Moisture Instability Research Articles

Stable and Lead-Safe Polyphenol-Encapsulated Perovskite Solar Cells.

Lead (Pb) halide perovskite solar cells (PSCs) exhibit impressive power conversion efficiencies close to those of their silicon counterparts. However, they suffer from moisture instability and Pb safety concerns. Previous studies have endeavoured to address these issues independently, yielding minimal advancements. Here, a general nanoencapsulation platform using natural polyphenols is reported for Pb-halide PSCs that simultaneously addresses both challenges. The polyphenol-based encapsulant is solution-processable, inexpensive (≈1.6 USDm-2), and requires only 5min for the entire process, highlighting its potential scalability. The encapsulated devices with a power conversion efficiency of 20.7% retained up to 80% of their peak performance for 2000h and up to 70% for 7000h. Under simulated rainfall conditions, the encapsulant rich in catechol groups captures the Pb ions released from the degraded perovskites via coordination, keeping the Pb levels within the safe drinking water threshold of 15ppb.

Enhancing the stability of Li2NiO2 cathode additive with polyborosiloxane coating for high-energy lithium-ion batteries

Li2NiO2 has garnered considerable interest as a Li-excess cathode additive for high-energy lithium-ion batteries (LIBs), attributed to its high irreversible capacity during the initial cycle and an operating voltage comparable with that of commercial cathode materials. However, its integration into practical applications is limited by its suboptimal cycling performance owing to moisture instability and gas evolution. To surmount these obstacles, we developed a hybrid surface coating strategy employing polyborosiloxane (PBS)—a structural derivative of polydimethylsiloxane (PDMS) synthesized with boric acid (H3BO3)—applied to a Li2NiO2 cathode additive. The bi-functional of the PBS layer enhances moisture resistance and ionic conductivity on the Li2NiO2 surface. A hydrophobic, elastic PDMS matrix offers conformal coverage, forestalling adverse moisture-induced side reactions. The introduction of H3BO3 into the PDMS matrix on the Li2NiO2 surface fosters the formation of Li–B–O bonds, thus augmenting the ionic conductivity of the coating. This innovative approach with the PBS layer significantly diminishes the interfacial resistance and improves the cycling performance of Li2NiO2 while preventing substantial structural degradation. In a full-cell configuration incorporating a PBS-coated Li2NiO2 cathode additive with a LiNi0.8Co0.1Mn0.1O2 cathode and a SiOx/Graphite anode, the enhanced energy density and sustained stable cycling performance exceed 300 cycles. This hybrid layer can aid in producing longer-lasting, more efficient LIBs that can fulfill the requirements for use in high-energy storage solutions.

Ultrahigh-performance indoor perovskite quantum dot photovoltaics via ligand-passivation engineering

The advancement of perovskite photovoltaic (PePV) systems for harnessing indoor light energy has been accelerated by the advent of the Internet of Things (IoT). However, the commercialization of these systems is impeded by moisture instability and restricted carrier lifetimes. Perovskite quantum dots (PQDs) offer viable solutions for increasing stability despite the potential effects of their organic ligands on efficiency. In this study, a ligand passivation strategy was employed in PQD photovoltaics (PQDPVs) to enhance the carrier lifetime. The inclusion of 2-phenyl-4-(1,2,2-triphenylvinyl) quinazoline (2PACz) in the PQD film effectively reduced surface defects and suppressed trap-assisted charge recombination, resulting in a prolonged carrier lifetime. The charge carrier lifetimes in passivated PQDPVs increased by 35 %. Additionally, the matching of the energy level of the PQD changed after 2PACz passivation engineering with that of the 2PACz showed an advantage for hole transport. PQDPVs fabricated using 2PACz-passivated PQDs showed an impressive output power density (Pout) of 123.3 µW/cm2 (power conversion efficiency of 41.1 %) under a fluorescent lamp (0.30 mW/cm2; 1000 lx) owing to improved open-circuit voltage and fill factor. Moreover, the device maintained more than 80 % of its initial efficiency for 500 h in an ambient atmosphere. These findings highlight the potential of PQDPVs to compete with conventional PePVs for application in self-powered optoelectronic devices under dim illumination.

Reversible CsPbBr3 ↔ CsPb2Br5 Transformation via Reverse Micellar Aqueous Solution.

