N-butylammonium Iodide Research Articles

Enhancing the Efficiency and Stability of Perovskite Solar Cells Using Chemical Bath Deposition of SnO2 Electron Transport Layers and 3D/2D Heterojunctions.

Chemical bath deposition (CBD) is an effective technique used to produce high-quality SnO2 electron transport layers (ETLs) employed in perovskite solar cells (PSCs). By optimizing the CBD process, high-quality SnO2 films are obtained with minimal oxygen vacancies and close energy level alignment with the perovskite layer. In addition, the 3D perovskite layers are passivated with n-butylammonium iodide (BAI), iso-pentylammonium iodide (PNAI), or 2-methoxyethylammonium iodide (MOAI) to form 3D/2D heterojunctions, resulting in defect passivation, suppressing ion migration and improving charge carrier extraction. As a result of these heterojunctions, the power conversion efficiency (PCE) of the PSCs increased from 21.39% for the reference device to 23.70% for the device containing the MOAI-passivated film. The 2D perovskite layer also provides a hydrophobic barrier, thus enhancing stability to humidity. Notably, the PNAI-based device exhibited remarkable stability, retaining approximately 95% of its initial efficiency after undergoing 1000-h testing in an N2 environment at room temperature.

Modulating Dimensionality of 2D Perovskite Layers for Efficient and Stable 2D/3D Perovskite Photodetectors.

Two-dimensional (2D) perovskites have been widely adopted for improving the performance and stability of three-dimensional (3D) metal halide perovskite devices. However, rational manipulation of the phase composition of 2D perovskites for suitable energy level alignment in 2D/3D perovskite photodetectors (PDs) has been rarely explored. Herein, we precisely controlled the dimensionality of the 2D perovskite on CsPbI2Br films by tuning the polarity of the n-butylammonium iodide (BAI)-based solvents. In comparison to the pure n = 1 2D perovskite (ACN-BAI) formed by acetonitrile treatment, a mixture of n = 1 and n = 2 phases (IPA-BAI) generated by isopropanol (IPA) treatment guaranteed more robust defect passivation and favorable energy level alignment at the perovskite/hole transport layer interface. Consequently, the IPA-BAI PD exhibited a responsivity of 0.41 A W-1, a detectivity of 1.01 × 1013 Jones, and a linear dynamic range of 120 dB. Furthermore, the mixed-phase 2D layer effectively shielded the 3D perovskite from moisture. The IPA-BAI device retained 76% of its initial responsivity after 500 h of nonencapsulated storage at 10% relative humidity. This research provides valuable insights into the dimensional modulation of 2D perovskites for further enhancing the performance of 2D/3D perovskite PDs.

Surface Reconstruction for Efficient and Stable Monolithic Perovskite/Silicon Tandem Solar Cells with Greatly Suppressed Residual Strain.

Despite the swift rise in power conversion efficiency (PCE) to more than 32%, the instability of perovskite/silicon tandem solar cells is still one of the key obstacles to practical application and is closely related to the residual strain of perovskite films. Herein, a simple surface reconstruction strategy is developed to achieve a global incorporation of butylammonium cations at both surface and bulk grain boundaries by post-treating perovskite films with a mixture of N, N-dimethylformamide and n-butylammonium iodide in isopropanol solvent, enabling strain-free perovskite films with simultaneously reduced defect density, suppressed ion migration and improved energy level alignment. As a result, the corresponding single-junction perovskite solar cells yield a champion PCE of 21.8%, while maintaining 100% and 81% of their initial PCEs without encapsulation after storage for over 2500h in N2 and 1800h in air, respectively. Remarkably, we further demonstrate a certified stabilized PCE of 29.0% for the monolithic perovskite/silicon tandems based on tunnel oxide passivated contacts. The unencapsulated tandem device retains 86.6% of its initial performance after 306 hours at maximum power point (MPP) tracking under continuous xenon-lamp illumination without filtering ultraviolet (in air, 20-35 °C, 25-75%RH, most often ∼60%RH). This article is protected by copyright. All rights reserved.

