Perovskite Precursor Solution Research Articles

Phosphonic Chloride Assisted Fabrication of Highly Emissive Mixed Halide Perovskite Films in Ambient Air for Blue Light-Emitting Diodes.

Blue perovskite light-emitting diodes (LEDs) have emerged as promising candidates for full-color display and lighting applications. However, the fabrication of blue-emitting perovskite films typically requires an inert environment, leading to increased complexity and cost in the manufacturing process, which is undesirable for applications of perovskite LEDs. Herein, we report a strategy to fabricate bright blue-emitting perovskite films in ambient air by incorporating phosphonic chlorides in a perovskite precursor solution. We used two different phosphonic chlorides, diphenylphosphonic chloride (DPPC) and phenylphosphonic dichloride (PPDC), and comparatively studied their effects on the properties of perovskite films and the blue LEDs. It is found that PPDC possesses a stronger chlorination ability due to higher hydrolysis reactivity; meanwhile, it has a stronger interaction with the perovskite compared to DPPC, resulting in an improved film quality and enhanced blue emission with a photoluminescence quantum yield of 45%, which represents the record value for the air-processed blue perovskite films. Blue perovskite LEDs are fabricated, and the emission wavelengths are effectively tuned by controlling the concentration of phosphonic chlorides. Benefiting from the optimized perovskite films with reduced nonradiative recombination and promoted charge injection and transport, the PPDC-derived blue perovskite LEDs exhibit improved performance with an external quantum efficiency of 3.3% and 1.2% for the 490 and 480 nm emission wavelength, respectively.

Implementation of a Multi-Functional-Group Strategy for Enhanced Performance of Perovskite Solar Cells through the Incorporation of 3-Amino-4-Phenylbutyric Acid Hydrochloride.

Reducing the defect density of perovskite films during the crystallization process is critical in preparing high-performance perovskite solar cells (PSCs). Here, a multi-functional molecule, 3-phenyl-4-aminobutyric acid hydrochloride (APH), with three functional groups including a benzene ring, ─NH3 + and ─COOH, is added into the perovskite precursor solution to improve perovskite crystallization and device performance. The benzene ring increases the hydrophobicity of perovskites, while ─NH3 + and ─COOH passivate defects related to I- and Pb2+, respectively. Consequently, the power conversion efficiency (PCE) of the optimal device increased to 24.65%. Additionally, an effective area of 1 cm2 with a PCE of 22.45% is also prepared using APH as an additive. Furthermore, PSCs prepared with APH exhibit excellent stability by 87% initial PCE without encapsulation after exposure at room temperature under 25% humidity for 5000 h and retaining 70% of initial PCE after aging at 85°C in an N2 environment for 864 h.

Tin Oxide/Amphiphilic Polymer Double‐Layered Hole Transporter for High‐Efficiency Tin Perovskite Solar Modules

AbstractAn exquisite, engineering of two poor hole transporting materials (HTMs, SnO, and PDTON) to form an excellent double‐layered HTL (SnO/PDTON) for inverted tin‐perovskite solar modules (TPSMs) is developed. SnO/PDTON has better photovoltaic performance than the commonly used PEDOT:PSS HTM when large‐area TPSMs are fabricated. Thermally evaporated SnO (that is a simple, available oxide with high hole mobility, good transparency, and adjustable frontier orbitals energy levels) film is used as a main hole transporting layer (HTL). Amphiphilic polymer PDTON (having the amine and ether groups on the side chains) film is used as a Co‐HTL, cross‐linker, passivator, and interface modification agent, as unveiled various physicochemical studies. Double‐layered SnO/PDTON with a flat morphology and good affinity toward perovskite precursor solution creates also a proper surface for depositing large‐area, high‐quality TPsk film. Therefore, TPSM (25.2 cm2 active area on 10 cm × 10 cm ITO substrate) based on double‐layered SnO/PDTON HTL achieving an efficiency over 10% with a negligible current hysteresis is reported for the first time. This study emphasizes not only the exquisite design of combining the specific characteristics of two prosaic HTMs to become a good double‐layered HTL but also gives a direction toward fabricating TPSMs to be applied in all‐perovskite tandem solar module.

