrystals and the influences of slow and fast anion exchange rates.

Replacing lead in halide perovskites to address the concerns of their toxicity and stability has driven a recent surge in research toward alternative lead-free perovskite materials. Lead-free all inorganic cesium bismuth halide (Cs3Bi2X9) perovskite nanocrystals have attracted attention in recent years due to the air-stability and non-toxic nature of bismuth. Herein, we demonstrate a facile sonication-assisted approach for the preparation of all-inorganic cesium bismuth iodide (Cs3Bi2I9) perovskite nanocrystals (NCs) using propylene carbonate as a green, alternative solvent. The photoluminescence (PL) spectra of the Cs3Bi2X9 NCs have a peak emission that can be tuned from 410 to 550 nm by controlling the composition of the NCs through an anion exchange reaction using tetraalkylammonium halides as a source of halide ions. The rate of this anion exchange reaction is demonstrated to have a significant influence on the dimensions of the NCs obtained from the parent Cs3Bi2I9 NCs. The PL emission of these nanocrystals is predominately due to exciton recombination processes. The NCs also exhibit air-stability for at least 150 days.

Lead-free formamidinium bismuth perovskites (FA)3Bi2I9 with low bandgap for potential photovoltaic application

Bismuth halide perovskites are potential lead-free absorbing materials for solar cells. However, methylamine and cesium-based bismuth perovskites are insufficient for visible light absorption because of their large bandgaps. In this work, we developed a new formamidinium (FA)-based bismuth perovskite material, (FA)3Bi2I9. (FA)3Bi2I9 shows a hexagonal phase with an enlarged unit cell than the conventional methylamine-based bismuth perovskite (MA)3Bi2I9. It has a bandgap of 2.19 eV and a Wannier–Mott exciton binding energy of 260 meV, which are lower than those of (MA)3Bi2I9 (2.25 eV and 320 meV, respectively) in our experiments. Thus, (FA)3Bi2I9 is more suitable as an absorbing layer for solar cells than (MA)3Bi2I9. In addition, solvents can effectively control the growth of (FA)3Bi2I9 films. In specific, using dimethyl sulfoxide as the solvent resulted in enhanced c-axis oriented growth and plate-like microstructure. With these bismuth perovskite films as absorbing layers, mesoporous-structured (FA)3Bi2I9 solar cells were fabricated for the first time. The initial devices show the highest open voltage of 0.48 V and a power conversion efficiency of 0.022%, which are higher than those of methylamine-based bismuth perovskite solar cells, offering a potential candidate for lead-free perovskite solar cells.

Lead-free, air-stable hybrid organic-inorganic perovskite resistive switching memory with ultrafast switching and multilevel data storage.

Organolead halide perovskites exhibit excellent optoelectronic and photovoltaic properties such as a wide range of light absorption and tunable band gaps. However, the presence of toxic elements and chemical instability under an ambient atmosphere hindered lead halide perovskites from real device applications because of environmental issues and stability. Here, we demonstrate a resistive switching memory device based on a lead-free bismuth halide perovskite (CH3NH3)3Bi2I9 (MABI). The active layer of the device can be easily prepared by solvent engineering. The nonvolatile memory based on MABI layers has reliable retention properties (∼104 s), endurance (300 cycles), and switching speed (100 ns), as well as environmental stability. Moreover, the control of the compliance current leads to multilevel data storage with four resistance states, which can be applied to high-density memory devices. These results suggest that MABI has potential applications in information storage.

Formation of highly luminescent cesium bismuth halide perovskite quantum dots tuned by anion exchange.

Cs3Bi2Br9 quantum dots (QDs) with photoluminescence quantum yields (PLQYs) of up to 22% were prepared through the steady binding of octylammonium bromide and oleic acid. Excellent thermal stability and good luminescence properties have been achieved as intrinsic features of the inorganic halide perovskites, as well as the effective passivation of surface trap-states.

Air-stable layered bismuth-based perovskite-like materials: Structures and semiconductor properties

Metal halide perovskites are newcomer optoelectronic materials that have attracted enormous attention and single crystal offers better stability and optical electronic performance. In this background, a lead-free, air-stable, effective material of bismuth halide perovskite is highly sought-after. Herein, millimeter-scale single-crystal A3Bi2I9 (A = Cs+ or methylammonium (MA+)) perovskites were synthesized via a facile hydrothermal approach and characterized by various means. Raman spectroscopy results in a layered cleavage distribution. Spin-coating of these compounds produced thin films with uniform surface morphologies, high carrier mobility and superior stabilities. Trivalent-bismuth-based materials were used as the photoactive layer in solution-processed heterojunction solar cell devices, which is a conceptual beneficial exploration and yield power conversion efficiencies of ~ 0.2%.