Lead halide perovskites suffer from water and moisture instability due to the highly ionic nature of the crystal structures, though a few groups took advantage of it for chemical transformation via water-assisted strategy. However, direct exposure of the perovskite to bulk water leads to uncontrolled chemical transformation. Here, we report a controlled chemical transformation of CsPbBr3 to CsPb2Br5 triggered by nanoconfined water by placing CsPbBr3 in the nonpolar phase within a reverse micelle. The chemical transformation reaction is probed by using steady-state and time-resolved optical spectroscopy. We observe absorption and photoluminescence in the UV region stemming clearly from the CsPb2Br5 phase upon interaction with the reverse micellar aqueous solution. Transmission electron microscopy and X-ray diffraction measurements further provided the structure and morphology. Our results direct the formation of CsPbBr3-CsPb2Br5 nanocomposite under dry conditions while the chemically transformed CsPb2Br5 phase exists only in moist conditions, which we explain via the CsBr-stripping mechanism.

Massive Parameter Sweep Experiment on Convective Cloud Environment: Changes in Rainfall Characteristics in Moisture–Instability–Shear Space

Massive Parameter Sweep Experiment on Convective Cloud Environment: Changes in Rainfall Characteristics in Moisture–Instability–Shear Space

Degradation Evolution for Li2 ZrCl6 Electrolytes in Humid Air and Enhanced Air Stability via Effective Indium Substitution.

Superionic halides have aroused interests in field of solid electrolytes such as Li2 ZrCl6 . However, they are still facing challenges including poor air stability which lacks in-depth investigation. Here, moisture instability of Li2 ZrCl6 is demonstrated and decomposition mechanism in air is clearly revealed. Li2 ZrCl6 decomposes into Li2 ZrO3 , ZrOCl2 ·xH2 O and LiCl during initial stage as halides upon moisture exposure. Later, these side products evolve into LiCl(H2 O) and Li6 Zr2 O7 after longer time exposure. More importantly, structure of destroyed halides cannot be recovered after postheating. Later, Indium is doped into Li2 ZrCl6 (9.7 × 10-5 S cm-1 ) to explore its effect on structure and properties. Crystal structure of ball-milled In-doped Li2 ZrCl6 electrolytes is converted from the Li3 YCl6 -like to Li3 InCl6 -likewith increasing In content and ionic conductivity can also be enhanced (0.768-1.13) × 10-3 S cm-1 ). More importantly, good air stability of optimal Li2.8 Zr0.2 In0.8 Cl6 is achieved since halide hydrates are formed after air exposure instead of total decomposition and the hydrates can be restored to Li2.8 Zr0.2 In0.8 Cl6 after postheating. Moreover, reheated Li2.8 Zr0.2 In0.8 Cl6 after air exposure is successfully applied in solid-state LiNi0.8 Co0.1 Mn0.1 O2 /halides/Li6 PS5 Cl/Li-In battery. The results in this work can provide insights into air instability of Li2 ZrCl6 and effective strategy to regulate air stability of halides.

A Customized Hydrophobic Porous Shell for MOF-5.

The susceptibility to moisture of metal-organic frameworks (MOFs) is a critical bottleneck for their wider practical application. Constructing core-shell composites has been postulated as an effective strategy for enhancing moisture resistance, but for fragile MOFs this has rarely been accomplished. We report herein, for the first time, the construction of a customized hydrophobic porous shell, NTU-COF, on the particularly fragile MOF-5 by a "Plug-Socket Anchoring" strategy. Notably, the pore structure of MOF-5 was well maintained, and it could still achieve complete CO2/N2 separation under humid conditions. The homogeneous interface between MOF-5 and NTU-COF has been inspected at atomic resolution by a combination of cryogenic focused ion beam (cryo-FIB) and ultralow-dose (scanning) transmission electron microscope giving profound insight into the mechanism of assembly of the core-shell structure. This work presents a facile strategy for the fabrication of a hydrophobic porous shell for labile MOFs, and provides a general approach for solving the problem of moisture instability of porous materials for practical applications.

Bismuth-Based Halide Perovskites for Photocatalytic H2 Evolution Application.

