Two-step Deposition Process Research Articles

Fabrication of High-Performance Neural Stimulation Electrode through Pulsed Electrochemical Deposition of IrOx onto Nano-Porous Platinum

Abstract Electrodes for neural stimulation are pivotal in medical and brain science applications. This study aims to prepare novel neural stimulating electrodes with enhanced electrochemical performance and improved mechanical stability through a two-step electrochemical deposition process. Initially, a highly porous platinum (Porous-Pt) electrode with high nanoscale roughness is fabricated, followed by the incorporation of IrOx onto the Porous-Pt surface. The resulting IrOx/Porous-Pt electrode combines the advantages of both materials, offering low impedance, significantly increased CIC, and improved mechanical stability. Scanning electron microscopy revealed that the porous surface of the electrode consisting of sphere-shaped Pt nanoparticles offers a significant effective surface area, promoting strong adhesion and stability for uniform IrOx deposition onto Porous-Pt. This characteristic contributed to the long-term mechanical stability of the IrOx/Porous-Pt electrode.

Air-Processed Efficient Perovskite Solar Cells With Full Lifecycle Management.

Despite the outstanding power conversion efficiency of perovskite solar cells (PSCs) realized over the years, the entire lifecycle from preparation and operation to discarding of PSCs still needs to be carefully considered when it faces the upcoming large-scale production and deployment. In this study, bio-derived chitin-based polymers are employed to realize the full lifecycle regulation of air-processed PSCs by forming multiple coordinated and hydrogen bonds to stabilize the lead iodide and organic salt precursor inks, accelerating the solid-liquid reaction and crystallization of two-step deposition process, then achieving the high crystalline and oriented perovskites with less notorious charge defects in the open air. The air-prepared PSCs exhibit a decent efficiency of 25.18% with high preparation reproducibility and improved operational stability toward the harsh environment and mechanical stress stimuli. The modified PSCs display negligible fatigue behavior with keeping 92% of its initial efficiency after operating for 32 diurnal cycles (ISOS-LC-1 protocol). Meanwhile, closed-loop lead management of end-of-life PSCs including suppression of lead leakage, toxicity evaluation of broken devices, and recycling of lead iodide components are comprehensively investigated. This work sheds light on a promising avenue to realize the entire lifecycle regulation of air-processed efficient and stable PSCs.

Fabrication of heterostructure multilayer devices through the optimization of Bi-metal sulfides for high-performance quantum dot-sensitized solar cells.

In this work, a titanium dioxide and lead sulfide (TiO2/PbS) nano-size heterostructure with tin sulfide was fabricated and coated via a two-step direct deposition process. Its microstructure, morphology, elemental composition, optical absorption, and photochemical activity were investigated. Linear sweep voltammetry and cyclic voltammetry curves substantiated its catalytic activity, indicating quantum dot effects of a well-developed space charge domain on the surface of the hybrid structure. These give rise to electron-hole recombination suppression and a high charge mobility rate. Moreover, direct stabilization was identified in current density, corresponding to the hybrid structures limiting the diffusion current process. Higher J SC values observed were substantiated by the role of quantum dot-size effects and enhanced crystalline structures, leading to a reduction in series resistance and an improved conversion efficiency of 10.05%. Overall, theoretical analyses and empirical findings indicated that the seamless migration of photoexcited electrons across the interfaces of SnS and PbS is linked to quantum dot effect synergy. This is facilitated by the space charge region, which serves as a conduit for efficient electron transfer between the respective materials.

Investigation of high-detectivity self-powered photodetectors of Rubrene/Bi2Se3 hybrid Van der Waals heterojunction

This paper investigates the Vander Waals heterostructure of organic rubrene and topological insulator Bi2Se3 with an atomically abrupt interface with exciting applications in electronic and optoelectronic devices. This organic/inorganic heterostructure (OIH) was prepared using a simple two-step physical vapor deposition process; based on this hybrid structure, a self-powered photodetector was then constructed. The Dirac surface state at the heterointerface enhances the splitting and transferring of photo-generated carriers, resulting in improved device characteristics. Under 1064 nm, the prepared photodetectors demonstrated a maximum responsivity (6.37 A/W), a high detectivity (3.42 × 1010 Jones), and ultrafast photoresponse speeds with rise time (1.17 µs) and decay time (1.59 µs), respectively. These promising results suggest that these PDs can be used in various photodetection applications and may lead to developing new devices.