Stable high conversion efficiency of Quasi-2D perovskite solar cells via potassium iodide as additive

Although two-dimensional (2D) perovskite is more stable than three-dimensional (3D) perovskite, its poor film quality and low photoelectric conversion efficiency are still the focuses of researchers. In this article, we introduce a simple and effective method to modify the quasi-2D (BA)2(MA)3Pb4I13 perovskite solar cells by introducing potassium iodide as an additive. We found that the introducing K ion made perovskite film more compact, reduced the number of grain boundaries and regulated the band alignment. Besides, the incorporation of K+ reduced the nonradiative recombination and hysteresis effect of the device. As a result, the power conversion efficiency (PCE) of solar cells increased from initial 13.91% to 16.82% under optimized concentration of 16% (mole ratio compared to N-butyl ammonium iodide BAI). What is more, the device with K+ modification showed excellent environmental stability, which could maintain 95% of their original efficiency after 720 h under ambient air condition, whereas the pristine devices without K+ only keep 53% of their initial efficiency and the thermal stability has also been improved. This result provides a simple and promising method through additive engineering to achieve high PCE and stable quasi-2D perovskite solar cells.

Manipulating the Formation of 2D/3D Heterostructure in Stable High-Performance Printable CsPbI3 Perovskite Solar Cells.

Manipulating the formation process of the 2D/3D perovskite heterostructure, including its nucleation/growth dynamics and phase transition pathway, plays a critical role in controlling the charge transport between 2D and 3D crystals, and consequently, the scalable fabrication of efficient and stable perovskite solar cells. Herein, the structural evolution and phase transition pathways of the ligand-dependent 2D perovskite atop the 3D surface are revealed using time-resolved X-ray scattering. The results show that the ligand size and shape have a critical influence on the final 2D structure. In particular, ligands with smaller sizes and more reactive sites tend to form the n= 1 phase. Increasing the ligand size and decreasing the reactive sites promote the transformation from 3D to n= 3 and n< 3 phases. These findings are useful for the rational design of the phase distribution in 2D perovskites to balance the charge transport and stability of the perovskite films. Finally, solar cells based on ambient-printed CsPbI3 with n-butylammonium iodide treatment achieve an improved efficiency of 20.33%, which is the highest reported value for printed inorganic perovskite solar cells.

Additive Engineering of the CuSCN Hole Transport Layer for High-Performance Perovskite Semitransparent Solar Cells.

CuSCN has been widely considered a promising candidate for low-cost and high-stable hole transport material in perovskite semitransparent solar cells (STSCs). However, the low conductivity of the solution-processed CuSCN hole transport layer (HTL) hinders the hole extraction and transport in devices, which makes it hard to achieve devices with high performance. Herein, we report a facile additive engineering approach to optimize the p conductivity of CuSCN HTLs in perovskite STSCs. The n-butylammonium iodide additive facilitates the formation of Cu2+ and generates more Cu vacancies in the CuSCN HTL. This realizes a significant enhancement of the hole concentration and p conductivity of the film. Moreover, the additive improves the solubility of the CuSCN precursor solution and results in a uniform coverage on the perovskite active layer. Therefore, the perovskite STSC with a high power conversion efficiency (PCE) of 19.24% has been achieved, which is higher than that of the spiro-OMeTAD (18.83%) and CuSCN (17.45%) counterparts. In addition, the unencapsulated CuSCN-based device retains 87.5% of the initial PCE after 20 days in the ambient atmosphere.

Improved Performance of CH3NH3PbI3-xClx Resistive Switching Memory by Assembling 2D/3D Perovskite Heterostructures.

The rapidly growing demand for fast information storage and processing has driven the development of resistive random access memories (RRAMs). Recently, RRAMs based on organometal halide perovskite materials have been reported to have promising memory properties, which are essential for next-generation memory devices. In this study, a hybrid two-dimensional/three-dimensional (2D/3D) perovskite heterostructure has been created by depositing n-butylammonium iodide on top of the CH3NH3PbI3-xClx (MAPbI3-xClx) surface. The perovskite film is fabricated by a facile one-step spin-coating method with room-temperature molten salt methylammonium acetate in the air. Resistive switching memory devices with a 2D/3D perovskite heterostructure exhibit a significantly improved switching window (ON/OFF ratio over 103) with a lower operation voltage compared with their 3D counterparts. The 2D/3D perovskite heterostructure is advantageous for fabricating uniform-crystalline-grain, highly compact structures and can passivate defect states for the MAPbI3-xClx film and the interface, which results in improved memory properties. These results provide a new perspective for developing high-performance perovskite-based memory devices.