Influence of Donor Skeleton on Intramolecular Electron Transfer Amount for Efficient Perovskite Solar Cells

Influence of Donor Skeleton on Intramolecular Electron Transfer Amount for Efficient Perovskite Solar Cells

Influence of Donor Skeleton on Intramolecular Electron Transfer Amount for Efficient Perovskite Solar Cells.

The passivation of the defects derived from rapid-crystallization with electron-donating molecules is always a prerequisite to obtain desirable perovskite films for efficient and stable solar cells, thus, the in-depth understanding on the correlations between molecular structure and passivation capacity is of great importance for screening passivators. Here, we introduce the double-ended amide molecule into perovskite precursor solution to modulate crystallization process and passivate defects. By regulating the intermediate bridging skeletons with alkyl, alkenyl and benzene groups, the results show the passivation strength highly depends on the spin-state electronic structure that serves as an intrinsic descriptor to determine the intramolecular charge distribution by controlling orbital electron transfer from the donor segment to acceptor segment. Upon careful optimization, the benzene-bridged amide molecule demonstrates superior efficacy on improving perovskite film quality. As a physical proof-of-concept, the carbon-based, all-inorganic CsPbI2Br solar cell delivers a significantly increased efficiency of 15.51% with a remarkably improved stability. Based on the same principle, a champion efficiency of 24.20% is further obtained on the inverted (Cs0.05MA0.05FA0.9)Pb(I0.93Br0.07)3 solar cell. These findings provide new fundamental insights into the influence of spin-state modulation on effective perovskite solar cells.

Improving Hybrid Tin Halide Films by Tin Trifluoromethanesulfonate for Lead-Free Perovskite Solar Cells.

Tin-based perovskite solar cells (Sn-PSCs) without toxic lead ions outperform other types of lead-free PSCs in terms of photovoltaic performance. To avoid the oxidation of Sn2+ cations and the formation of vacancy defects, most reports involve the addition of SnF2 to the perovskite precursor solution, but hybrid tin halide (Sn-PVK) films still suffer from poor crystallinity and stability. In this work, we used an alternative additive of tin trifluoromethanesulfonate (Sn(OTF)2). Compared to SnF2, the solubility of Sn(OTF)2 in the precursor solution is greatly improved, and the crystal nucleation process is delayed, resulting in the enhancement of crystal growth. The coordination ability of the OTF- anions suppresses the oxidation of Sn2+ cations, which promotes the stability of Sn-PVK films. By replacing the conventional additive of SnF2 with Sn(OTF)2, the device achieves an increase in power conversion efficiency from 7.96% to 10.3%, while the stability of the devices is improved simultaneously.

A Synergistic Effect among Multiple Functional Groups of 4‐PyAO Additive for Performance Enhancement of Tin‐Based Perovskite Solar Cells

Tin‐based perovskite is a competitive analog with lead halide perovskite, but there are significant gaps in power conversion efficiency (PCE) and stability between tin‐ and lead‐based perovskite solar cells. The characteristics of the easy oxidizability of Sn2+ and the rapid crystal growth for tin‐based perovskite are two major issues remained to be overcome. Herein, an additive (4‐pyridylamidoxime (4‐PyAO)) with multiple functional groups is introduced in the perovskite precursor solution. The oxidation of Sn2+ and the crystallization rate of perovskite are both retarded by 4‐PyAO addition. The prepared perovskite film is of high quality with fewer trap states and carrier recombination, and carrier extraction and transfer between the perovskite film and the adjacent carrier transport layer also become more efficient. As a result, the corresponding devices deliver the highest PCE of 9.02%, accompanied by short‐circuit current density, open‐circuit voltage, and fill factor of 19.90 mA cm−2, 0.63 V, and 72.48%, respectively. More importantly, the best device without encapsulation maintains 92% of its initial PCE after 2500 h aging test in nitrogen atmosphere, which may be attributed to a synergic effect among the different functional groups.