High-Performance WS2 MOSFETs with Bilayer WS2 Contacts.

WS2 is a promising transition-metal dichalcogenide (TMDC) for use as a channel material in extreme-scaled metal-oxide-semiconductor field-effect transistors (MOSFETs) due to its monolayer thickness, high carrier mobility, and its potential for symmetric n-type and p-type MOSFET performance. However, the formation of stable, low-barrier-height contacts to monolayer TMDCs continues to be a challenge. This study introduces an innovative approach to realize high-performance WS2 MOSFETs by utilizing bilayer WS2 (2L-WS2) in the contact region grown through a two-step chemical vapor deposition process. The 2L-WS2 devices demonstrate a high I ON/I OFF ratio of 108 and a saturated drain current, I D(SAT), of 280 μA/μm (386 μA/μm) at room temperature (78 K), even while still using conventional metal (Pd or Ni) contacts. Devices featuring a 1L-WS2 channel and 2L-WS2 in the contact regions were also fabricated, and they exhibited performance comparable to that of 2L-WS2 devices. The devices also exhibit good stability with nearly identical performance after storage over a 13 month period. The study highlights the benefits of a hybrid channel thickness approach for TMDC transistors.

Multifunctional anion-cation modulation engineering for Sn-Pb perovskite solar cells

The binary tin and lead (Sn-Pb) perovskites are a significant cornerstone for all-perovskite tandem devices due to their high efficiency, low toxicity, and narrow bandgap properties. However, the fast crystallization of the perovskite film and the facile conversion of Sn2+ to Sn4+ during the preparation process are major obstacles to achieving remarkable Sn-Pb perovskite solar cells (PSCs). Herein, we develop a multifunctional anion-cation modulation strategy to synthesize high-quality FAPb0.5Sn0.5I3 (Eg∼1.24 eV) perovskite films by mixing methylamine acetate (MAAc) ionic liquid with the PbI2 and SnI2 solutions through a two-step sequential deposition process. MA cations tend to insert the tin/lead-halogen octahedral framework and occupy the A-site in the first-step. Subsequently, the volatile MA cations can produce ion exchange reactions with FA+ from the formamidinium iodide in the second step, leading to high quality crystallization process. Additionally, the Ac anions can efficiently suppress Sn2+ oxidation with balancing the crystallization rate of the Pb/Sn components, and passivate the defect sites located on the grain boundary and surface, owing to the strong coordination of Ac- with Sn2+ and Pb2+. As a result, the optimized PSC reaches a power-conversion efficiency of 21.22 %, which is the highest value reported for FAPb0.5Sn0.5I3 based solar cells with a two-step method, compared to the control device with 12.86 %. Moreover, the perovskite devices show prominent reproducibility and stability performance, maintaining >80 % of the initial efficiency after being stored in the N2-filled glovebox for 1000 h.

Direct Selective Epitaxy of 2D Sb2Te3 onto Monolayer WS2 for Vertical p-n Heterojunction Photodetectors.

Two-dimensional transition metal dichalcogenides (2D-TMDs) possess appropriate bandgaps and interact via van der Waals (vdW) forces between layers, effectively overcoming lattice compatibility challenges inherent in traditional heterojunctions. This property facilitates the creation of heterojunctions with customizable bandgap alignments. However, the prevailing method for creating heterojunctions with 2D-TMDs relies on the low-efficiency technique of mechanical exfoliation. Sb2Te3, recognized as a notable p-type semiconductor, emerges as a versatile component for constructing diverse vertical p-n heterostructures with 2D-TMDs. This study presents the successful large-scale deposition of 2D Sb2Te3 onto inert mica substrates, providing valuable insights into the integration of Sb2Te3 with 2D-TMDs to form heterostructures. Building upon this initial advancement, a precise epitaxial growth method for Sb2Te3 on pre-existing WS2 surfaces on SiO2/Si substrates is achieved through a two-step chemical vapor deposition process, resulting in the formation of Sb2Te3/WS2 heterojunctions. Finally, the development of 2D Sb2Te3/WS2 optoelectronic devices is accomplished, showing rapid response times, with a rise/decay time of 305 μs/503 μs, respectively.