Metal halide perovskites (MHPs), in particular lead-based perovskites, have earned recognized fame in several fields for their outstanding optoelectronic properties, including direct generation of free charge carriers, optimal ambipolar charge carrier transport properties, high absorption coefficient, point-defect tolerance, and compositional versatility. Nowadays, this class of materials represents a real and promising alternative to silicon for photovoltaic technologies. This worthy success led to a growing interest in the exploration of MHPs in other hot research fields, such as solar-driven photocatalytic water splitting towards hydrogen production. Nevertheless, many of these perovskites show air and moisture instability problems that considerably hinder their practical application for photocatalytic water splitting. Moreover, if chemical instability is a problem that can be in part mitigated by the optimization of the chemical composition and crystal structure, the presence of lead represents a real problem for the practical application of MHPs in commercial devices due to environmental and healthcare issues. To successfully overcome these problems, lead-free metal halide perovskites (LFMHPs) have gained increasing interest thanks to their optoelectronic properties, comparable to lead-based materials, and their more eco-friendly nature. Among all the lead-free perovskite alternatives, this mini-review considers bismuth-based perovskites and perovskite derivatives with a specific focus on solar-driven photocatalysis application for H2 evolution. Special attention is dedicated to the structure and composition of the different materials and to the advantage of heterojunction engineering and the relative impact on the photocatalytic process.

Sn‐O Dual‐Substituted Chlorine‐Rich Argyrodite Electrolyte with Enhanced Moisture and Electrochemical Stability

AbstractChlorine‐rich argyrodite sulfides are one of the most promising solid electrolytes for all‐solid‐state batteries owing to their remarkable ionic conductivity and decent mechanical properties. However, their application has been limited by imperfections such as moisture instability and poor electrochemical stability. Herein, a Sn and O is proposed dual‐substitution strategy in Li5.4PS4.4Cl1.6 (LPSC) to improve the moisture tolerance and boost the electrochemical performance. The optimized composition of Li5.5(P0.9Sn0.1)(S4.2O0.2)Cl1.6 (LPSC‐10) sintered at 500 °C exhibits a room‐temperature ionic conductivity of 8.7 mS cm−1, an electrochemical window up to 5 V, a critical current density of 1.2 mA cm−2, and stable lithium plating/striping. When exposed to humid air, LPSC‐10 exhibits a small increment in total resistance, generates a mild amount of H2S gas, and displays favorable structure stability after heat treatment. The first‐principles calculation confirms that the dual‐substituted composition less tends to be hydrolyzed than the un‐substituted one. The all‐solid‐state battery with LiIn|NMC811 electrodes presents a high initial discharge capacity of 103.6 mAh g−1 at 0.5 C rates and maintains 101.4 mAh g−1 at the 100th cycle, with a 97.9% capacity retention rate. The present study opens a new alternative for simultaneously promoting moisture and electrochemical stability.

Moisture‐Resistant Chiral Perovskites for White‐Light Circularly Polarized Photoluminescence

AbstractCircularly polarized luminescence (CPL) has recently caught increasing attention owing to its widespread applications from 3D display to quantum‐based optical computation. Among various CPL‐active materials, low‐dimensional hybrid perovskites have risen to prominence, benefiting from their excellent structural flexibility and optoelectronic properties. However, the exploration of hybrid perovskites with white‐CPL remains a challenge and most of them suffer from moisture instability. Here, a pair of moisture‐resistant 1D hybrid perovskites, (R‐C5H14N2)PbBr4·H2O (1R) and (S‐C5H14N2)PbBr4·H2O (2S), are reported in which [PbBr42−]∞ double chains are surrounded by chiral cations and water molecules forming the bulk assembled quantum‐helix structures. The strong quantum confinement in these unique structures facilitates exciton self‐trapping, which further synergizes the effect of chiral cations, endowing 1R and 2S with opposite broadband yellowish white‐CPL with a luminescence dissymmetry factor (glum) of 1.8 × 10−3 and a color rendering index up to 81. Notably, the dehydrated 1R can be recovered in humid air (60% relative humidity) within a few minutes via reabsorption of water molecules, exhibiting excellent moisture resistance, which is much better than most reported hybrid perovskites. A new path is paved here to further exploration of moisture‐resistant CPL‐active materials for multifunctional applications.