Structural changes and band gap tunability with incorporation of n-butylammonium iodide in perovskite thin film

The current work presents structural change and band gap tunability using hybrid organic-inorganic perovskite with the incorporation of long chain ammonium halide. Thin films of MAPbI3 with different ratio of n-butylammonium iodide (BAI) have been successfully deposited on the substrate using a single step coating technique. X-ray diffraction scans revealed the transition of the 3D structure of MAPbI3 to quasi-2D perovskite structure when BAI loading increase with a crystallite size range approximately 16 nm. This structural changeis reflected in the band gap as it increased from 1.59 eV for bulk crystal MAPbI3 to 2.13 eV for BAI and MAPbI3 ratio of 1:1. Correspondingly, photoluminescence measurement showed a blue shift in perovskite emission due to the transition of 3D to 2D layered structure perovskite. Raman spectra confirm that all fabricated films are of pristine quality and no corresponding degradation peaks of PbI2 is observed. These characteristics are important to address the single step deposition method of hybrid perovskite for perovskite solar cells application.

3-Bromo-1,1,1-trifluoro-2-propanol assisted chemical fixation of CO2 and epoxides

3-Bromo-1,1,1-trifluoro-2-propanol (3-BTFP) in combination with n-butylammonium iodide (TBAI) was proved to be an efficient organocatalyst for chemical fixation of CO2 with various epoxides to the respective cyclic carbonates. A possible reaction mechanism was proposed wherein 3-BTFP activated epoxide through hydrogen bonding interaction. This mechanism is revealed by the results of FT-IR spectra and 1H NMR titration, and the synergetic effect functioned by 3-BTFP and TBAI ensures the reaction proceeding effectively. Herein, 3-BTFP represents a commercially available, stable and metal-free hydrogen-bonding donor for CO2 transformation, which has a potential application for the large-scale synthesis of cyclic carbonates.

Unveiling the guest effect of N-butylammonium iodide towards efficient and stable 2D-3D perovskite solar cells through sequential deposition process

Improving the stability of hybrid organic-inorganic halide perovskite materials is urgent and essential for their applications in optoelectronic devices. Here, we introduce n-butylammonium iodide (BAI) into lead-iodide crystals as guest molecules. As a result of guest effect, only a small amount BA2PbI4 two-dimensional (2D) perovskite (n = 1) is formed in PbI2-BAI films. Most of BAI crystals efficiently cut and squeeze the lattice network of lead iodide. The better orientation of 2D lead iodide crystals is obtained via this guest effect. In the following sequential deposition process, that BAI re-dissolve in MAI isopropanol (IPA) solution leads to a mesoporous structure of PbI2 and introduces a 2D perovskite (n = 2) protect layer in 3D MAPbI3 after annealing. Finally, the morphology, crystallization and stability of CH3NH3PbI3 are simultaneously improved by the insertion of BAI guest molecules. Consequently, CH3NH3PbI3 PSCs with an optimized cutting behavior exhibited a power conversion efficiency of 18% and significantly improved the stability.

Highly efficient and stable 2D–3D perovskite solar cells fabricated by interfacial modification

Two-dimensional (2D) perovskites, which have excellent stability compared with three-dimensional (3D) perovskites owing to the effective protection of the hydrophobic organic ligands, have become a research hotspot and have made great developmental progress in recent years. Herein, an n-butylammonium iodide (BAI) post-treatment process was developed to fabricate a 2D–3D hybrid perovskite with a thin layer of 2D perovskite covered on the surface of the 3D CH3NH3PbI3 perovskite. The growth process of 2D perovskite is formed through the chemical reaction between BAI and the residual PbI2, which improves stability and reduces the number of crystal defects of 3D perovskite by optimizing stoichiometry. Compared with the 3D counterpart, the 2D–3D hybrid perovskite shows outstanding light and air stability when exposed to external environments. Moreover, structure conversion from 3D to 2D–3D can induce the passivation of defects in the 3D films. The power conversion efficiency of the 2D–3D solar cell exceeds 18% and retains 80% of the initial value after more than 2000 h of storage without encapsulation.