Interfacial competing interaction eliminates voids in the buried interface for efficient and stable perovskite solar modules on bare NiOX

Perovskite solar cells (PSCs) with impressive efficiency is promising for commercialization. However, when scaling up PSCs to large-area perovskite solar modules (PSMs), the rapid degradation of performance and stability still remains a grand challenge. One of the main causes of the degradation is the presence of local voids in the buried interface for large-area films, which we find could be attributed to the unbalanced interfacial interaction between precursor solvent and substrate. Here we improve a scalable and low-temperature sequential two-step chemical bath deposition process aiming for high quality NiOX. Further with the modulation of A-site cations to enhance the interaction between DMSO and perovskite precursor, the potential for DMSO absorbing on the NiOX could be eliminated. This strategy can inhibit the delay movement of DMSO on NiOX and improve the buried interfacial quality, with compact morphology and absent of voids. The inverted structured PSCs and PSMs based on the bare NiOX and modified perovskite precursor reach a champion efficiency of 22.40% and 19.09%, respectively, which are both among the highest reported values. The highly efficient PSMs also exhibit a long-term operational stability, which retain 84% of the initial performance after 1056 h operating under one-sun illumination.

Scalable Large-Area 2D-MoS2/Silicon-Nanowire Heterostructures for Enhancing Energy Storage Applications.

Two-dimensional (2D) transition-metal dichalcogenides have shown great potential for energy storage applications owing to their interlayer spacing, large surface area-to-volume ratio, superior electrical properties, and chemical compatibility. Further, increasing the surface area of such materials can lead to enhanced electrical, chemical, and optical response for energy storage and generation applications. Vertical silicon nanowires (SiNWs), also known as black-Si, are an ideal substrate for 2D material growth to produce high surface-area heterostructures, owing to their ultrahigh aspect ratio. Achieving this using an industrially scalable method paves the way for next-generation energy storage devices, enabling them to enter commercialization. This work demonstrates large surface area, commercially scalable, hybrid MoS2/SiNW heterostructures, as confirmed by Raman spectroscopy, with high tunability of the MoS2 layers down to the monolayer scale and conformal MoS2 growth, parallel to the silicon nanowires, as verified by transmission electron microscopy (TEM). This has been achieved using a two-step atomic layer deposition (ALD) process, allowing MoS2 to be grown directly onto the silicon nanowires without any damage to the substrate. The ALD cycle number accurately defines the layer number from monolayer to bulk. Introducing an ALD alumina (Al2O3) interface at the MoS2/SiNW boundary results in enhanced MoS2 quality and uniformity, demonstrated by an order of magnitude reduction in the B/A exciton photoluminescence (PL) intensity ratio to 0.3 and a reduction of the corresponding layer number. This high-quality layered growth on alumina can be utilized in applications such as for interfacial layers in high-capacity batteries or for photocathodes for water splitting. The alumina-free 100 ALD cycle heterostructures demonstrated no diminishing quality effects, lending themselves well to applications that require direct electrical contact with silicon and benefit from more layers, such as electrodes for high-capacity ion batteries.

Polymer additive-promoted porous PbBr2 layer for fabricating high-performance carbon-based CsPbIBr2 perovskite solar cells through a two-step sequential deposition process

A PEG-assisted two-step sequential deposition process considerably enhances the CsPbIBr2 perovskite quality and promotes the photovoltaic performance of CsPbIBr2 PSCs.

Effect of copper doping on the photocatalytic performance of Ni2O3@PC membrane composites in norfloxacin degradation.