Perovskite/La-BDC heterojunction enhances the performance of carbon-based perovskite solar cells

Carbon-based Perovskite Solar Cells (C-PSCs) present a promising avenue for enhancing the stability and commercialization of PSCs. However, the power conversion efficiency (PCE) of C-PSCs still lags behind that of metal-based PSCs. In this study, La-BDC (La-MOF prepared by La3+ and ligand H2BDC) has successfully synthesized using a simple hydrothermal method and then directly introduced into CH3NH3PbI3 (MAPbI3) perovskite precursor solution to prepare perovskite/La-BDC heterojunction structure with remarkable properties in light absorption, hydrophobicity, and crystallinity. By incorporating this structure, the PCE of C-PSCs with an FTO/SnO2/MAPbI3/La-BDC/Carbon architecture was effectively enhanced. The presence of CO functional group in La-BDC effectively reduced interface defects while improving carrier separation efficiency, and successfully passivated the free Pb2+ ions within the perovskite. Remarkably, the La-BDC-based device achieved a superior PCE of 14.95%, surpassing the pristine device's PCE by an impressive margin of 20.37%. Moreover, even after a 31 days period of air storage (temperature range of 15–25℃, humidity range of 15–30%), the La-BDC-based devices maintained over 90% of the initial performance, demonstrating excellent stability. This study provides a facile and effective strategy for improving the PCE and stability of C-PSCs through implementing a La-BDC heterojunction structure， and provides a new idea for MOF materials in the field of PSCs.

Synchronous effect of coordination and hydrogen bonds boosting the photovoltaic performance of perovskite solar cells

Superior quality of perovskite film with perfect crystalline and low defect density is crucial for achieving excellent photovoltaic performance and durability of perovskite solar cells (PSCs), and regulation of growth of perovskite crystal and defects passivation by additive is remain challenge. Herein, two acyl molecules (Succinimide: SCI, and Hydantoin: HDT) were incorporated into perovskite precursor solution as additive. It can be found that the HDT molecule can not only passivate undercoordinated Pb2+ defects in perovskite films by the -C=O groups with coordination bonds, but also formed hydrogen bonds with I− by -NH- group, which effectively inhibited the formation of iodine vacancy defects and regulated growth rate of perovskite crystals, and the quality of perovskite films was optimized with enlarging grain size and reduced trap-density. Consequently, power conversion efficiency of HDT-based device was enhanced from 19.47 % to 21.00 %, with an enhancement of JSC and VOC. Moreover, the HDT-based device without encapsulation retained 83.7 % of its initial PCE after being aged at 10–20 % RH for 60 days. Obviously, such a study could provide a new strategy to optimize quality of perovskite film for boosting performance of PSCs.

Accelerated formation of photoactive formamidinium-based lead triiodide perovskite crystals by the addition of copper iodide

Additions of copper iodide (CuI), rubidium iodide, or cesium iodide to perovskite precursor solutions accelerated the formation of the photoactive α-phase of formamidinium lead triiodide (FAPbI3) perovskite crystals. In particular, the addition of CuI suppresses the formation of low-dimensional perovskite phases, thereby reducing carrier transport. The first-principles calculations revealed that substituting Cu at the formamidinium site could maintain the effective mass ratios of the α-phase. The CuI addition to FAPbI3 is expected to enhance its photovoltaic properties. Moreover, introducing CuI into perovskite precursor solutions is suggested as a new approach to accelerate the formation of the photoactive α-FAPbI3 phase.

Bi‐Functional Chelating Ligand Enables Ultra‐Stable Blue Emissive CsPbBr3 Nanoplatelets Film

AbstractQuantum‐confined perovskite CsPbBr3 Nanoplatelets (NPLs) have recently emerged as promising blue‐emitting materials for perovskite light‐emitting diodes (PeLEDs). Yet, their susceptibility to optical instability in solid films under ambient conditions poses a significant hindrance. This study introduces a novel chelating strategy that utilizes metal manganese ions and multidentate ligands, markedly improving the structural stability, and emission efficiency of NPLs. The approach involves adding Diethylenetriaminepentaacetic acid (DTPA) to the perovskite precursor solution, which allows for strong coordination to surface [PbBr6]4− octahedrons via its multiple chelation sites. Ensuing metal manganese ion integration during the purification phase addresses Pb2+ and Br− site vacancies, culminating in near‐perfect octahedral structures with significantly fewer vacancies. These metal manganese ions are then further immobilized on the NPLs surface by the chelating effect of unbound DTPA functional groups. The resultant CsPbBr3 NPLs films demonstrate an impressive PLQY of 66%, showcasing remarkable air stability with consistent blue emission for up to 5 days. The CsPbBr3 NPLs‐based PeLEDs show electroluminescence at 460 nm with a current efficiency of 1.07 cd A−1 and a maximum luminance of 220 cd m−2. The proposed chelating strategy positions perovskite NPLs as an extremely promising prospect in future applications of high‐definition displays and high‐quality lighting.