Enhanced Thermal Stability in Perovskite Solar Cells by Assembling 2D/3D Stacking Structures.

Two-dimensional (2D) perovskites have been shown to be more stable than their three-dimensional (3D) counterparts due to the protection of the organic ligands. Herein a method is introduced to form 2D/3D stacking structures by the reaction of 3D perovskite with n-Butylamine (BA). Different from regular treatment with n-Butylammonium iodide (BAI) where 2D perovskite with various layers form, the reaction of BA with MAPbI3 only produce (BA)2PbI4, which has better protection due to more organic ligands in (BA)2PbI4 than the mixture of 2D perovskites. Compared to BAI treatment, BA treatment results in smoother 2D perovskite layer on 3D perovskites with a better coverage. The photovoltaic devices with 2D/3D stacking structures show much improved stability in comparison to their 3D counterparts when subjected to heat stress tests. Moreover, the conversion of defective surface into 2D layers also induces passivation of the 3D perovskites resulting in an enhanced efficiency.

Synthesis and structural characterization of 3- O-ethylene glycol functionalized cellulose derivatives

The synthesis of 3- O-ethylene glycol cellulosics via 2,6-di- O-thexyldimethylsilyl cellulose was studied. Reaction yield and degree of substitution were dependent on reaction conditions and size of the ethylene glycol group. The presence of tetra- n-butylammonium iodide in catalytic amounts and prolonged reaction times significantly increased the degree of substitution of the ethylene glycol substituents. However, the longer reaction times lead to significant degradation of the cellulosic polymer chain. The structure of the 3- O-ethylene glycol 2,6-di- O-thexyldimethylsilyl cellulose intermediates and the 3- O-ethylene glycol 2,6-di- O-acetyl celluloses were confirmed by means of one- and two-dimensional NMR spectroscopy. The degree of 3- O-ethylene glycol substitution was confirmed by quantitative 13C NMR ratified by T1 experiments.

Ion-pair and triple-ion studies of some tetraalkylammonium halides in pure 1,3-dioxolane at 298.15 K

Conductivities of some tetraalkylammonium halides, viz. tetramethylammonium iodide (Me 4NI), tetraethylammonium bromide (Et 4NBr), tetraethylammonium iodide (Et 4NI), tetra- n-propylammonium bromide (Pr 4NBr), tetra- n-butylammonium bromide (Bu 4NBr), tetra- n-butylammonium iodide (Bu 4NI) and tetra- n-heptylammonium bromide (Hp 4NBr) were measured at 298.15 K in 1,3-dioxolane which has a low permittivity ( ε = 7.13). A minima in the conductometric curves (molar conductance, Λ vs. square root of concentration, √ c) was observed for concentrations which were dependant upon both the salt and the solvent. The observed molar conductivities were explained by the formation of ion-pairs (M + + X − ↔ MX, K P) and triple-ions (2M + + X − ↔ M 2X +; M + + 2X − ↔ MX 2 −, K T). A linear relationship between the triple-ion formation constants [log ( K T/ K P)] and the salt concentrations at the minimum conductivity (log C min) was given for all the salts in 1,3-dioxolane. The formation of triple-ions might be attributed to the ion sizes in solutions in which Coulombic interactions and non-Coulombic interactions act as the main forces between the ions (R 4N +…..X −).

A simple procedure for the esterification of alcohols with sodium carboxylate salts using 1-tosylimidazole (TsIm)

An efficient and selective method for esterification of alcohols using N-( p-toluenesulfonyl)imidazole (TsIm) is described. In this method, alcohols are refluxed with a mixture of RCO 2Na (R: alkyl and aryl), TsIm, and triethylamine in the presence of catalytic amounts of tetra- n-butylammonium iodide (TBAI) in DMF to afford the corresponding esters in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°.