In this study, copper (Cu) and nickel oxide (Ni2O3) microtubes (MTs) were synthesized using an electroless template deposition technique within porous polycarbonate (PC) track-etched membranes (TeMs) to obtain Cu@PC and Ni2O3@PC composite membranes, respectively. The pristine PC TeMs featured nanochannels with a pore density of 4 × 107 pores per cm2 and an average pore diameter of 400 ± 13 nm. The synthesis of a mixed composite, combining Cu and Ni2O3 within the PC matrix, was achieved through a two-step deposition process using a Ni2O3@PC template. An analysis of the resultant composite structure (Cu/Ni2O3@PC) confirmed the existence of CuNi (97.3%) and CuO (2.7%) crystalline phases. The synthesized catalysts were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) analysis, and atomic force microscopy (AFM). In photodegradation assessments, the Cu/Ni2O3@PC mixed composite demonstrated higher photocatalytic activity, achieving a substantial 59% degradation of norfloxacin (NOR) under UV light irradiation. This performance surpassed that of both Ni2O3@PC and Cu@PC composites. The optimal pH for maximum NOR removal from the aqueous solution was determined to be pH 5, with a reaction time of 180 min. The degradation of NOR in the presence of these composites adhered to the Langmuir-Hinshelwood mechanism and a pseudo-first order kinetic model. The reusability of the catalysts was also investigated for 10 consecutive runs, without any activation or regeneration treatments. The Cu@PC membrane catalyst demonstrated a marked decline in degradation efficiency after the 2nd test cycle, ultimately catalyzing only 10% of NOR after the 10th cycle. In contrast, the Ni2O3@PC based catalyst demonstrated a more stable NOR degradation efficiency throughout all 10 runs, with 27% NOR removal observed during the final test. Remarkably, the catalytic performance of the Cu/Ni2O3@PC mixed composite remained highly active even after being recycled 4 times. The degradation efficiency exhibited a gradual reduction, with a 17% decrease after the 6th run and a cumulative 35% removal of NOR achieved by the 10th cycle. Overall, the findings indicate that Cu/Ni2O3@PC mixed composite membranes may represent an advancement in the quest to mitigate the adverse effects of antibiotic pollution in aquatic environments and hold significant promise for sustainable water treatment practices.

Thermal evaporated PbI2 enables high-quality perovskite films and improves their solar cell performance

The quality of the light-absorbing perovskite layer is essential for fabricating highly efficient and stable perovskite solar cells (PSCs). The utilization of vacuum-deposited PbI2, instead of spin-coated PbI2, significantly enhanced the quality of the perovskite film in a two-step deposition process. A uniform and agglomeration-free formation of the PbI2 layer achieved through the vacuum-deposition method promoted the efficient intercalation of MAI and led to the formation of a high-quality MAPbI3 perovskite layer with enhanced optical properties and surface morphology. Through electrochemical impedance spectroscopy, we discovered that PSCs with vacuum-deposited PbI2 demonstrate suppressed ion migration compared to devices with spin-coated PbI2. With the application of vacuum-deposited PbI2, the power conversion efficiency (PCE) of the device is superior to devices using spin-coated PbI2. Moreover, after a 40 h thermal stability test, the device with vacuum-deposited PbI2 maintained a PCE of over 50% of its initial efficiency, while the PSC with spin-coated PbI2 dropped to 10%.

Simultaneous Incorporation of CsI in the Two-step Deposition Process Boosts the Power Conversion Efficiency and Stability of Perovskite Solar Cells.

Two-step deposition method has been widely exploited to fabricate FA1-x Csx PbI3 perovskite solar cells. However, in previous studies, CsI is mainly added into the PbI2 precursor with DMF/DMSO as solvent. Here in this study, a novel method to fabricate FA1-x Csx PbI3 perovskite has been proposed. The CsI is simultaneously added into the PbI2 precursor and the organic FAI/MACl salts solution in our modified two-step deposition process. The resulting FA1-x Csx PbI3 film exhibits larger perovskite crystals and suppressed defect density (4.05×1015 cm-3 ) compared with the reference perovskite film (9.23×1015 cm-3 ) without CsI. Therefore, the obtained FA1-x Csx PbI3 perovskite solar cells have demonstrated superior power conversion efficiencies (PCE=21.96 %) together with better long-term device stability.

Self-passivated CdS buffer layer for antimony sulfide solar cells

Sb2S3 has been paid extensive attentions as absorber for solar cells. Comparing with some oxides, CdS exhibits excellent compatibility to Sb2S3 therefore is most commonly used as buffer layer (BL) materials for Sb2S3 solar cells. Proper passivation can enhance the performance of CdS buffer layer thus raising the performances of Sb2S3 solar cells. Herein, we put forward a self-passivation strategy to enhance the performance of CdS by a two-step deposition process to fabricate the self-passivated CdS BL. First, we adopted spin coating combined with annealing process to prepare flaked CdS on FTO, then we performed passivation process to the CdS by depositing another layer of CdS with chemical bath deposition (CBD) method. After Sb2S3 was deposited on the self-passivated CdS by hydrothermal method, a solar cell with FTO/CdS (∼90 nm)/Sb2S3 (160 nm)/Spiro-OMeTAD(48 nm)/Ag(32 nm)structure was obtained by deposition of hole transport layer and Ag electrodes. Comparing with the single spin-coating processed CdS BL or single chemical bath deposited CdS BL, the self-passivated CdS presents better performance. The CBD process presents distinctive passivation effects to the first layer. In consequence, we obtained the highest PCE of 6.04 % in the Sb2S3 solar cells on the self-passivated CdS BL. The present work supplies a unique route to enhance the performances of CdS buffer layer.