Self-healing 2D/3D perovskite for efficient and stable p-i-n perovskite solar cells

Beyond the p-i-n perovskite solar cell's high-power conversion efficiency (PCE), its moisture instability is the most challenging factor in its commercialization. Recently, the innovative use of three and two-dimensional multi-structures, by creating a barrier against the penetration of moisture and oxygen, has played a very influential role in improving the PSC's long-term stability. Here, a new strategy, the anti-solvent quenching method, is used to construct multi-structure perovskite by involving cetyltrimethylammonium bromide (CTAB) as an active agent. The solar cell efficiency is significantly improved during the perovskite formation on the substrate by creating a multidimensional (2D/3D) heterojunction perovskite. The synergistic role of using 2D/3D heterojunction perovskite structures led to the 29.2% improvement (14.58–18.84) in the PCE. The attractive ability of the 2D/3D active layer in self-healing has increased the perovskite's long-term stability under harsh environmental conditions.

Indium doped sulfide solid electrolyte with tamed lithium dendrite and improved ionic conductivity for all-solid-state battery applications

Sulfide solid state electrolytes capture much attention owing to their high conductivity and decent mechanical property. Nevertheless, the moisture instability and poor interfacial compatibility against lithium metal anode remain challenging and hinder the practical application. Herein, we report a novel indium (In) doping strategy based on the hard-soft-acid-base theory to tackle these issues. Optimized Li7P2.9S10.9In0.1 electrolyte exhibits a high ionic conductivity of 4.1 × 10−3 S cm−1 and achieves an enhanced interfacial compatibility. Importantly, as In partially replaces the phosphorus (P), the amount of released hydrogen sulfide can be significantly decreased and the air stability is improved. The all-solid-state battery assembled with the Li7P2.9S10.9In0.1 electrolyte demonstrates a high discharge capacity and a good cycling stability under a high current density of 1.0 C. This work provides a practical and effective method to design sulfide-based solid-state electrolyte with high ionic conductivity and enhanced air stability for all-solid-state battery applications.

Evaluation of the Humidification Effect of Street Trees Based on All-Inorganic Lead-Free K2CuBr3 Humidity Sensors

A suitable humidity environment is of great significance to the healthy and comfortable life of urban residents, and the humidification effect of street trees is crucial for effectively regulating microclimates in big cities. Therefore, evaluating the humidification capacity among species is a rewarding research aiming at providing bases for selecting appropriate street tree species. The leaves of trees generate water vapor through transpiration to slowly increase the environmental humidity, and humidity sensors with giant response, excellent linearity, and reliable repeatability are more conducive to analyzing and evaluating the subtle process in detail. Here, the antisolvent method was adopted to simplify the synthesis process of lead-free K2CuBr3, and the fabricated impedance-type humidity sensor based on K2CuBr3 microrods satisfied these requirements. The all-inorganic lead-free halide K2CuBr3 overcomes two drawbacks, including the toxicity of Pb and the moisture instability of most reported halide perovskites used in the field of humidity sensing. The impedance variation exceeds 106 Ω (162 Ω to 182 MΩ), with the relative humidity varying from 12 to 95%. In addition, the analysis of the corresponding complex impedance spectroscopy revealed the sensing mechanism. The intrinsic properties of K2CuBr3 are reflected at low humidity, and the proton transfer gradually dominates the sensing paths with increasing humidity. Furthermore, the K2CuBr3 humidity-sensitive layer is employed to evaluate the transpiration of street trees for the first time, and the successful evaluation of the humidification effect indicates more applications of lead-free halides.

Improving Structural and Moisture Stability of P2-Layered Cathode Materials for Sodium-Ion Batteries

P2-type Ni/Mn-based layered oxides are promising cathode materials for sodium-ion batteries (SIBs). However, ground challenges, e.g., irreversible phase transition during cycling, moisture instability, and inferior electrochemical performance, greatly impede their practical applications. Herein, a series of Cu-substituted P2–Na0.6Ni0.3–xMn0.7CuxO2 (0 ≤ x ≤ 0.2) cathode materials for SIBs are fabricated and the mechanisms responsible for their improved electrochemical performances are comprehensively investigated. It is discovered that Cu dopants with strong electronegativity could stabilize the crystal structure by inhibiting the common P2–O2 phase transition, leading to improved cycling stability. The expanded interlayer spacing after Cu doping is facilitated for the charge transfer kinetics, which ensures excellent rate performance. In addition, all Ni, Mn, Cu, and O participate in the charge compensation upon sodiation and desodiation through reversible redox reactions. More importantly, Cu substitution improves the moisture stability of the cathode materials because the Cu2+/Cu3+ redox couple increases the initial charging potential. This work provides a promising guidance for the design of low-cost, high-performance, and air-stable cathode materials with both cationic and anionic redox activities for SIBs.