Spiro-Bifluorene-Cored Dopant-Free Conjugated Polymeric Hole-Transporting Materials Containing Passivation Parts for Inverted Perovskite Solar Cells.

Two spiro-bifluorene-based dopant-free HTMs (X22 and X23) have been synthesized by facilely condensing spiro-bifluorene diamine with 3,4-ethylenedioxythiophene (EDOT)-5,7-dicarbonyl dichloride and 2,3,5,6-tetrafluoro-terephthaloyl dichloride, respectively. In the X22 molecule, lone pairs of electrons on the sulfur (S) and oxygen (O) functional groups interact with the perovskite materials. The hole mobility (μh) of X22 (3.9 × 10-4 cm2 V-1 S1-) is more than twice that of X23 (1.4 × 10-4 cm2 V-1 S1-). The conductivity (σ0) of X22 is 2.73 × 10-4 S cm-1, which is also higher than that of X23 (2.39 × 10-4 S cm-1). The EDOT moiety benefits the contact angle of CH3NH3PbI3 precursor solutions on HTMs as low as 24°. The X22-based device with an indium-doped tin oxide/hole transport material (HTM)/CH3NH3PbI3/phenyl-C61-butyric acid methyl ester (PC61BM)/bathocuproine/Ag structure achieves a power conversion efficiency (PCE) of 19.18%. The PCE of the device based on X23 containing fluorine is 18.70%, and the contact angle between HTM and the perovskite precursor solution is 32°. The X22- and X23-based devices at ambient temperature (≈25 °C) in N2 retain 86% and 79% of the initial PCE after 150 days. The effect of S, O, and F heteroatoms plays an important role in the side chain modification of HTMs, improving defect passivation in HTM/CH3NH3PbI3 interfaces by multiple functional groups.

Enhancing Efficiency of Large-Area Wide-Bandgap Perovskite Solar Modules with Spontaneously Formed Self-Assembled Monolayer Interfaces.

Wide-bandgap (WBG) perovskites play a crucial role in perovskite-based tandem cells. Despite recent advances using self-assembled monolayers (SAMs) to facilitate efficiency breakthroughs, achieving precise control over the deposition of such ultrathin layers remains a significant challenge for large-scale fabrication of WBG perovskite and, consequently, for the tandem modules. To address these challenges, we propose a facile method that integrates MeO-2PACz and Me-4PACz in optimal proportions (Mixed SAMs) into the perovskite precursor solution, enabling the simultaneous codeposition of WBG perovskite and SAMs. This technique promotes the spontaneous formation of charge-selective contacts while reducing defect densities by coordinating phosphonic acid groups with the unbonded Pb2+ ions at the bottom interface. The resulting WBG perovskite solar cells (PSCs) demonstrated a power conversion efficiency of 19.31% for small-area devices (0.0585 cm2) and 17.63% for large-area modules (19.34 cm2), highlighting the potential of this codeposition strategy for fabricating high-performance, large-area WBG PSCs with enhanced reproducibility. These findings offer valuable insights for advancing WBG PSCs and the scalable fabrication of modules.

In Situ Synthesized Low-Dimensional Perovskite for >25% Efficiency Stable MA-Free Perovskite Solar Cells.

Developing an additive to effectively regulate the perovskite crystallization kinetics for the optimized optoelectronic properties of perovskite film plays a vital role in obtaining high efficiency and stable perovskite solar cells (PSCs). Herein, a new additive is designed and directly synthesized in perovskite precursor solution by utilizing an addition reaction between but-3-yn-1-amine hydrochloride (BAH) and formamidinium iodide. It is found that its product may control the intermediate precursor phase for regulating perovskite nucleation, leading to advantageous 2D perovskite to induce growth of perovskite along the preferred [001] orientation with not only released lattice strain but also strong interaction with perovskite to passivate its surface defects. By taking advantage of the above synergistic effects, the optimized PSC delivers an efficiency of 25.19% and a high open-circuit voltage (VOC) of 1.22 V. Additionally, the devices demonstrate good stability, remaining over 90% of their initial efficiencies under ambient atmosphere conditions for 60 days, high temperature of 85°C for 200 h, or maximum power point tracking for 500 h.