Long-lifespan sodium ion capacitors enabled by in-situ electrochemically induced graphitization and rearrangement of carbon layers in Fe2O3@C modified vertical-aligned carbon nanotubes

Developing high-capacity anodes with fast kinetics and stable structure is critical for the effective implementation of sodium ion capacitors (SICs). In this study, Fe2O3@C nanoparticles modified vertically aligned carbon nanotubes (VACNTs) composites are designed and employed as SIC anodes through a two-step chemical vapor deposition (CVD) process with the aid of a refined Fe3O4/AlOx dispersion catalyst. With nano-sized Fe2O3 coated with defected carbon layers sufficiently loading onto the VACNTs substrates, the resulting composites demonstrate remarkable sodium storage properties, with a high areal specific capacity (1.26 mAh cm−2 at 0.2 mA cm−2) and rate performance (0.19 mAh cm−2 at 5.0 mA cm−2). Moreover, continuous capacity promotion is observed over 1000 cycles, leading to superior cycling performance (0.444 mAh cm−2 at 1 mA cm−2), with 178% retention after 1000 cycles. This improved cycling performance is attributed to the defective structure and high specific surface area of the VACNTs, which accommodates the volume change of the Fe2O3 particles. In addition, the induced locally graphitization and rearrangement of the carbon layers are demonstrated, which results in better kinetics for Na+ transfer, further enhancing capacity retention over long cycles.

Manganese-substituted kesterite thin-films for earth-abundant photovoltaic applications

Thin film photovoltaic devices based on CdTe and Cu(In,Ga)Se2 find in Cu2ZnSn(S,Se)4-based technology a more eco-friendly alternative. To further reduce production costs and improve sustainability, other abundant metals, such as manganese, can be tested as a potential alternative to zinc. Mn is a safe and Earth-abundant element, and it can be used in light absorber materials when it is part of quaternary chalcogenides with copper and tin. This work reports on the growth and characterization of Cu2MnSnS4 thin films produced by a two-step deposition process. The metallic precursors have been deposited by sputtering and the stack annealed at high temperatures in sulphur atmosphere. The layers, obtained in Cu-poor Mn-poor compositional regime, have been tested in solar devices with a record efficiency of 1.13% and a high open-circuit voltage of about 445 mV delivered by the champion device after over one year from the first PV measurement. X-ray diffraction and X-ray photoelectron, Raman, photoluminescence, and admittance spectroscopies have been used to investigate the Cu2MnSnS4 defectivity, and a scenario of high defects has emerged. Therefore, to promote the development of Mn-based photovoltaics the synthesis methodology should be optimized and the device architecture should be specifically designed for the compound.

Multifunctional Metal-organic Frameworks Capsules Modulate Reactivity of Lead Iodide toward Efficient Perovskite Solar Cells with Ultraviolet Resistance.

The two-step sequential deposition process is demonstrated as a reliable technology for the fabrication of efficient perovskite solar cells (PVSCs). However, the complete conversion of dense PbI2 to perovskite in planar PVSCs is tough without mesoporous titanium dioxide as support. Herein, multifunctional capsules consisting of zeolitic imidazolate framework-8 (ZIF-8) encapsulant and formamidinium iodide (FAI) are introduced between tin oxide (SnO2 ) and lead iodide (PbI2 ) layer. Intriguingly, the capsule dopant interlayer benefits the formation of porous PbI2 film due to the porous nanostructure of ZIF-8 which is favorable for the subsequent intercalation reaction. Furthermore, the constituent of the perovskite precursor in ZIF-8 pores can convert into the crystal nuclei of perovskite by reacting with PbI2 first, thereby promoting further perovskite crystallization. Significantly, the incorporation of ZIF-8 can enhance the resistance of perovskite against ultraviolet (UV) illumination due to down-conversion effect. Consequently, the modified device achieves a champion power conversion efficiency (PCE) of 24.08% and displays enhanced UV stability, which can sustain 83% of its original PCE under 365nm UV illumination for 300h. Moreover, the unencapsulated device maintains 90% of initial PCE after 1500h storage in dark ambient conditions with a relative humidity range of 50∼70%. This article is protected by copyright. All rights reserved.