Polyvinylpyrrolidone capped electrospun CH3NH3PbCl3 perovskite film as the electron transport layer in perovskite solar cell application

Due to the inherent moisture instability problem of hybrid lead halide perovskites, polymer additives have to turn out to be a significant research area to enhance the moisture stability of these materials. It has been found that polymer engineering on the absorber layer of solar cells significantly improves chemical stability and overall device performance. This work reports the fabrication of pristine and polyvinylpyrrolidone (PVP) polymer capped methylammonium lead chloride (CH3NH3PbCl3) perovskite film via the electrospinning method. A structural study using an X-ray diffractometer shows a sharp fall in average crystallite size from 66.05 nm to 39.69 nm when PVP is used in the synthesis procedure. A similar trend is also seen in the microscopic analysis, which depicts that the particle size has decreased for PVP added CH3NH3PbCl3 perovskite film in comparison to CH3NH3PbCl3 pristine film. The surface coverage and uniformity of the film is much more in the presence of PVP. It has been noted from energy dispersive X-ray analysis that the oxygen content is ∼16% more in the pure film, i.e. PVP hinders the effect of moisture in perovskite film, which is the prime objective of this work. Moreover, the optical properties have been analyzed using diffuse reflectance mode of UV–Vis-NIR spectroscope. Finally, the use of CH3NH3PbCl3 as the electron transport layer has been demonstrated in Glass/FTO/CH3NH3PbCl3/CH3NH3SnI3/Spiro-OMeTAD/Au structured perovskite solar cell using the SCAPS-1D simulator. The above-mentioned cell exhibits a power conversion efficiency (PCE) of 21.65%, fill factor (FF) of 72.21%, 32.44 mA/cm2 of short circuit current density (Jsc), and 0.924 V open-circuit voltage (Voc).

Thiamine additive engineering enables improved film formation towards high efficiency and moisture stability in perovskite solar cells

Perovskite solar cells (PSCs) attract widespread research interest due to their exceptional properties. However, the instability of the perovskite layer, especially the moisture instability, and existing defects seriously restrict the performance and limit the development of PSCs towards commercialization. Herein, we fabricate moisture-stable and efficient PSCs by incorporating a thiamine (THM) additive into a lead iodide (PbI2) precursor using a two-step spin-coating method. This strategy enables a better interaction between the THM additive and PbI2. Then, a higher energy barrier is produced when the material reacts with A-site cations to form perovskite crystals, resulting in larger grains and better-quality perovskite films. Through optimization of the concentration of the THM additive, the optimal perovskite achieves improved moisture stability and decreased trap states; thus, the corresponding unencapsulated devices achieve a remarkable power conversion efficiency (PCE) of 21.40% and maintain >92% of their initial PCE after 180 h in ambient air (∼50% humidity). The excellent performance is mainly attributed to the fact that THM promotes crystal growth and passivates defects in perovskite films.

Multifunctional liquid additive strategy for highly efficient and stable CsPbI2Br all-inorganic perovskite solar cells

CsPbI2Br all-inorganic perovskite has attracted considerable attention due to its high thermal stability and suitable bandgap, while the unsatisfactory crystallization quality and moisture instability significantly hinder its further application. Herein, a novel multifunctional liquid additive, 2-hydroxyethyl methacrylate (HEMA), is introduced into the CsPbI2Br precursor to ameliorate the above issues. Our results demonstrate that the functional groups of HEMA can interact with perovskite precursor, thus improving crystallization and passivating defects at the same time, and leading to a champion power conversion efficiency of up to 16.13%. Importantly, HEMA molecule in perovskite films will polymerize to a hydrophobic polymer at grain boundaries through breaking C = C bonds during the high temperature annealing process (160 °C). Moreover, this multifunctional liquid additive strategy endows perovskite films with promoted moisture tolerance by crosslinking perovskite grains and blocking moisture penetration, thus the unencapsulated device maintains 78% of its initial efficiency after aging at 30% relative humidity for 1000 h. These results demonstrate that the additive engineering with multifunctional molecule is applicable strategy for developing CsPbI2Br all-inorganic perovskite solar cells with both high efficiency and stability.