Efficient Tin-Lead Perovskite Solar Cells with a Ultrawide Usage Windows of Precursor Solution Opened by SnF2.

High quality tin-lead perovskite solar cells (Sn─Pb PSCs) can be fabricated via simple solution processing methods. However, the instability of precursor solutions and their narrow usage windows still pose challenges in manufacturing efficient and reproducible Sn─Pb PSCs, hindering the commercialization of PSCs. Fluorine tin (SnF2 ) is widely used as an antioxidant to improve the crystallinity of perovskite. In this study, another role of SnF2 as a stabilizer is found to restrain the deprotonation of methylammonium iodide (MAI)in the precursor solution, which improves their stability and expands their usage windows. Due to the inhibition of SnF2 on oxidation and deprotonation, stable large-sized colloidal clusters form gradually in perovskite precursor solution during aging, leading to uniform nucleation/crystallization during film growth, significantly reducing the roughness and defect density in the films. Because of the competitive deprotonation and oxidation process of Sn2+ , the benefit of larger cluster maximizes after about ten days storage of precursor solution. The champion efficiency of Sn─Pb PSCs prepared with 10days aged precursor solution is 22.00%. High performance of devices fabricated with precursor solution stored for even ≈40days discloses the wide usage windows of precursor solution with SnF2 additive.

Co-solvent strategy for highly efficient perovskite solar cells by spray coating

The ultrasonic spray coating has been shown to be an effective technique for scaling up production. The nucleation and crystallization process of the perovskite film prepared by the ultrasonic spraying approach is more complicated than that by the spin coating, but they are essential to gaining efficient perovskite solar cells (PSCs). At the same time, the green solvent is the primary problem that must be solved in the process of PSCs commercialization. In this paper, the low boiling point and green solvent isopropyl alcohol (IPA) is introduced into the perovskite precursor solution to prepare FAPbI3 perovskite by ultrasonic spraying. The addition of IPA enhanced the saturated vapor pressure of the precursor solution, which can create the local chemical microenvironment on the film surface and subsequently retard the nucleation rate from 8.31 s to 8.54 s at nucleation stage. The local chemical improves the initial homogeneity of the sol–gel phase and then leads to improved structural and optoelectronic properties within the FAPbI3 film via sufficient crystallization from the sol–gel phase to α-FAPbI3. Ultimately, IPA-based PSCs exhibit the champion device efficiency of 22.43 %. The good long-term stability of PSCs (maintain more than 90 % of the initial efficiency after 1000 h, and keep 80 % after 400 h) in ambient conditions.

Room Temperature Ionic Liquid Capping Layer for High Efficiency FAPbI3 Perovskite Solar Cells with Long-Term Stability.

Ionic liquid salts (ILs) are generally recognized as additives in perovskite precursor solutions to enhance the efficiency and stability of solar cells. However, the success of ILs incorporation as additives is highly dependent on the precursor formulation and perovskite crystallization process, posing challenges for industrial-scale implementation. In this study, a room-temperature spin-coated IL, n-butylamine acetate (BAAc), is identified as an ideal passivation agent for formamidinium lead iodide (FAPbI3 ) films. Compared with other passivation methods, the room-temperature BAAc capping layer (BAAc RT) demonstrates more uniform and thorough passivation of surface defects inthe FAPbI3 perovskite. Additionally, it provides better energy level alignment for hole extraction. As a result, the champion n-i-p perovskite solar cell with a BAAc capping layer exhibits a power conversion efficiency (PCE) of 24.76%, with an open-circuit voltage (Voc) of 1.19V, and a Voc loss of ≈330mV. The PCE of the perovskite mini-module with BAAc RT reaches 20.47%, showcasing the effectiveness and viability of this method for manufacturing large-area perovskite solar cells. Moreover, the BAAc passivation layer also improves the long-term stability of unencapsulated FAPbI3 perovskite solar cells, enabling a T80 lifetime of 3500h when stored at 35% relative humidity at room temperature in an air atmosphere.