Simple cathodic deposition of FeS/NiS-activated Ni/NiO heterojunctions for high-concentration overall water splitting reactions

To produce hydrogen through electrolysis of water, the creation of effective and affordable electrodes for overall water splitting is essential. We present the deposition of active oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) components on the same NF in this work, enabling the synergistic effect of FeS/NiS and Ni/NiO active components for effective overall water splitting. In alkaline electrolytes, NiFe@NF electrodes deposited using a straightforward two-step cathodic deposition process at various currents exhibit good catalytic activity for both OERs and HERs. For the electrode to be stable over time, Ni/NiO is firmly bonded to NF, and the specific surface areas of the FeS/NiS nanoflowers provide efficient electron transport. The electrode outperformed the RuO2 electrode by achieving a current density of 10 mA cm−2 at an OER overpotential of 168 mV. Additionally, the HER only needs a 84 mV overpotential to reach a current density of 10 mA cm−2. In addition, an electrolytic cell constructed with the same NiFe@NF as the cathode and anode requires a cell voltage of only 1.47 V to achieve a current density of 10 mA cm−2. It can operate stably for a long time (120 h) at high temperature and high concentration conditions. This work highlights the importance of active components with simultaneous OER and HER activities on electrodes for efficient catalytic applications in overall water splitting.

Fabrication of Bismuth–Antimony–Telluride Alloy/Poly(3,4-ethylenedioxythiophene) Hybrid Films for Thermoelectric Applications at Room Temperature by a Simple Electrochemical Process

In this study, we synthesized flexible bismuth–antimony–telluride (Bi0.5Sb1.5Te3 (BST))/poly(3,4-ethylenedioxythiophene) (PEDOT) composite films using a simple two-step electrochemical deposition process. After electrochemically polymerizing ethylenedioxythiophene (EDOT) first on the gold-coated polyethylene terephthalate (PET), BST was deposited using the PEDOT layer as a working electrode. The effect of electrochemical potential on the morphology and crystal structure of the electrochemically deposited BST alloy was investigated through scanning electron microscopy and X-ray diffraction. The results show that a cauliflower-like morphology appears with a preferential orientation along the (110) direction of Bi0.5Sb1.5Te3 within the proper potential range. We also optimized the deposition time to achieve higher thermoelectric performance on the BST/PEDOT composite film. The optimal BST/PEDOT film produced by electrochemical deposition of BST for 80 min showed superior performance compared to other previously reported organic/inorganic composite materials. The maximum power factor was about 427 μW m–1 K–2 at an electrical conductivity of 167 S cm–1 and a Seebeck coefficient of 160 μV K–1. This process can be readily applied to practical fabrication of efficient thermoelectric materials.

Synergistic Effect of Ammonium Salts in Sequential Deposition toward Efficient Wide-Band-Gap Perovskite Photovoltaics with PCE Exceeding 20%

The controlled crystallization process is of significance to the morphological quality of wide-band-gap perovskite absorbers, especially with excessive bromide ions. Moreover, the non-radiative recombination assisted by surface defects is one of the major unfavorable factors that confines the development of highly efficient wide-band-gap perovskite solar cells (PSCs). Here, 1.65 eV wide-band-gap PSCs are constructed by a sequential deposition method with tailored morphology of highly reproducible perovskite absorbers. The controlled crystallization with the help of NH4Cl enables the perovskite films with larger and more uniform grains, which result in less bulk defects. At the same time, (NH4)2SO4 as a passivation layer reduces the uncoordinated Pb2+ and Pb0 defects on the surface of the perovskite film and improves the hydrophobicity due to newly formed insoluble PbSO4. Eventually, the synergistic effect of ammonium salts results in a high VOC of 1.18 V and an optimal efficiency of 20.43%, which is one of the highest power conversion efficiencies for 1.65 eV wide-band-gap-based PSCs constructed by a two-step deposition process. This work confirms that the sequential deposition method and addition of proper ammonium salts are effective strategies toward highly efficient and stable wide-band-gap PSCs.