Double Free: A Promising Route toward Moisture-Stable Hypotoxic Hybrid Perovskites

Double Free: A Promising Route toward Moisture-Stable Hypotoxic Hybrid Perovskites

Molecular Insights into Water Vapor Adsorption and Interfacial Moisture Stability of Hybrid Perovskites for Robust Optoelectronics

• Grand canonical Monte Carlo predicts BET vapor adsorption isotherms on perovskites. • Vapor-induced degradation cannot be simply correlated with surface hydrophilicity. • Humidity affects ion dissociation rates rather than degradation energy barriers. • Coupled water adsorption and diffusion mechanism leads to perovskite ion solvation. • Material loss rates of 5.8 ~ 13.1 μm/s are estimated at 30 ~ 80% relative humidity. Understanding interfacial mass transfer processes, such as the water vapor adsorption-induced degradation of hybrid perovskites, is vital for improving the durability and performance of their optoelectronic devices in the ambient atmosphere with humidity. In this paper, vapor adsorption on prototypical MAPbI 3 , terminated by [MAI] 0 and [PbI 2 ] 0 surface, at different relative humidity (RH) levels is studied using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The resulting vapor adsorption isotherms match the Brunauer-Emmett-Teller (BET) adsorption model with heats of adsorption of 0.510 and 0.609 eV, respectively, for water monolayers on [MAI] 0 and [PbI 2 ] 0 . The formation of water monolayer on [MAI] 0 (for RH ≥ 30%) is consistent with its lower hydrophilicity compared to [PbI 2 ] 0 (for RH ≥ 10%), reflected from the larger water contact angle predicted. Based on predicted water surface coverages at various RHs, the moisture-induced surface degradation kinetics is studied using MD simulations and transition-state theory. Humidity has a minor impact on the degradation energy barriers due to the similar ion removal pathway by water solvation, but strongly affects the ion dissociation rates through the frequency of attempts to attack surface ions. [MAI] 0 is more vulnerable against water than [PbI 2 ] 0 , despite its lower hydrophilicity, implying that long-term exposed MAPbI 3 are mostly terminated by [PbI 2 ] 0 . Furtherly, averaged degradation material loss rates of 5.8 ~ 13.1 μm/s are estimated at 30 ~ 80% RH levels and 300 K, which is consistent with experiment observations. Finally, we offer a picture for the water-diffusion-based degradation mechanism and elucidate interesting hydrogen-bonding features at the vapor-MAPbI 3 interface. This research provides quantitative insights into the inherent vapor-perovskite interactions and addresses the moisture instability mechanisms in metal halide perovskites towards the rational design of water-resistant, long term stable and efficient optoelectronic devices.

Modification of Energy Level Alignment for Boosting Carbon‐Based CsPbI2Br Solar Cells with 14% Certified Efficiency

AbstractHole transfer material (HTM)‐free, carbon‐based all‐inorganic perovskite solar cells (C‐PSCs) are promising alternatives to conventional organic–inorganic hybrid PSCs in addressing thermal and moisture instability issues. However, the energy level mismatch between the inorganic perovskite and carbon electrode coupled, together with the incapability of the carbon electrode to reflect incident light for reabsorption, limits the power conversion efficiency (PCE) of C‐PSCs. To address these issues, herein, a new strategy of a hexyltrimethylammonium bromide (HTAB)‐modified CsPbI2Br perovskite surface is devised to reduce this energy offset from 0.70 to 0.32 eV and increase the built‐in potential by 70 mV for the final devices. Additionally, a CsPbI2Br perovskite film with a thickness of up to 800 nm is realized via a hot‐flow‐assisted spin coating approach in an ambient atmosphere with humidity of less than 80%. Reduced energy offset coupled with suppressed charge recombination and thick perovskite layer boosts the champion PCE of CsPbI2Br C‐PSCs to 14.3% (Jsc = 14.1 mA cm−2, Voc = 1.26 V, and fill factor = 0.806), and the average PCE to 13.9% under one sun illumination. A new certified efficiency record of 14.0% is obtained for HTM‐free inorganic C‐PSCs. Meanwhile, the moisture‐resistant barrier from the alkyl chain in HTAB improves the stability of the final devices.