Dopant-additive synergism enhances perovskite solar modules

Perovskite solar cells (PSCs) are among the most promising photovoltaic technologies owing to their exceptional optoelectronic properties1,2. However, the lower efficiency, poor stability and reproducibility issues of large-area PSCs compared with laboratory-scale PSCs are notable drawbacks that hinder their commercialization3. Here we report a synergistic dopant-additive combination strategy using methylammonium chloride (MACl) as the dopant and a Lewis-basic ionic-liquid additive, 1,3-bis(cyanomethyl)imidazolium chloride ([Bcmim]Cl). This strategy effectively inhibits the degradation of the perovskite precursor solution (PPS), suppresses the aggregation of MACl and results in phase-homogeneous and stable perovskite films with high crystallinity and fewer defects. This approach enabled the fabrication of perovskite solar modules (PSMs) that achieved a certified efficiency of 23.30% and ultimately stabilized at 22.97% over a 27.22-cm2 aperture area, marking the highest certified PSM performance. Furthermore, the PSMs showed long-term operational stability, maintaining 94.66% of the initial efficiency after 1,000 h under continuous one-sun illumination at room temperature. The interaction between [Bcmim]Cl and MACl was extensively studied to unravel the mechanism leading to an enhancement of device properties. Our approach holds substantial promise for bridging the benchtop-to-rooftop gap and advancing the production and commercialization of large-area perovskite photovoltaics.

Gel‐Derived Amorphous Precursor Enables Homogeneous Pure‐Phase α‐FAPbI3 Films for Efficient and Stable Perovskite Solar Cells

AbstractPure‐phase α‐formamidinium lead iodide (α‐FAPbI3) perovskite solar cells (PSCs) possess potential high efficiency because of suitable bandgap. However, achieving high‐quality α‐FAPbI3 films during the spin‐coating process is challenging without anti‐solvent extraction, due to the spontaneous formation of the more stable δ‐FAPbI3 phase and the complexity of multi‐component perovskite precursor solutions. Here a gel precursor with an amorphous structure to eliminate the need for anti‐solvent extraction in achieving the homogeneous and highly oriented pure‐phase α‐FAPbI3 is devised films. The incorporation of N,N′‐dimethylpropyleneurea, and alkylammonium chloride results in extended iodoplumbate clusters in the perovskite precursor solution. In situ, spectroscopic analysis reveals that the emergence of the stable amorphous gel precursor during the initial solidification stage ensures a uniform solute distribution. This effectively prevents preferentially oriented growth in the crystal phase precursor, leading to a significant enhancement in film homogeneity. As a result, power conversion efficiencies of 24.17% for the PSC, and 19.3% for the module are achieved, along with superior operational stability, retaining 96.1% of their initial efficiency after 850 h at the maximum power point tracking. These demonstrate the best performance for the reported pure‐phase α‐FAPbI3 PSCs without anti‐solvent extraction, showing great promise for scalable manufacture.

Efficient Sn–Pb Mixed Perovskite Solar Cells Via Minimizing Solvent Oxidation

AbstractTin (Sn)–lead (Pb) mixed perovskite solar cells (PSCs) stand out as the optimal choice for the bottom subcell of the all‐perovskite tandem solar cells. One of the major challenges impeding the further enhancement of Sn–Pb mixed PSCs power conversion efficiency (PCE) is the easy oxidation of Sn2+ to Sn4+ and a large number of Sn vacancies in the perovskite films. In this work, the sources of Sn2+ oxidation in the perovskite precursor solution are systematically investigated, focusing on the oxidation state of raw materials, solvent‐dissolved oxygen, and solvent oxidizing ability. It is discovered that compared to the commonly used dimethyl sulfoxide (DMSO) solvent, N, N'‐Dimethylpropyleneurea (DMPU) exhibits a weaker oxidizing ability while forming excellent coordination with the perovskite precursor. Using a mixed solvent of N, N‐Dimethylformamide (DMF), and DMPU as the precursor solvent not only obviates the need for additional antioxidants but also demonstrates reduced oxidation susceptibility toward Sn–Pb mixed perovskite. Utilizing a gas‐assisted technique without anti‐solvents, high‐efficiency Sn–Pb mixed PSCs are fabricated. These findings not only deepen the understanding of the oxidation phenomena in Sn–Pb perovskite precursor solutions but also provide essential guidance for the scalable production of Sn–Pb mixed PSCs and tandem solar cells.