Iodobenzene-catalysed iodolactonisation using sodium perborate monohydrate as oxidant

A convenient approach has been developed for iodolactonisation using iodobenzene as catalyst. The active reagent was generated in situ with tetra- n-butylammonium iodide (TBAI) and hypervalent iodine reagent, diacetoxyiodobenzene (PIDA). PIDA, in turn, was generated in situ using a catalytic amount of iodobenzene with sodium perborate monohydrate as the stoichiometric oxidant. A variety of olefinic acids including δ-pentenoic acids, δ-pentynoic acids and δ-hexynoic acid gave high yields of lactones using this methodology.

Solvation of potassium and tetra- n-butylammonium iodides in methanol from acoustic and positron annihilation measurements

The positron annihilation and acoustic methods were applied to investigate solvation of potassium iodide, and tetra- n-butylammonium iodide in methanol. The acoustic results show that the influence of KI on the structure of liquid is stronger but shorter in their range than that of (C 4H 9) 4NI, although the solvation numbers are lower for KI. The solvation numbers of ions (five for K +, seven for (C 4H 9) 4N + and two for I −) are deduced. The positron annihilation suggests that the effect of KI on liquid methanol structure is stronger but shorter in range, leading to formation of small but more compressed solvates.

A simple one-pot procedure for the direct conversion of alcohols into alkyl nitriles using TsIm

A convenient and efficient one-pot preparation of nitriles from alcohols using N-( p-toluenesulfonyl)imidazole (TsIm) is described. In this method, treatment of alcohols with a mixture of NaCN, TsIm and triethylamine in the presence of catalytic amounts of tetra- n-butylammonium iodide (TBAI) in refluxing DMF furnishes the corresponding alkyl nitriles in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°.

Synthesis of aryltriethoxysilanes via rhodium(I)-catalyzed cross-coupling of aryl electrophiles with triethoxysilane

The general and efficient silylation of aryl halides has been developed utilizing triethoxysilane and a rhodium catalyst. The substrate scope is broad and includes ortho-, meta-, and para-substituted electron-rich and -deficient aryl iodides. In addition, the silylation of aryl bromides and fluoroalkanesulfonates proceeded in the presence of tetra- n-butylammonium iodide.

Kinetics for synthesizing benzyl salicylate via solid–liquid phase-transfer catalysis

The kinetics for synthesizing benzyl salicylate (C 6H 4(OH)COOCH 2C 6H 5, denoted as Ph(OH)COOR) from the carboxylation of benzyl bromide (C 6H 5CH 2Br, RBr) via solid–liquid phase-transfer catalysis (SLPTC) was investigated. The key component to conduct the substitution reaction is the catalytic intermediate generated from solid sodium salicylate (C 6H 4(OH)COONa, denoted as Ph(OH)COONa) reacted with tetraalkylammonium salt. The concentration of catalytic intermediate remained nearly constant after the induction period and increased with the increase of the amount of catalyst employed. The reaction between catalytic intermediate and organic reactant is identified as the controlling step. Factors affecting the formation of the catalytic intermediate include the relative amounts of catalyst, solid reactant, organic reactant, and extra addition of inorganic salts. Different phase-transfer catalysts were employed to compare their catalytic efficiency: tetra- n-butylammonium bromide (Bu 4NBr, TBAB or QBr in general) > tetra- n-butylammonium iodide (TBAI) > tetra- n-butylphosphonium bromide (TBPB) > aliquat 336 > tetra- n-butylammonium hydrogen sulfate (TBAHS) > polyethylene glycol (PEG) 1500. The product yield above 98% was achieved within 1 h at 70 °C by using tetra- n-butylammonium bromide as the catalyst. A kinetic model was developed for the solid–liquid reaction. The overall reaction can be described by pseudo-first-order kinetics with the apparent activation energy in chlorobenzene to be 62.52 kJ mol −1.